Denford Lathe Retrofit

[outback]

I'm in the process of retrofiting a Denford CNC lathe. I'll post my progress at it goes but first I have a quiestion.

I just built a nice 18" X 38" X 32" high stand for the lathe project. It is made of 2" square 80-20 extruded aluminum. My question is a 18 X 38 top for the stand. Should the lathe be mounted to a steel plate or could I use a sheet of 3/4" plywood or maybe two layers of plywood. If the top needs to be steel what should I use, 3/8, 1/2.....? The lathe bed and head weigh in at about 120LB,

Thanks,
Jim

[DICKEYBIRD]

Hi Jim, I'm really looking forward to seeing how you do your retro! I think a heavy gauge (13 or 14 ga?) sheet metal top with a couple braces under the lathe mounting points would work well for a top. Depends on what you have lying around. I'm sure there are some who will say nothing less than 1" plate will work.;)

For my Denford's new home, I modified an existing 36"L X 30"W X 36"H 2x4 wood frame I had under an old homemade CNC router . I covered the top with 1x6 tongue & groove pine with the grain going across the short dimension and added some diagonal braces to stiffen it up. The T&G locked in very nice and seems to be very sturdy.

I picked up a piece of black plastic carpet runner at Lowe's and covered the top with the grooves facing down to give a smooth surface for wiping up oil spills.

I'm using the original ORAC base to mount the lathe on and house the electrical stuff. The panel across the back provides a backsplash as well. It's real stout and has 2 rails running longways on the bottom that spreads the load across the wood table top. It looks and feels plenty sturdy.

The lathe will be pretty high off the ground but I did a few dry runs and it feels pretty good actually. I have to be careful with my back and I'll try it for a while as-is when I get it running. I can always shorten it if necessary.

[outback]

As of 11:30PM Sunday this is what I have done. Got a stand built for the lathe made from 80-20 aluminum. The base I bought from a friend that is heavy duty with wheels.

Below I'm making stepper motor mounts on a home built mill. I use this small mill more than I use my CNC Bridgeport. The sloted hole are to adjust the timming belt.
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Steppermotormtg.jpg

Here is the stand and the Stepper motors mounted.
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/CNClathebeginning.jpg

Bed time,
Jim

[DICKEYBIRD]

Wow, you're moving right along there Jim. Those are some manly lookin' stepper motors you got there!

I'm curious to see what you're using for a spindle motor and how you mount it.

I'm still mired up with pesky paying jobs and haven't been able to do anything other than order parts and daydream.:rolleyes:

ps: Got the contactors, thank you so much!:D

[DICKEYBIRD]

Oh yeah, did you find a source for the 10 groove Poly V/Micro V belts & sheaves to match the spindle?

I thought I'd got lucky Friday. I scrounged around work & found a Land Rover Disco alternator pulley & it looked perfect until I got it home & found out the groove spacing was wider than the J series Poly V @ 3/32".:(

What's the max spindle speed you're shooting for?

[outback]

Have a problem with the carriage stepper mtg. Does anyone have a pic or description of the original stepper mtg. I see the tapped holes in the lathe match the mtg holes on the stepper but how did they adjust the timing belt. I'm reluctant to slot the holes on the stepper motor. Did they have an idler pulley to tension the timing belt? What I'm doing now has several clearance issures. I have an idea brewing in my head how to resolve this issue but I don't wish to reinvent the wheel if there is no need to.
stepper mtg (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Stepperspindlemotors.jpg)

The cross slide stepper mounted ok with my adjustment system. Still curious as the original techneque.
cross slide mtg (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Crossslidesteppermtg.jpg)

The spindle motor is orginal Denford.

Jim

[DICKEYBIRD]

The picture in the manual shows the mount plate attached to the stepper motor with the spacer tubes between it and the lathe body.

Maybe the bolts are smaller than the tube ID and the bolt holes in the stepper motor allowing a bit of wiggle room??

My NEMA 23 steppers are smaller than the 34 bolt pattern so I think I can mill slots in the mount plate allowing a bit of adjustment.

Hope this pic helps:

http://i57.photobucket.com/albums/g227/DBAviation/ORACStepMt.jpg

[outback]

What you show is kinda what I figured. They must use with wiggle room in the screws for tensioning. WOW. Well, at least I have a 100XL037 belt on order. I'll have the belt tomorrow.

The clearance holes in the stepper are for a #10 screw. I suppose I could use a #8 or #6 screw for more wiggle room. This could be easier than I thought.

Thanks for the diagram.
Jim

[DICKEYBIRD]

There probably wouldn't be much need for adjustment as those little belts are pretty darn stout and don't stretch.

I guess they built 'em to such close tolerances over there in northern England that the belts fit perfect from the get-go. Adjustment devices cost money and it's a well known fact that Yorkshiremen are pretty tight with a tuppence ha'penny.:D

[outback]

I had this idea on a timing belt tensioning adjustment so I had to go build it. If nothing else it will be easier to service the belt and stepper motor. It makes things kinda fall into place. Clearance issues resolved now.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Stepperspindlemotors2.jpg

Adjustable threads (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Adjustablethreads.jpg)

Stepper Mtg (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Carriagestepper.jpg)

I'm rather impressed the Brits would build precise enough tension adjustments would not be required. It does make sense.

I'm ready to start wiring the control now. The VFD will be here tomorrow. This could proceed rather quickly now.

Milton, I would check with Motion Industries for that 10 groove pulley. I ended up buying the spindle motor from the guy in
Ann Arbor and the pulley was already on it. Glad I did now. Made life easier.
Jim

[DICKEYBIRD]

That's a great solution Jim...looks real sturdy and easy to adjust.

Thanks for the Motion Ind. tip, looks like they have a sheave.:)

[outback]

I got the spindle running with the variable frequency drive I bought on Ebay. Decided at the last minute to add a motor contactor with overloads for the variable frequency drive. A little added safey and insurance. later I will add buttons to to STOP and REVERSE the spindle. Sweet running machine. Very quiet.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/VFD.jpg

VFD close up (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/VFDcloseup.jpg)

Click for large pic (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/VFDLarge.jpg)

contactor and overload. Outlets for computer and cnc control (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/overloadsContactor.jpg)

Next the controller build then it should be play time
Jim

[DICKEYBIRD]

Yer killin' me Jim; it's lookin' GOOD! I wish I was that far along. Are you going to put on a spindle speed sensor & disc? Does your control have the ability to control the VFD/motor speed?

Between work and pesky side jobs I got nothing done on mine other than getting a few more parts in. Your Motion Ind. tip really paid off. I just received a 10 groove J series 2.8" sheave and the matching 5/8" taper lock hub to fit my motor. That should give me close to 2000 rpm top speed if needed and I hope enough grunt at lower speeds. Dry runs with the Baldor DC motor & KB speed control sure feel powerful. We'll see later.

Keep the pics a-comin'...I need the motivation!:)

[John Stevenson]

Yer killin' me Jim; it's lookin' GOOD!

Keep the pics a-comin'...I need the motivation!:)

Too much motivation :(

Mine is well down the list of machines to do but just been down to Leicester today where the machine is stored and stared longingly at it sat 15 foot up in the air on racking.

Mine is complete but the controller is dead. Just realised today its the model fitted with an air chuck.

Where Jim's has the menu ? plate below the word ORAC on the headstock, mine has two push buttons marked open and close.

Only problem with this is you can't use long lengths because of the chuck mechanism so it's only a chucker but it does have a 3 jaw sat on the base plate.

[DICKEYBIRD]

John you need to root around in those dusty ol' shops you wander in & out of and find you, me & Jim a nice Denford toolchanger each to play with.

That's not much to ask for and I can wait 'til Christmas.:D

[John Stevenson]

Milton,
PM sent.

[outback]

I'm using a breakout board made by Bob Cambell designs. I think it will do speed control but I'm not going be concerned about spindle speed control by the controller for a while. I mounted the VFD in a convenient place so I can control the spindle RPMs myself.

The VFD has a speed control knob in the front. I'm going to add push buttons for forward and reverse near the VFD. However, I will start and stop the spindle from the control.

I'll start wiring the control this weekend. See how it goes.

I dawned on me why the Denford lathe is so smooth and quiet. The lathe
has no gears. Feeds, speeds and spindle is all controlled electricaly.
Jim

[John Stevenson]

I have never taken any pictures of my ORAC as it's never been here, bought then farmed out for storage. Came from a college in Oxford.

Was looking thru some folder last night for a drawing and found this.

http://www.stevenson-engineers.co.uk/files/ORAC1.jpg

Not a brilliant picture as it came off the auction site and has been blown up. I saved it and printed it out for when I went to collect it.

The guard is interesting in that it slides on a rear rail and you can put it where you want but you need the original base and back for it to work correctly.

[DICKEYBIRD]

That tinted plastic guard is pretty cool. I got the base/splash panel with mine but it didn't come with the guard. I'll probably make one later on if I can get a deal on some Lexan. It did come with a state of the art audio cassette player and stereo speakers though.:)

The base is a sturdy, well-built structure built out of heavy sheet metal. I removed the speakers and left the grilles for cooling air inlets. While removing them and the misc. brackets & electrical fittings, I was impressed with the high quality hardware & workmanship. Every socket head screw & nut was high grade and had its proper flat washer & star lock washer in place. Not a one missing in the pile of stuff I removed. Those Yorkies do good work.:D

I did notice a little weak spot (IMHO) in the design of the base though. The 2 spots where the lathe bolts to the base had the paint fretted off indicating some relative movement between the two. The top is heavy gauge but is unsupported between the hinged back panel and the front allowing it to flex. I've never seen or heard a "stock" one run but I'd bet it tends to resonate & jingle at certain speeds.

I'm going to bolt in a couple angle iron braces under the top, across the short direction near the mount pads with flat bar braces connected to a couple more angle iron braces across the floor. I may use a big chunk of the freebie 1/2" alum. plate I lucked into and bolt it to the floor as a heatsink to mount all of the electrical stuff onto. My Denford MicroMill is done that way and it works well. I'm fairly obsessive when it comes to keeping electrical widgets as cool as possible.

ps: I'll say it for you John: "Get yer bloody finger out and int' shop. Finish yer bleedin' girlie-man side work and get on with some real work!"

[Euph0ny]

With that shield, it does look like Orac!

Cool!! BBC - BBB7*




*BBC - Bring Back Blake's 7 :-)

[outback]

Progress on the CNC control for my lathe project. Not quite done but had a productive day. Control is not quite done. Need to connect the 40VDC power supply and the stepper motors. Left a space for a fourth axis driver board. Upper left is a 24VDC power supply used to operate the Master Control relay, push buttons and anything else that come up. The breakout board is from
Bob Cambell designs. This is my first project using the Bob Cambell breakout board. In the past I used a breakout boards called
"Axxuss". They are no longer available.
Old Axxuss Breakout board (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/axxus.jpg)

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/lathecontrol.jpg

I plan to mount the toroidal transformer to the inside door of the cabinet. The cabinet was an Ebay purchase. Already had some
holes punched and few push buttons.
Control cabinet (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/lathecontrolcabinet.jpg)

Does not look like I will have spindle speed control. The breakout board has connecting pins for speed control but I'm unable to locate the gadget that does the job.
Jim

[John Stevenson]

Spindle speed not fitted on that board.

[DICKEYBIRD]

Looks very neat & tidy Jim. Won't be long now!

Is that 3 Geckos I'm seeing? If so, what's #3 for?

[John Stevenson]

Toolchanger ?

[outback]

Looks very neat & tidy Jim. Won't be long now!

Is that 3 Geckos I'm seeing? If so, what's #3 for?


A number of possibilities for the 3rd or even the 4th Gecko drive. I could
make the tailstock CNC controlled, Tool Changer. Number one is a stepper
motor to run the spindle with a timing belt for threading.

CNC threading was a primary motivation for the CNC Lathe project. I figure I'll be able to cut SAE threads, Metric threads, multiple lead threads and extra special threads. A year ago I cut a tripple lead thread on my
13 X 40 JET lathe. I have also turned away jobs that required a thread my JET lathe was not geared for and taps were also hard fine.

I did find a spindle control but I think it will be more trouble than it is worth. I plan on turning small stuff with carbide and figure the spindle speeds will be mostly at full speed and changed buy turning a dial on the VFD.

http://www.texasmicrocircuits.com/THCImages/Spindle_control.jpg

I'm already using this guys pendent on my CNC mill and it is a great little device. It has a joy stick for rapids and jogging.
Basicly run the entire machine right from the pendent.
http://www.texasmicrocircuits.com/bc.htm

I'll be working on this project for most of the day so stay tuned. I have employees (family members) working in the shop today so there is no room for me and them both. So I'll work on the CNC lathe project.
Jim

[DICKEYBIRD]

I have employees (family members) working in the shop today so there is no room for me and them both. So I'll work on the CNC lathe project.So that's how I get more time to work on fun stuff! :D

[outback]

So that's how I get more time to work on fun stuff! :D

Oh ya,,,,employees are great. They are in the shop repairing products imported from China by a customer of mine.

The down side is I need to pay the employees (family members) at the end of
each day. Times are tough in these parts.

"Even tougher when your stupid" Quote made by: John Wayne

Jim

[DICKEYBIRD]

Your stepper/spindle/threading comments got me to Googling like crazy but I'm not coming up with much info I can understand. I'm hoping you get it working without EMC or other complex finagling.

[outback]

Your stepper/spindle/threading comments got me to Googling like crazy but I'm not coming up with much info I can understand. I'm hoping you get it working without EMC or other complex finagling.

Milton;

The guy in Michigan that sold me the lathe showed me his lathe with a rather small stepper mounted to the lathe head. All he needed to do was slip one of those XL037 timing belts on the stepper motor and spindle. Needless to say the 1/2hp spindle motor is not running during threading.

I figure the stepper running the spindle will be given angular commands and the carriage stepper linear commands. Sooo.. for every 360 degrees the spindle turns the carriage should move right to left = to the pitch (lead) of the thread. For 10 turns of the spindle there will be so much advance on the carriage for a continuous thread, or the pitch X 10.

I hope I have it right because I have never done it before. It will be great if
it works. Just think, the threads will start and stop and the same exact place for each pass.

It has to work. The computer will always know where the spindle is and where the carriage is and of course the crosslide. This is the way a manual geared lathe works. A cnc mill does the same thing when machining a small angle or ramp. X and Y start at one point and x and Y end in another. In a way that is what a thread is, a ramping angle wraped around a shaft.

If I got it wrong I hope someone tells me. Try doing a "Youtube" search. Other people must be threading like this.
Here it is, this shows you the idea of a stepper driven spindle:
http://www.youtube.com/watch?v=4r6amUUo90w

This is partly why I want to build a CNC indexer. I'll need it to make the timing pulley for the spindle. I'm thinking about mounting the large timing pulley to the 3-jaw chuck.
Jim

[John Stevenson]

Milton;





If I got it wrong I hope someone tells me. Try doing a "Youtube" search. Other people must be threading like this.
Here it is, this shows you the idea of a stepper driven spindle:
http://www.youtube.com/watch?v=4r6amUUo90w



Not quite Jim, that's being driven by EMC with a multiline encoder, still be using the same motor.
Mach can't do this yet.

Two problems I can see with using a stepper is the code and the stepper has to be big enough to actually remove metal.
the servo boys do this all the while but they are using high powered servo's, problem with steppers is the faster you go the less torque you have.

Second is the code, not impossible but you tell it so many revs for so far, then you have to retract, wind back, push fresh cut on, rinse and repeat.

[outback]

[QUOTE=
Second is the code, not impossible but you tell it so many revs for so far, then you have to retract, wind back, push fresh cut on, rinse and repeat.[/QUOTE]
Hey John: I figured using the stepper on the spindle, rewind back for the next cut would be required. Although couldn't the spindle stepper be reset to "0" between passes? John, do you think the concept will work? I realize it will not be perfect.
Appreciate the feed back though.

The control is basicly done. I still need to connect homing switches and a couple of minor things.
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/CNCLatheControl.jpg

Jogging the steppers with Turbocnc, (DOS). Mach III is not setup yet.
The area under the lathe stand is where the control cabinet and a tower computer will be set up. The shelf where the laptop sits is where the keyboard and monitor will be. The shelf folds down when not in use to
conserve floor space.
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/firstrun.jpg

Can anyone identify these connectors? (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/connector.jpg) These are used to disconnect the steppers from the control cabinet. Used these on projects in the past. Hey, they are reliable and cheap.

Next, get Mach III setup.
Jim

[DICKEYBIRD]

Those look like your basic 4-wire auto trailer light connectors to me.

[MaxHeadRoom]

Those look like your basic 4-wire auto trailer light connectors to me.

+1 on that one
Max.

[outback]

I have Mach3 working and I'm ready to tool up the lathe and start writing programs.

Video of X/Y axis running (http://smg.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/?action=view&current=XYVideo.mp4)
Video may take a minute to upload.

The complete setup (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Retrofitdone.jpg)

Now I'm looking for some lathe CAM software. Something real cheap.

Oh ya, you guys guessed it. The connectors are 4-pin boat trailer connectors.

Jim

[DICKEYBIRD]

Now I'm looking for some lathe CAM software. Something real cheap.Me three! I bought this http://www.cad2gcode.com/ last year and it looked like it would do the job for me for only $49.95 but I had trouble getting my TurboCAD .dxf's to work with it. I downloaded Draftsight and started trying to learn it but had to drop the whole thing and hand write code for the projects I had to get done by their deadlines. I'm going to give it another try later this year.

I'm told Lazy Turn from Mach works for many types of work but I didn't get anywhere with it for my projects. All the above problems are probably due to my ignance but I hope to have a breakthrough later when I have more time to invest.

The Denford looks really great Jim; you've walked through this project in a hurry! Can't wait to see it making parts.

[macona]

Your Y axis does not sound right. You might try adjusting the pot on the gecko drives to see if it quiets down.

A lot of things can be programmed through the wizards in Mach by splicing the resulting code together to make a full program.

Lazyturn is dead. Don't bother with it. Lathe CNC is considerable less popular than mill cnc so all the cams are more expensive. The two cheapest solutions I can think of are buying a used copy of TurboCAD with the CAM add-on off ebay and dealing with the sales guys at bobcad. You can get a copy for around $250-300 if you push it. They will give you a bunch of bs about having to talk the this manager but they will do it.

Lathe is much easier to program for though and a lot of the stuff I have done is just programmed by hand.

[outback]

I should be ready to cut threads in a few more hours. I'm using a 36 tooth
pulley on the spindle and a 16 tooth pulley on the stepper motor. This is a ratio of 2.25 : 1. If I calculated this correctly this should be 12.5 steps per degree of rotation. I assume this is better than a ratio that has a fraction of a step.

I just happened to have these pulleys on hand (in my junk) with a belt so that was enough inspiration to get this done. Next I found a place on the spindle to mount the 36 tooth (36XL037) timing pulley. The pulley is plastic but should work for testing the concept.

Here It is:
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/stepperthreading.jpg

If this works I'll make a thread cutting video.
Jim

[DICKEYBIRD]

That looks great Jim! I wish I had a dose of your speed & efficiency. You really plow through this stuff in a hurry.:eek:

How's the software part coming? Are you doing some kind of add-on code in Mach or ???

[outback]

I was back on the project as soon the the last of our Mothers day guests left.
It was a great day. Grilled steaks, launched model rockets and flew RC helicopters for the grandkids.

I was ready to go with lathe threading but could not get the 4th axis to work. Remember I had two Gecko 210's and one Gecko 202 in the cabinet. I worked until 11:00 PM last night trying to get the 202 driver to move a stepper motor, nothing. Moved wires around trying to see if all the steppers worked, verified wiring was good, boat trailer connectors were good. Moved wires from working steppers to the "A" axis to verify the "A" axis was working. Figuring the 202 driver was bad I ordered another 210 board on-line at 11:30 last night figuring I should have a spare anyway.

Back at this morning at 6:00 AM. Verified the 202 was working by installing it into another CNC project I had. The 202 was a good board. Finally set the 202 on top of a 210, lifted the terminal blocks off the 210 and installed on the 202 and still nothing. Ah Ha.....the 202 and the 210 are not interchangeable????? My older 202 drivers are using a different breakout board.

Called Marris at Gecko and he says the Gecko 202 needs 5VDC going to common and the Gecko 210 needs ground at the common. So now I have an Email sent to Bob Cambell designs to see what he says.

Eating leftovers from the Mothers day bash while I wait for a reply from
Bob Cambell.

Here is what he says:

"Jim,

The difference is in the voltage to power the optical isolators. The G210 can be either common ground or common 5 volts. The G210 has an internal jumper that can be set for either common 5 volts or common ground.

The G202 does not have an option. It will only work with common 5 volts.

Our breakout boards have a jumper that can be set for either common 5 volts or common ground.

If you will set the jumper in the G 210 to common 5 volts then the G210 will be the same as the G202 drives. The jumper on the breakout board will need to be set for common 5 volts.

Bob Campbell"

OK, I got it working!!!!!!!

Now try to thread

Jim

[outback]

This threading works the way I thought it would. Even with several passes the thread starts and stop and the same place. So the spindle does not rewind I used a G92 code to set A0.0. The program was for the spindle to turn 10 times or 3600 degrees and the carriage to advance .550 for 20 thread per inch. I worked quite well.
I can finally relax.

Here it is. Never worked with youtube.com before so I hope this works.
http://youtu.be/H1ybN8ZtlYY

Here is another short video of a single pass:
Single pass threading at photobucket (http://smg.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/?action=view&current=CNCthreadingshort.mp4)

Jim

[DICKEYBIRD]

That's slick! Did you write your G-code manually or??

[John Stevenson]

Jim,
Is the spindle stepper powerful enough to run steel threading say 8 or 10 tpi ?

[outback]

Jim,
Is the spindle stepper powerful enough to run steel threading say 8 or 10 tpi ?

The stepper running the spindle is a 450oz/in stepper geared down 2.25 : 1.
What you see in the video is my very first CNC machined thread in delrin plastic. I rather doubt it could cut a 10 tpi. Those chips will be fairly wide.
Although with multiple passes anything is possible.

After I got this working I was thinking tapered threads would be easy to cut.
This is my first experience with angular settings on stepper motors. I set it to 12.5 steps per degree and it work perfectly

Below is the code I wrote after I made the video. It makes 5 passes now and the tool withdraws gradually at the end of the thread last thread on each pass. Notice it is all done in rapid feeds. Not sure if that is right or wrong, just worked out that way.

For a 5/8 - 18 thread

G00 X.3125 Y0.0 {OD and end of piece}
N0007 G00 A0.0
G00 A3600.0 y.5555 {cut the thread}
G00 x.45 {retract tool}
G00 y0 {return tool to end of piece}
G92 A0.0 {reset "A" axis to 0.0}
G00 X.295 Y0.0 {minor diameter of thread}
G00 A3600.0 y.5555
G00 A3960 Y.611 X.450 {cut one more thread and retract tool at the same time}
G00 y0
G92 A0.0
G00 X.290 Y0.0 {next thread, minor diameter .290}
G00 A3600.0 y.5555
G00 A3960 Y.611 X.450 {cut one more thread and retract tool at the same time}
G00 x.45
G00 y0
G92 A0.0
G00 X.289 Y0.0 {next thread, minor diameter .289}
G00 A3600.0 Y.5555
G00 A3960 Y.611 X.450 {cut one more thread and retract tool at the same time}
g00 x.45
G00 y0
G92 A0.0
N0025 M09
N0029 M05
M30 {rewind CNC program}
M02
Jim

[DICKEYBIRD]

Below is the code I wrote....Well that leaves me out of this game!:eek: Someday maybe; but I doubt it.:o

Very nice work Jim.

[outback]

Well that leaves me out of this game!:eek: Someday maybe; but I doubt it.:o

Very nice work Jim.

The way my lathe is setup X is the crosslide and Y is the carriage.

Y0.0 is the end of the piece and X.312 is the OD.

Next, to cut 20 tpi, the pitch is .050. To cut 10 threads Y will need to move
.500 or Y.500. "A" (the chuck) will need to turn 10 times or 360 X 10 = 3600 degrees.

First line of code. X.312 Y0.0 {tool is at end of piece}
next line of code X0.300 {depth of cut first pass}
next line of code A3600 Y0.500 {first thread cut}
next line of code A 3960 Y0.550 X.312 {cut one more thread and retract tool from thread}
next line of code Y0.0 {return tool to end of piece}
next line of code G92 A0.0 {reset the A axis to 0.0} {or unwind to 0.0}

To Repeat copy and past the same code for each pass changing only X for depth of thread. It is quite easy.

Jim

[macona]

So, why are you messing around with the stepper motor for the spindle and not just use an encoder for EMC or index mark for Mach?

[outback]

I have no idea how to do that. Somehow I got the idea MachIII would not
do thread cutting.

I attended some discussions on EMC at one of the CNC workshops and I think I have a EMC disk somewhere. Never looked at it on my own. I have a computer I could be using on EMC. If I remember correctly EMC does not run in WINDOWS.

Enlighten me Macona. I would much rather be using an encoder than a stepper. To thread with the stepper motor I have to stop and install the timing belt. Another concern is if I ever power up the lathe with the spindle motor and that timing belt is still on the stepper it could be bad news for the Gecko driver board.

Ah yes, I did find the EMC2 disk. Tell me what I need for an encoder? Will EMC2 run on a laptop?

I'm all ears.

Thanks,
Jim

[DICKEYBIRD]

From what I've read lately, Mach's threading now works well for some users, not so well for others. There's video proof that it does work for many folks.:)

The limiting factor is that it can only handle the input from a single slot speed sensor wheel and if the spindle speed varies too much, the threads get wacky. I think it'll work fine for relatively short thread lengths using some extra lead-in distance. Funny, in reading old posts on the Mach forum, the early versions would work with multi-slot sensor discs???

I think the new Mach4 is supposed to do it differently, whenever it's available. I'm going to spend some time with Mach threading when I get my ORAC running.

[MaxHeadRoom]

The problem with Mach it is not a true closed loop system, with a true closed loop back to the controller the Z axis can be geared off of the Spindle encoder, as is done with DSp controllers such as dedicated multi-axis motion cards and the likes of Dynomotion/Kflop.
Max.

[outback]

The Mach3 website has a download manual that is all about threading. About 60 pages long. I'll read it over this weekend.

If Mach3 will cut short threads then I should be fine using it. I can't see
myself doing large lathe work. If I do see large work I have a JET 13 X 40 manual lathe. Most of The lathe work I see is under 1" dia and less than
2" long. The main reason I bought this 8" CNC lathe.

My shop is somewhat dedicated to small work. I have no lifting equipment
at all. If I can't carry by hand a finished job from the shop to my pickup truck I generally do not accept the job. My back is in great shape and want to keep it that way.

http://www.machsupport.com/docs/Mach3_Threading.pdf
Jim

Jim

[skunkworks]

(I am a linuxcnc guy)

It may be easier for you to find a way to mount a single index sensor somewhere on the spindle. mach and linuxcnc will work with a single index. Linuxcnc though lets you use an encoder (A,Z or A,B,Z) Z is the index and a or a,b are the higher number of pulses per rev. That gives you better sync between the spindle and the axis. With a A,B,Z encoder you could also rigid tap. (the B channel give you quadrature counting which allows emc to also know which direction the spindle is turning also.

This is what higher counts per rev gets you...

http://www.youtube.com/watch?v=AW5-A_ru3-I&feature=plcp

You already have a way to mount an encoder and drive it (where you mounted the stepper motor to run the spindle.) You would just need to gear it 1:1.

I would get a 100ppr encoder with index (or there about) at 100 ppr that is 400 counts quadrature. On a decent computer running linuxcnc and counting on the printer port - you should be able to thread at least to 2000rpm. (there are also pretty inexpensive hardware interface solutions for linuxcnc that move the encoder counting and step generation out of software into hardware)

Information overload?

sam

[skunkworks]

(if I was using a hardware solution with linuxcnc (mesa, pico systems, whatever) I would then get a much higher count encoder >=1000 line..)

[outback]

I have a bunch of proximity sensors in the basement. Could I make a plate with 100 equally spaced holes and use that with a sensor for an encoder?

Can you recomend an encoder Make and model number? Probably a bunch on Ebay.

My breakout board has a connection for an encoder.

Why do you like EMC software? Right now I'm using Mach3 and TurboCNC software. Turbocnc runs in DOS but it also runs well on old WIN 98 laptops.
I ran a job this morning on Turbocnc.
Thanks, Jim

[skunkworks]

I started with turbocnc and when to linuxcnc when I needed blending. After that it was love. :) I initally used it because it was free (I am cheap) but stayed with it because it has done everything I have dreamed up so far. It has been rock solid. The last thing we converted was a large hmc with all the bells and whistles. (tool changer, 16 speed spindle, pallets, indexing table..) All the configuring was done within linuxcnc. (between its HAL and integrated ladder.) (Mesa interface harware)

http://bbs.homeshopmachinist.net/showthread.php?t=54220

I have not used mach so can only go by what I have read.

as far as the prox sensors I would do some looking. (I don't know) you can get encoders pretty cheap though off ebay. New ones from automation direct are not too bad either.. digikey sells some magnetic ones that you would have to build an assembly for - but they are around $30 and work with many shaft sizes and have configurable PPR

sam



I have a bunch of proximity sensors in the basement. Could I make a plate with 100 equally spaced holes and use that with a sensor for an encoder?

Can you recomend an encoder Make and model number? Probably a bunch on Ebay.

My breakout board has a connection for an encoder.

Why do you like EMC software? Right now I'm using Mach3 and TurboCNC software. Turbocnc runs in DOS but it also runs well on old WIN 98 laptops.
I ran a job this morning on Turbocnc.
Thanks, Jim

[outback]

Finally got back to my Denford lathe retrofit project. While threading with a stepper motor powered spindle was cool it was slow and did not have the power to cut steel threads so I set out to mount an encoder to the spindle
and use Mach3 for threading.

For an encoder all I needed was an inexpensive OPB 916B sensor and a plate mounted to the lathe spindle with one slot. All Mach3 needs is a disk with one slot for the encoder. Mach3 takes the average of 8 revolutions and determines the RPM from that. Just about any industrial sensor can be used as long as the output is NPN. Most industrial sensors I have worked with operate in the 10 to 30VDC range so the 12V terminals are fine.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Lathetachometer.jpg

The challenge for me was to get the output from the sensor into the breakout board. There was a J23 connection intended for the encoder inputs but I could not figure out how to get it to work. Woke up this morning with an idea. Since I'm not using the "A Home" connector I wired up the sensor to those terminals. +12V, GND and sensor terminals were already there.

Went to Ports & Pins in the Mach3 configuration and set the INDEX input to
"active" Port 1 and PIN 15 and then "Active LOW". Next, I went to the diagnostic screen and I could see the INDEX light turn ON & OFF as the slot in the disk passed through the sensor. Mach3 has made this encoder simple and inexpensive to set up.

Started the spindle from Mach3 and the RPM display starded to show numbers.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/TachDisplay.jpg

I checked the RPM display in Mach3 with a handheld tachometer and they both agreed within 1% or better.

I think I'm ready to cut threads again. I'm having a great day.
Jim

[DICKEYBIRD]

Great, more progress! Keep it coming; it helps keep me motivated on mine.:) Make sure and let us know how Mach3 threading works...I'm hoping it works well for you.

Mine's slowed down to a standstill lately due to pesky little paying jobs. I have several that are eating up my spare time for not a lot of money but are for the 2 buddies that have given me almost all the jobs I've had over the past 2 yrs. Gotta give & take a little.

I did get the spindle motor & relay hooked up & working under Mach control but danged if I can get it to control the spindle speed via the CNC4PC C11 B.O.B. and KB speed control. It just starts up at full speed with no control up or down. Probably a setup mistake on my part. I hope to get back on it for a while tomorrow evening and find out what's wrong. Just another piece of the puzzle to solve.

[outback]

Tonight I cut threads with Mach3. This is the most amazing thing I have seen or done.

My first CNC cut thread;
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/CNCthreads.jpg

I cut the threads at 300 RPM. I tried going faster but I think my carriage stepper had a max speed setting to slow for threading at 600 RPM. So I did my threading at 300 RPM.

The G76 line of code works like magic. The pitch, depth of cut, depth per pass is all listed in the code. My very first thread was way oversized when the thread should have been finished. I measure the threads with thread measuring wires and found the thread pitch-diameter was still .010" oversized.
I went to edit the G76 line of code and simply increased the depth of cut(Minor dia.) by .010 and ran the program again and the gage nut spun onto the threads with very little play. I never would have thought a single pulse per revolution would work so well but it does. I ran the program several times after making some changes and it was not problem for the lathe to pick up the previously cut thread.

A poor video, I'm working on a better one (http://www.youtube.com/watch?v=YOg-8xI32VY&feature=youtu.be)

CNC threading is probably easier than cutting threads on a manual lathe. Threading to a shoulder did not appear to be a challenge for Mach3. No lines to engage a plit-nut onto. The software and the encoder did all that while I watched

Mach3 has a "Simple Threading Wizard" that I'm going to experiment with next but entering all the variables on the G76 line of code seemed easy enough for me.

Next, I'm going to learn how to pick up and existing thread then learn how to CNC cut internal threads.

[John Stevenson]

Jim,
Just as an experiment do a long thread say 4" long and a decent pitch like 16 tpi
Then lay a piece of all thread along side it to check for pitch error.

In fact find the all thread and match the pitch instead of 16 tpi, easier.

The single slot method has problems over long lengths, for some more than others. Because many only do short threads they often don't realise this.

John Damyer who makes the ELS has just found this out and altered his code.
Nothing can be done in Mach3 because of how it's written, it would require a complete rewrite to cure it but fortunately that is what is happening in Mach4 at the moment.

Although Mach4 is written by Brian Barker and his team it is still up to Art Fenerty to write the core driver code.
Knowing what he knows now, 5 years on from Mach3, Art thinks it's fixable.

I'd be interested to see close ups of the thread towards the end.

[outback]

John;

I would not use threaded rod as a thread gage. I used some 1/2-20 threaded rod as a feedscrew in my first CNC mill. I think it was off .040 or .050" in 6". I would be better off checking my lathe threads with an eyeglass and steel scale.

I would doubt the threads cut by Mach3 would be very close over a 3 or 4" length. I don't see how they could be . I'm surprised cutting threads with Mach3 works as well as it does with a single pulse per revolution. However, I did check the cut threads against a ground tap and could not see any error with the naked eye. The nut and thread engagement had a good feel.

I think cutting threads with a 100 or more pulse encoder would be a different story or better yet cutting threads on a lathe with a leadscrew.

But lets be realistic. Screws are engaged with threads in a tapped holes by
1 1/2 or 2 times the screw diameter. If the threads don't bind in that distance I would say we have a keeper.

In addition my encoder cost me $5 out of pocket and the Mach3 software cost another $175. I'm quite pleased with the threading results considering the cash investment I have made and I'll bet I'll make money with this setup.
I have less than $1800 in the entire project.

New video shot this morning (http://smg.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/?action=view&current=CNCthreading4.mp4)
Jim

[DICKEYBIRD]

Man, that looks great Jim! Now you can whip out an ER-32 (or 40) collet chuck whenever you want. The taper and 1.5mm threads should be easy-peasy. A self improving lathe; I love it!:D

I'm giving up on the Mach/C-11/KBIC speed control issue for now on mine as it's just eating up my spare time. I'll get back on that later...manual speed control via external pot will do fine for now.

[John Stevenson]

Jim,
Not having a pop at you it's just that Mach works different ways for different people.
It's a complex mix and computer and machine.

Couple of years back i spent a whole week doing nothing but threading and reporting back to Art, try a new driver, rinse and repeat.

It's not a question of a nut having 1.5 to 2D length but more about the thread deteriorating over it's length and believe me a piece of al thread is accurate enough.

This is a classic example.

http://www.stevenson-engineers.co.uk/files/day9test1.jpg

just two passes but you can see that after the first short length it's starting to go out of pitch but different error on each pass with the result that the last bit of thread is useless.

It's all down to the single pulse, Mach can't use a multi line encoder [ yet ] so we are stuck with it and it is the pulse.

EMC can use a multi line encoder and it threads perfectly and accurately.

I use my cnc for some threading production jobs but they are only 10mm [ 3/8" ] long and they come out OK.

[outback]

John;

I just ran a test where I cut 10 TPI over 5". I figure .100 per thread would be an easy measurement. I made the cut in 2 passes just deep enough to scribe a line. The second pass followed the first pass so perfectly it removed
no material.

With an eye glass and steel rule I can see the last thread was off about .010"
I really expected much worse. Either I got lucky or it works darn good.

However, I did calibrate the Z axis from the "settings window". It came out
to 4067.7 steps per. Before I calibrated the lathe it was off by half a thread
in 5". People with error may need to calibrate there machine.

Milton:
I figured speed control was going to eat up more time than it was worth. I'm not using homing or limit switches for the same
reason. I'm taking this project to a point where I think I can make money with it and no further. The computer does start and stop the spindle though. Maybe someday I'll set it up with auto coolant.


I would post a picture but I'm getting ready to leave for vacation.
Jim

[loply]

I'm very interested by this discussion as I'm slowly working my way towards converting a Denford Viceroy to CNC.

I had planned to use Mach3 but after this thread think I'll go with LinuxCNC instead. One of the main things I'll do with it is relatively long threads...

[DICKEYBIRD]

I had planned to use Mach3 but after this thread think I'll go with LinuxCNC instead. One of the main things I'll do with it is relatively long threads...
While you're getting it up & working smoothly with EMC, make sure & take lots of notes so you can train me how to make it work.:)

[DICKEYBIRD]

Wow, just noticed your location. Are you in Yorkshire anywhere near sunny Brighouse where the Denfords were built?

[outback]

Here is a pic of the threads and a steel rule to show how well mach3 did after 2 passes. I thought Mach3 did a great job, better than I expected.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/CNCThread.jpg

large pic 5" of threads (http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/longCNCthread.jpg)

Jim

[John Stevenson]

Very good results Jim.
In the big picture you can see the start of it widening the threads on the last inch.

As I say it's very machine and computer dependant, the people having the most trouble are the ones with the mini lathes where the spindle HP is lacking and any deviation in speed affects the thread.

If I was getting these threads I'd be very happy as it's rare for a CNC lathe to have to do long threads, most are just short fixings on turned parts.

Edit to say one of the best mods you can make to a conversion is to overpower the lathe if possible to keep a constant spindle HP.

[outback]

Man, that looks great Jim! Now you can whip out an ER-32 (or 40) collet chuck whenever you want. The taper and 1.5mm threads should be easy-peasy. A self improving lathe; I love it!:D
.

That brings up a great question. How is this lathe set up with collets?
A 5C collet would be to large. Has it ever been done?

Jim

[DICKEYBIRD]

I've seen 5C chucks installed on Emco C8's but the spindle has only a 20mm hole so what's the use? Plus they're so BIG to go on such a little feller.

I put a flanged style ER32 chuck on my C8 clone years ago & love it. I bought another one to go on the Denford. They have to be modified to fit but it's no biggie. I also bought a Maritool ball bearing equipped collet nut to go with it.

Here's one like I bought recently although it's a few dollars higher than mine. http://www.ebay.com/itm/ER32-COLLET-CHUCK-FIXTURE-A834-/400306916665?pt=BI_Tool_Work_Holding&hash=item5d3426cd39 Can't seem to find a link to the other supplier right now. His was $29.99 + $10.50 shipping. His didn't come with a wrench but I had extras already. Hard to make one for that price and the quality is good.

I'm going to bore the backside oversize on the new one to give it plenty of wobble room and drill & tap 4 holes around the perimeter & install 4 brass tipped setscrews to make it a poor man's set-tru rig.

The paying work I'm getting lately involves repairing/modifying existing small parts that aren't necessarily straight & true so I have to be able to dial-in a feature precisely before cutting. The ER collets leave no marks like a 4-jaw can and they grip like the dickens but I can still dial in individual parts as needed. Slick, eh?:)

[EVguru]

Very good results Jim.
In the big picture you can see the start of it widening the threads on the last inch.

As I say it's very machine and computer dependant, the people having the most trouble are the ones with the mini lathes where the spindle HP is lacking and any deviation in speed affects the thread.

I still think it may be worth adding a speed feedback to a VFD. Most (even the cheap Chinese ones) have a built in PID function that accepts a 0 or 4-20mA input that could be used with a suitable encoder (certainly better than one pulse per rev).

[John Stevenson]

My Orac has an air chuck fitted but the original 3 jaw is in the tray.

[outback]

I still think it may be worth adding a speed feedback to a VFD. Most (even the cheap Chinese ones) have a built in PID function that accepts a 0 or 4-20mA input that could be used with a suitable encoder (certainly better than one pulse per rev).

Paul;

Do you know how to do all this? What you suggest may require a different
breakout board and different software other than mach3.

All you need to do is tell me what spindle speed control to get, what encoder to get and what software to get and how to connect them and I'll do it.

Jim

[EVguru]

Paul;

Do you know how to do all this? What you suggest may require a different
breakout board and different software other than mach3.

All you need to do is tell me what spindle speed control to get, what encoder to get and what software to get and how to connect them and I'll do it.

Jim

It has nothing to do with the software, it's all done in the VFD.

If the spindle speed was stable enough, then the single input pulse to Mach wouldn't matter.

You ask the drive to run the motor at a set frequency, but that doesn't mean a fixed motor speed. Induction motors operate with a slip angle and that angle is proportional to torque. With feedback the VFD can increase the frequency to keep the speed constant until the slip angle is too great and the motor torque starts falling.

It needn't be speed, you might want a drive to power a take up reel and keep tension in a cable constant.

The VFDs I've looked at have a voltage input for frequency control (or it might be set via a comm port, or from up/down buttons) and a current loop input for feedback. That's usually a 0-20mA or 4-20mA input, which is a standard for many industrial sensors.

You can buy off the shelf current loop sensors like this for example http://www.sensoronix.com/products:linear-output-4-20-speed-sensors

[Hood]

You will likely end up with worse threading if you allow the VFD to try and compensate for spindle slowdown in threading. People have found they get better threading if they turn any such compensating feature, in their VFD, off.

The reason is the VFD sees the slowdown and tries to keep the spindle speed constant, this may be ok for normal turning but for threading it is not good. Mach sees the spindle slow so slows the axis but the VFD increases it so it ends up jumping all over the place.
Hood

[outback]

I've seen 5C chucks installed on Emco C8's but the spindle has only a 20mm hole so what's the use? Plus they're so BIG to go on such a little feller.

I put a flanged style ER32 chuck on my C8 clone years ago & love it. I bought another one to go on the Denford. They have to be modified to fit but it's no biggie. I also bought a Maritool ball bearing equipped collet nut to go with it.

The ER collets leave no marks like a 4-jaw can and they grip like the dickens but I can still dial in individual parts as needed. Slick, eh?:)

Milton; I'm going to make one of those when I get back from vacation. I have one of those on an R8 shank that I bought and never use. I'll have the nut and a few collets.

I would like to turn the collet taper on the lathe itself to minimize runout. I hope the ER collets are cheap.
Jim

[John Stevenson]

You will likely end up with worse threading if you allow the VFD to try and compensate for spindle slowdown in threading. People have found they get better threading if they turn any such compensating feature, in their VFD, off.

The reason is the VFD sees the slowdown and tries to keep the spindle speed constant, this may be ok for normal turning but for threading it is not good. Mach sees the spindle slow so slows the axis but the VFD increases it so it ends up jumping all over the place.
Hood

Fully agree with Robin.

I have probably what is the worse CNC lathe ever made.
It's a Sieg KC4 and is powered by one of their brushless servo motors. Inside this motor is an encoder that talks to the spindle board.
Say you set for 900 revs, stick a cut on and the revs drop to say 880 but it senses this and increases power and you are back up to 900, seems perfect and probably is on a manual machine which this is what it started life as.

However on the CNC you now have two closed loops that are not connected.
As the revs drop Mach senses this and compensates but the spindle board has already done the same job so both loops fight one another.

What it needs is to scrap the brushless servo and fit afar larger motor that has no control loop.

Two things stop me, one is hardy any room to fit a larger motor into the nicely made enclosure and the main reason is if we can get Mach to work with this machine and thread perfectly then any machine should be able to do the same.

Having the worlds worse lathe is actually an advantage when testing. :rolleyes:

[outback]

You will likely end up with worse threading if you allow the VFD to try and compensate for spindle slowdown in threading. People have found they get better threading if they turn any such compensating feature, in their VFD, off.

The reason is the VFD sees the slowdown and tries to keep the spindle speed constant, this may be ok for normal turning but for threading it is not good. Mach sees the spindle slow so slows the axis but the VFD increases it so it ends up jumping all over the place.
Hood

I saw what you describe by changing the spindle speeds in the middle of a thread cut to see if that would screw up the thread cut. It did. Mach3 started cutting a finer pitch thread but very quickly got itself back in time.

My Denford lathe has the original 1/2hp 3 phase motor. If the motor slows because of chip load the best solution is a slightly larger spindle motor or a reduced chip load.

I'm 100% satisfied and thrilled with the way my CNC lathe cuts threads. If I need to cut a thread my 8" lathe is not capable of I have a Nice 13 X 40 JET lathe 3 feet away.

I plan to very small parts in my Denford lathe and I think it will work fine.
Jim

[John Stevenson]

I have a reduced frame 1.1kw 3 phase motor here, that's 1 1/2 HP to the unwashed, that I aim to fit to the Orac when I start the conversion purely to get spindle revs stability.

These reduced frame motors are basically a larger motor in the next size smaller frame and as such isn't that much bigger than the older original motor.

If you want compact motors look for the metric framed ones they tend to be smaller than the imperial framed ones.

http://www.stevenson-engineers.co.uk/files/bridgy_motor1.jpg

As an example 1.5 HP Bridgy motor on the right. 2 HP metric frame motor on the left. These are standard motors, in a reduced frame that blue one would be 3 HP.

[EVguru]

I have probably what is the worse CNC lathe ever made.

Say you set for 900 revs, stick a cut on and the revs drop to say 880 but it senses this and increases power and you are back up to 900, seems perfect and probably is on a manual machine which this is what it started life as.

However on the CNC you now have two closed loops that are not connected.
As the revs drop Mach senses this and compensates but the spindle board has already done the same job so both loops fight one another.

I see exactly what you're saying, but that's clearly not a tuned control loop on the spindle.

If it's possible to get the spindle tuned to respond in a fraction of one revolution what then?

I admit that that may not be possible without overshoot or oscillation, but since the only thing I'll need to make is a frequency to voltage converter circuit (and I think there's one on the shelf at work) I think it's worth experimenting.

[loply]

Surely the simple solution here is to fit a grossly overpowered motor and do your threading in a lower gear ratio than you otherwise would?

Or would even an unnecessarily powerful motor experience lag betwixt slowing down as the cut begins, and speeding back up?

[Hood]

Surely the simple solution here is to fit a grossly overpowered motor and do your threading in a lower gear ratio than you otherwise would?

Or would even an unnecessarily powerful motor experience lag betwixt slowing down as the cut begins, and speeding back up?

The solution here is to try it and see and you will likely be pleasantly surprised (like Jim has been) at how well your threading turns out. Of course if you have the second worst CNC lathe ever made (John has the worst he says ;) ) you may not, but you have very little to lose by trying.

Hood

[John Stevenson]

Very true what Robin says, well worth a try.

The machines that seem to suffer most are the smaller mini lathes with the Dc motors. After all these lathe are a compromise on features against price.

However if you do what Robin has done and fit a 14 KW motor driving thru a 14 speed box than you will have no problems.
Robin can switch the lathe off half way thru a thread and the momentum will finish it :D

Seriously this is what is all about, a consistent speed.

[Hood]

However if you do what Robin has done and fit a 14 KW motor driving thru a 14 speed box than you will have no problems.

Originally the lathe had a 11KW induction motor driven through a gearbox with electromagnetic clutches. I was then lucky to get a new AC servo and a 22Kw servo drive for £250 and £180 respectively. The servo is rated as 12.5Kw but that seems to be conservative as taking constant torque (83Nm) and rpm (2000) it actually works out at 17.5Kw However even at that it probably works out a huge amount less torque at lower speeds than the original motor had going via the gearbox (servo is direct drive)




Robin can switch the lathe off half way thru a thread and the momentum will finish it :D
Not true John, if you cut the drive power it slows down rapidly when you are taking a 10mm DOC on 4inch dia EN8 ;)


Seriously this is what is all about, a consistent speed.

I would say not actually consistent speed but rather if there is a slowdown it is consistent, ie your spindle drive doesnt try to correct, lots of people with smallish motors that seem to thread fine.

Hood

[outback]

Today I made an ER collet chuck for my Denford lathe. I used the collets and a collet chuck nut from an R8 shank ER collet system that I bought and never used. I was surprised the nut had a ballbearing thrust bearing for pushing the collet into the tapered hole.

I'm pretty disapointed in the out come. First, I spent all day working on the thing. I need to fiddle with it so it has the least runout and the ER collets do not seem to release the part. There must be a better collet somewhere to make a collet chuck. It does look kinda cool but I can see my self cussing at this thing forever.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/ERcolletchuck.jpg

I think the outcome of the collet chuck would have been better if everything had been ground. Instead it was all made on my 13" JET lathe.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/ERcolletarbor.jpg

Has someone made one of these and happy with the outcome.
Jim

[DICKEYBIRD]

Looks great Jim. Sorry to hear you're not happy with it. It looks like you've got the collet seated in the nut properly so it's supposed to pop the collet out when you loosen the nut a few turns.

I hate to ask but you are "popping" the collet into the nut before screwing it onto the chuck? The eccentric shape of the inner portion of the nut requires the collet to be popped in with a sideways rocking move. I have heard of some mis-built bearing equipped nuts that don't work right even if the collet is snapped in right.

I have an extra regular nut and will be happy to send it tomorrow if you want it.

[outback]

Milton;
Yes, I'm inserting the collet into the nut first thing. Like you said, the nut pulls the collet out of the taper.

The collet chuck was not easy to make. As you probably know, the Denford lathe spindle has a tapered hub. I had to hand fit the collet chuck to the spindle. Then the threads for the nut needed to be cut and the threads need to be concentric. I tried cutting the threads on the Denford lathe but that little 1/2hp motor didn't have the power so I cut the threads (Metric) on my 13" JET lathe. I tried cutting the collet taper in the Denford lathe thinking at least the collet taper would be concentric to the lathe spindle. My triganometry numbers must have been off becuse that didn't work either.
I ended up cutting the collet taper in the JET lathe as well using the compound rest.

All the features of the collet chuck need to be concentric to the lathe spindle
mounting and it is doubtful any of mine are concentric.

I wonder if I could buy an adaptor plate for the Denford spindle?

I'll do some more thinking. Maybe I'll try to make another one.
Jim

[DICKEYBIRD]

All the features of the collet chuck need to be concentric to the lathe spindle
mounting and it is doubtful any of mine are concentric.

I wonder if I could buy an adaptor plate for the Denford spindle?
Jim, go back to post #69 on this thread and take a look at the ER32 chuck I linked to there.

I gave up on trying to get a perfect mountup of the collet chuck to the tapered spindle nose on my C8 clone due to the small amount of runout that's inevitable in the collets I can afford plus the type of work I've been doing requires a precise dial in. I bored the back of the collet chuck flange out about .040" larger than the spindle tapered nose and bump/dial it into very close concentricity as the 3 flange bolts are tightened.

My ORAC will have the same setup but will have 4 tapped holes around the perimeter of the chuck flange with brass-tipped screws bearing on the spindle nose for precisely adjusting it. I did a similar thing on my Denford MicroMill/Lathe mod and it works amazingly well. 2nd picture, post #3 here:
http://bbs.homeshopmachinist.net/showthread.php?t=50982&highlight=POOR+MAN%27S

[outback]

Milton;
Been thinking about this all day while working on a paying job. I may start over on another collet chuck.

I'll turn the threads and bore the collet taper in one setup first thing. That much will be concentric. Machine the tapered hole to match the taper on the Denford spindle last instead of first.

If the this setup still has objectionable runout I have an Idea for an adjustment on the order of what you have but still different.

I'm amazed at the ER collet chuck with the R8 shank. The Chinese did a nice job on it. Kinda why I want make another one and get it right.
Jim

[DICKEYBIRD]

I'm amazed at the ER collet chuck with the R8 shank. The Chinese did a nice job on it. Kinda why I want make another one and get it right.Yep, it's amazing how beautiful the stuff available direct from CTC is for the price.

Only problem I've had with them is with the R8/ER32 chuck I bought to replace the one I hacked up to make the adjustable chuck in the other thread. I didn't bother checking the new one for runout until just the other day. The one I hacked up had maybe .0002" before cutting it apart, the replacement one has .0015":(

I'm not to upset about it as I rarely use it in the mill anyway. I mount endmills and larger drills straight into R8 collets & smaller drills go into a straight shank ER16 collet chuck mounted in an R8 collet.

[outback]

Ya know what they say, "The second one gets done in half the time".

The second collet chuck got done in about 3 hours. I bored the tapered hole for the collet first thing then cut the 48mm X 2.0 thread. Carefully faced off the flange and made a reference cut on the OD of the flange.

Then bored the tapered hole to match the tapered hub on the Denford spindle. I used the reference cut to indicate the previous work concentric with tapered hole.

One important thing I did was to surface grind the flange that mates with the lathe spindle. If the flange is out of square the collets will not be concentric even if everything else is perfect. I used magnetic parallels to hold the collet chuck with the threads facing downward. It still took .005" to clean up the flange.
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Flangegrind.jpg

Set it up in the lathe. Close to the collet I had .0001 runout and 3/4" away from the collet I had .0006 runout. The adjustment is on hold for now.
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/ERcolletchuck2.jpg
Jim

[DICKEYBIRD]

That looks great Jim. You did more work in 3 hrs. than I'd get done in a week!

48 x 2.0mm...that's ER40 right? Cool:) !

[outback]

I guess the proper thread designation would be M48 X 2.0.

ER40
I was wondering what size ER collet that was.

I should get ambitious and make CAD drawings of the collet chuck.

I'm thinking about a collet chuck for DA 100 collets next.
Jim

[DICKEYBIRD]

Wow, that's strange! I just looked up the ER40 specs and Rego-Fix says the thread is M50 x 1.50. I wonder what the heck you've got there?

I knew your M48 x 2.0 was bigger than my ER32's M40 x 1.50 so assumed yours was ER40. ER50 is M64 x 2.0 Maybe an ER45?

[outback]

OD of thread was 47.87MM so I figured M48.

No identification on the R8 shank. The nut is marked SHIN-YAIN EOC25. One collet says SYIC. I think I bought this as a set from ENCO around
2002 for around $100. It is very high quality so I'm thinking the origin could be Taiwan. The nut has ground threads. Not likely it is Chinese.
Jim

[uncle pete]

For what it's worth, My Bison ER-40 milling chuck shows 49.89 mm over the thread crests.

Pete

[outback]

I don't think I'm using at ER collet but a TG100 collet instead. I have spent an hour looking for a TG100 collet drawing will little success. I know the taper I cut was 2.72 degrees with the centerline. Most ER collets use 8 degrees with the centerline or 16 degree included angle.

If someone has a drawing of the TG100 collet I would appreciate seeing it.
Jim

[ammcoman2]

This may help

http://shopswarf.orconhosting.net.nz/sindex.html

Geoff

[tlfamm]

SYIC has production facilities in Taiwan, Thailand, and Vietnam

http://www.syic.com.tw/



collets, etc here (click on "Accessories")

http://www.syic.com.tw/product.htm

----------------------------------------------

Some if not all of these Grizzly products are produced by SYIC:

http://www.grizzly.com/catalog/2012/Main/652


[That is, the "Txxxxx" and "SBxxxx" part no's]

[outback]

The collet used in my collet chuck is a SYOZ 25. Collet Overall length 52MM and the largest diameter 35MM.

I would say this a Bastard size collet. I will not be buidling tools around this type of collet. At least I can use what I have.

Here is the link;
http://www.techniksusa.com/wood/din6388.htm

The collet has a slight taper, small end 29MM. Must be for griping endmill shanks.

Jim

[outback]

The finish touch, Cover for the pulleys.

http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Pulleycabinet.jpg

Follower rest;
http://img.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/Followerrest.jpg
Jim

[DICKEYBIRD]

Looks great Jim! Where'd you get the matching paint for the cover?

Not sure I'm going to use the pulley cover that came with mine. I'm fighting a vibration problem and have installed an idler pulley that gets in the way. At 1300-1400 rpm, the spindle housing shakes noticeably. I added the idler and a triangulated brace from the top of the housing down to the far end of the motor plate and it still shakes. I haven't got my toolholder mounted so no tests yet to see if the finish is affected.

The visibly lumpy 370-J-10 belt I got online was made in India and may be what's wrong though. All the mods made no difference but in desperation I loosened the belt way up and the vibes diminished a lot. I have a proper Gates belt on the way and hope that fixes it. Penny wise and pound foolish!

Are you happy with yours as far as rigidity, finish and repeatability?

[outback]

Milton;

The paint came from Ace Hardware and was packaged in a plastic jar. Color is called "Emerald City",
B37-6. It is almost a perfect match.

Thus far I love the Denford lathe but I have not ran it much yet. I'm setting up a production job now and will have a more firm opinion about the lathe when done. I think the 1/2hp spindle motor runs to slow and lacks power on larger diameter stuff. I think a 3/4hp would be better. The job I have now is turning and grooving 3/16 dia 17-4 stainless. It does a nice job machining stainless. It has been a struggle because it is my first experience running a CNC lathe that I'm not familiar with. It seems to repeat well and gives a great finish. The job I have is probably a perfect match for the Denford lathe.

Been making chips for over 40 years and never used a follower rest until yesterday. The follower rest made a big difference.

I like the way I have the lathe setup where Mach3 starts and stops the spindle and I like Mach3 to. I also like how quiet the lathe runs.

I'll post pictures next week of the parts I'm running. Been real busy the last 3 weeks on paying jobs with work for 4 different customers in the shop. I made a little transmission for one customer. Fun but glad to see it go out the door. If nothing else comes along I should be caught up next week with paying jobs then I can play, play, play.
Jim

[outback]

Internal threading with Mach3

Click here to see the video (http://smg.photobucket.com/albums/v30/jglass/CNC%20projects/CNC%20Lathe/?action=view&current=insidethreading.mp4)

Jim

[DICKEYBIRD]

Hey Jim, I was searching for this old Doc Nickel thread for another purpose and the light bulb lit up! Why not graft one of these onto your stepper driven spindle setup? http://bbs.homeshopmachinist.net/threads/24891-Threading-with-a-treadmill?highlight=threadmill You're just the kind of guy that'd have it up and making beautiful parts in no time.:D