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View Full Version : Not CNC yet but it's a mill.



Evan
09-23-2006, 07:59 PM
I've been busy adjusting and doing a bunch of fiddly things on my mill and finally today took some real test cuts. It's strictly manual so far but I have the motors mounted. I still need to mount and wire up things like limit switches and build the interface, driver box and power supply.

These are a couple of test cuts I just did today. These are aluminum only as I haven't yet made the linear bearing felt holders. I don't want to get steel chips in the bearings.

First is overview of setup:
4" round of 6061, facing cuts about .025" deep.

http://vts.bc.ca/pics/milltest1.jpg

http://vts.bc.ca/pics/milltest2.jpg

Next is a full depth cut of about .400" x .180" in one pass, normal cut at 2500 rpm with 9/16 4 flute end mill.

http://vts.bc.ca/pics/milltest3.jpg

Next is finish cut on same piece, .405" x .030 deep, climb cut.

http://vts.bc.ca/pics/milltest4.jpg

EDMTech
09-23-2006, 08:06 PM
Nice finish, looks like that will be a very capable machine.

What size servo/steppers are you using on it, and will they be belt driven or direct coupled?

Evan
09-23-2006, 08:12 PM
280 oz steppers, belt driven with a 2 to 1 ratio.

japcas
09-23-2006, 09:26 PM
Good work Evan. Glad to see you got it running even if it is just manual right now. Keep us posted as you get it going. Question, do you have any projects in mind yet to show off it's cnc capabilities or is that too far off to even think about yet?

Evan
09-23-2006, 10:01 PM
I have a few ideas. It won't be a lot longer, a year or two and I will be shutting down my store. The computer business is becoming a commodity business with prices so low that money can only be made with high volume sales. I foresaw this when I opened my business almost 9 years ago and had planned to shut it down in about 10 or 11 years which is right on schedule.

I intend to make a variety of astronomical accessories and possibly instruments and have a blast traveling to star parties during the summer to sell them. A lot of trade is done at star parties and we have some good ones in western Canada. There are some very well heeled people in astronomy that have no idea how to build anything but want something other than the run of the mill stuff.

As an example a fellow in this business in Texas built an eight inch telescope in his spare time when not filling orders. It was all hand polished titanium and beautiful. Not really functional as he left it all highly polished but a really nice piece of living room art. With some anodizing it would be an excellent performer too. He sold it to a guy in Holland for $25,000.

nheng
09-23-2006, 10:58 PM
Evan, Nice job and the cuts look quite good also. What did you use for the vertical slide method?

I just bought some 1/4" F1 felt from McMasters for my lathe wipers but have been having second thoughts about felt after recent readings. The original wipers had some kind of molded polymer (mid '70s vintage) scraper followed by felt.

Looking at your linear slides, they remind me of hydraulic cylinders in action. Any idea what they use to protect cylinders on heavy equipment? Maybe something of use there for you in the smaller sizes?

These look interesting: http://www.busakshamban.us/prod_global.htm?pid=354 and if you check out the left hand menu, there's a wide range of reciprocating seals.

Den

mochinist
09-23-2006, 11:11 PM
Sweet mill Evan, you do some very interesting stuff with just a lathe, it will be interesting to see what you turn out with a cnc capable mill.:cool:

Evan
09-23-2006, 11:13 PM
I'm not quite sure what you mean by "vertical slide". If you mean the Z axis ways then they are the same as the rest. All are 1 1/4" precision ground 1040 steel.

At this point I plan to use felts on the bearings as any other sort of seal would require disassembly to clean and reinstall. With felt they can be split rings that are easy to install and remove for cleaning. I have lots of machine felt and have already cut all the felt rings I need. I was waiting until I had the mill to this stage so I can use it to make the remainder of the minor parts it needs including the felt retainers.

tryp
09-23-2006, 11:58 PM
Looking good Evan! That is a nice finish, a rigid machine. I was more than impressed when I saw it in person. Your workmanship and care in the smallest of details have inspired me.

Have you gotten a new spindle motor controller for it, I'd assume so by the looks of those cuts?

I also like your future business plans, low volume, ultra high craftmanship specialty products in a field you love.

Erik

Evan
09-24-2006, 12:22 AM
Erik,

No, same controller that you saw with the same hum problems. I just was running it between the critical rpms where it resonates.

What Erik is referring to is what I showed him when he dropped in a few weeks ago. The motor has a very serious hum problem due to the cheap SCR controller. At certain RPMs it resonates badly and it telegraphs to the spindle. You can hear the hum beat with the spindle rotation.

The motor itself is just fine and has plenty of power. I intend to build a proper pulse width modulated high frequency controller for it but not until after I have everything else done. I plan on using closed loop feedback from an encoder on the motor so it will have maximum torque at all rpms.

Dan Craig
09-24-2006, 01:27 AM
lol
"...but want something other than the run of the mill stuff."

no pun intended...

Seriously, that mill is looking good, and the test cuts look good too. I'm looking forward to seeing the CNC upgrade complete - and some of the parts created.

John Stevenson
09-24-2006, 05:54 AM
Evan,

What controllers are you going to use ? at 280 oz / in I recon you are running about 2.5A per phase?

Evan
09-24-2006, 09:33 AM
John,

I'm using the Xylotex controllers. I have modified them by removing the weak little heat sinks and the adhesive heat sink tape and mounting some much larger sinks with arctic silver. Heat sink tape has very poor thermal transfer. This will allow me to run them at very close to the maximum safely. I'll be running them at about 30 volts. This will give a peak current of 60 amps per phase. The motors are rated at 4.6 amps at 2.2 volts. I'll be able to run the controller over the maximum 2.5 amps average as that is limited by the heat sinks in the original spec. I should be able to adjust them to an average of at least 4 amps with the new sinks and forced air cooling.

A.K. Boomer
09-24-2006, 11:04 AM
Evan, I must say that is impressive, youv built this entire mill? what is the base steel? are your linear slides plain bearing or ball? Is there an advantage to this over a dove tail? what about adjustability? did you bolt it together and pin? (meaning all the base plates and stuff) That mill is one of a kind for sure and it actually makes a regular mill look a little crude in some ways but solid pieces of cast iron are tough to beat for rigidity as compaired to just about anything else esp. when talking multi-peice units that are bolted together( Im told thats why its nicknamed "the dead metal" because it doesnt like to move around much) Are you concerned with fretting between bolted pieces or any kind of squirming at all?
Sorry for all the questions but your mill is amazing to me and its quite obvious that you are a pretty damn good engineer so dont think im picking on you, its just some of the stuff that i would have had to ask others because I would not be as sure of myself in said concerns, last but not least, if you dont own a mill then how did you build this machine?, if you tell me you did this on your lathe you are going to be an extemely dangerous person when you get this thing up and running esp. with CNC capabilities... nice work bro...

A.K. Boomer
09-24-2006, 11:20 AM
And yet one more question, what are you going to use to cover up those leads screws? Im wondering if you can use a "spiral" material like what is used on the newer haas CNC mills, its that thin spring steel that just keeps wrapping around the leads and keeps its shape and takes up almost no room when fully compressed but also will expand and cover leads nicely at full extension.

JRouche
09-24-2006, 11:52 AM
Looks good Evan. Chips look a bit like dust, speed yer feed :D

I imagine once you hook up the motors you will be able to adjust your feeds properly. JRouche

Evan
09-24-2006, 12:41 PM
Those chips aren't all from those cuts. :) When I crank it up to 5000 rpm it goes through the aluminum like routing wood. :D I just need to fix the motor 60hz hum problem.


Are you concerned with fretting between bolted pieces or any kind of squirming at all?

Uh, no. Have you tried counting just the fasteners you can see? :D

It's built like an airplane and yes, I did use only my SB9 to build it, not counting band saw and drill press. I couldn't have built it from steel using those tools. Besides, I like aluminum. As for dampening, the multi-part and multi layer contruction provides a lot of dampening as does the careful attention to selecting non-resonant dimensions for most parts.

wierdscience
09-24-2006, 04:37 PM
Looking good,is that a Chiwan Tin coated endmill in the pics? If it is,and the mill is finishing that good,it is an achievement.If you like the finish now,wait til you get hold of some OSG endmills,they are adictive:D

BTW,are you going to make your RT a fourth axis?

Evan
09-24-2006, 04:49 PM
Yes, that is an el-cheapo end mill. Yes, the rotary table is going to be a 4th axis. I have the motor and driver for it. And yes, I need to buy some quality end mills.

motorworks
09-24-2006, 07:11 PM
Evan
What software do you plan to run this with?
Turbocnc or Mach3?
As for endmills, I found that HSS(best price to work output) worked best on my BP-Boss.
take care
eddie

HTRN
09-24-2006, 07:53 PM
Those chips aren't all from those cuts. :) When I crank it up to 5000 rpm it goes through the aluminum like routing wood. :D I just need to fix the motor 60hz hum problem.

You should see a VMC buzz through Aluminum at 7000+, it even sounds like a router cutting wood. Only time a ran a cutter down at 5000 in Aluminum, it was with 3" face mills.:D


HTRN

TECHSHOP
09-24-2006, 08:10 PM
As usual you design and machine work is outstanding!

(Tried to type more the first 3 times but having 'puter issues today).

BillH
09-24-2006, 08:54 PM
what techshop said and I dont consider myself an ass kisser.

Evan
09-24-2006, 09:13 PM
The plan now is to run Turbo CNC on an IBM Thinkpad. I have two identical ones so I have a backup. Computers aren't really a problem, I have to try and find places to put them.

abn
09-24-2006, 09:48 PM
Awesome work, Pics, and documentation...

mochinist
09-24-2006, 10:41 PM
The plan now is to run Turbo CNC on an IBM Thinkpad. I have two identical ones so I have a backup. Computers aren't really a problem, I have to try and find places to put them.You gonna use fingercam or are you planning on getting a actual cam package?

Evan
09-24-2006, 11:09 PM
Fingercam to start. I'm used to that sort of thing.

S_J_H
09-25-2006, 12:06 AM
Evan, I am very impressed with your mill. It was a lot of work just to cnc my x3. I can only imagine how much time and thought went into your machine!
I have to hand it to you guys that have the motivation to build a mill from scratch!!
Steve

Your Old Dog
09-25-2006, 09:47 AM
Gee Evan, I could have saved you a lot of time. Harbor Freights got these cheap..................... :D

What everyone else is saying of course, pretty damn impressive.

smagovic
09-25-2006, 06:29 PM
Evan, I am so glad the suspense is over. I was hearing for some time now that you are building a mill, and could not find any pictures of it anywhere. Now, you pulled the curtain off. It is a very interesting looking machine. I can tell that you have put a lot of thought and work into it (and aluminum too). You cannot hide the fact that you love to work with Al. What is the length of the X and Y axis? Obviously the Z axis is build like a rock of Gibraltar. It looks very solid. I was wondering a bit about the X axis, if that one would not whip a bit under the pressure. I think you did as best as one can with just a SB9, obviously dovetail bed was pretty much out of the question (then again, knowing you, I would not be surprised if you come the next week with a picture of a brand new dovetail bed made on your SB9 and prove me wrong). But, once you will have the mill in full production it can be used to recreated itself, to improve itself, if necessary. Some people have all the fun! Good luck with the rest of it, and please keep us posted. Many thanks. Vic

Evan
09-25-2006, 06:58 PM
The X axis has an additional constraint that isn't easy to see. At the back end of the Y axis table underneath is a full width rail of 3/4 x 3/4" CRS fastened to the base in a manner that allows for temeperature change. The Y table is completely constrained in rotation about the X axis by this guide mechanism which has a cast iron adjustable gib plate under the rail and a teflon slider on the underside of the Y table above the rail. Adjustment of the cast iron gib is from above in the back end of the Y table between the ways and is very easy. This makes the entire system rock solid without overconstraining the motion.

http://vts.bc.ca/pics/millxaxis1.jpg

The envelope is X 12.75", Y 9" and Z 12"

smagovic
09-26-2006, 05:19 AM
Evan, thanks for the explanation. As I said before one can tell you have put a lot of thought into the design of your mill.
I hope your ear situation will improve soon. It is not fun to be getting old. I am bit more down the road from you in this regard and have problems. It seems that regardless of all the electronic gatgetry which is now available to diagnose things, it is still very difficult to pinpoint what is wrong. I think part of it is information overload. Hopefully, once they will know for sure what is wrong they can treat it without creating side effect problems. Take care. Vic