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John Stevenson
12-21-2012, 06:49 PM
Got this standard Bridgy POS here and it's getting tiring winding the knee up and down.
I know you can get these Align units to fit but quite expensive here 350 or around $550 plus 110 volt so need to run a transformer.

Also read a bit about them being weak on the gearing.

I have shed loads of 3 phase geared motors and it would be easy for me to fit one on and run it thru an inverter which I have in a small size.

Problem being there is no easy way to keep manual feed due to the worm drive box and a dog clutch setup starts to get big and messy. My take on it is that I don't need blinding speed and if the gearing is chosen to run at a reasonable rate then the inverter will allow an absolute crawl.

So my question to the unwashed is "If you have a knee power feed do you use the manual at all or just rely on power ?"

Toolguy
12-21-2012, 06:58 PM
Personally I would not want to do without the manual option for fine positioning. What I did was to use an 18V cordless drill if a lot of cranking was needed. I could go up and down several times on one battery charge. You just use an adapter (easy to make) for the drill motor and use it or the crank handle interchangeably.

lane
12-21-2012, 07:11 PM
I use rapid up and down ,under power and a manual feed handle to set and advance the knee for depth of cut . The knee hand feed is used for all cut depth setting.

browne92
12-21-2012, 07:13 PM
So my question to the unwashed is "If you have a knee power feed do you use the manual at all or just rely on power ?"

Oh, so we're the unwashed now, huh? I'll have you know I take a bath once a week whether I need it or not. :p

Weston Bye
12-21-2012, 07:13 PM
Was I to do such, I think I would employ some sort of differential gearing plan with a couple of brakes. Lock the hand crank and run the motor for power feed. Lock the motor to use the hand crank.

.......probably too much trouble to build, but would work slick when done.

hareng
12-21-2012, 07:14 PM
Going back a bit when used one but no way could i live without the manual cranking.
If you can keep that as well, go ahead.

Weston Bye
12-21-2012, 07:21 PM
Another (harebrained?) idea. Leave the top of the jackscrew alone, but replace the nut support tower with the motor and gearbox turning the nut. As long as the motor is not too strong, you can keep the screw from turning by just holding the hand crank while jogging the motor with the other hand.

Visions of Sir John being beaten about the kneecaps and nads by his POS Bridgeport (revenge!)

aboard_epsilon
12-21-2012, 07:34 PM
someone somewhere posted something about making an adaptor for a battery powered drill ..and just doing it that way

if you don't fancy battery power you could have air nut driverwith same adaptor on it hanging down on a springy air hose that reels up out of the way

all the best.markj

Punkinhead
12-21-2012, 07:40 PM
Don't listen to this talk about fine Z adjustments on your POS Bridgeport. If you need an extra 0.010" depth of cut just use a dull cutter and increase the feed rate until it flexes enough to dig in that extra 0.010".

You're welcome.

John Stevenson
12-21-2012, 07:43 PM
OK, Like Weston's idea, never thought about that and that's the reason to throw ideas out. Could always have a plunger that locked the horizontal shaft and only disengage it when needing manual but I'm sure I could manage with just power.

Bear in mind the motors and gearboxes I have in mind are streets in front of an Align unit.

However couple of things, one is I only use the knee for rough positioning and use the quill for putting cuts on as I have a digital display on the quill, machine is imperial but I work 95% metric.

Handle on the knee is fixed permanent in that it has a large washer and screw holding it from coming completely off, got smacked in the nose a while ago winding like crazy and it spun off so this makes the drill arrangement tedious plus I want a complete job, everything machine mounted

lakeside53
12-21-2012, 08:06 PM
I have a Servo 140 (150, I can't remember) unit on my BP knee. it gets used every day, BUT, the last few thou or for "fine" adjustment is always by the handwheel.

Toolguy
12-21-2012, 08:36 PM
OK - now that we have the full story it's back to the drawing board for a redesign!:rolleyes:
In that case, an easy fix would be to replace the hand crank with a gear motor, the motor hanging vertical off the left side. A momentary switch in a convenient location would polish it off. That would make an easy install and maintenance with the motor pretty much out of the way.
Edit to add - You could hold the gear motor on with the bolt and washer already there and appropriate spacers on the drive shaft.

Don Young
12-21-2012, 08:43 PM
A vee belt and pulley system could give you a drive with easy de-clutch capability.

lakeside53
12-21-2012, 08:48 PM
Actually... experiment with the vfd "jog" function. With gearing it might be able to be set so that it say 1/2 thou per hit, or even a 10th or so if you gear low enough ;)

Forrest Addy
12-21-2012, 11:57 PM
If you just want traverse up and down without feeds consider this:

http://www.ebay.com/itm/NEW-STEEL-GEAR-SHAFT-CLUTCH-INSERT-FOR-BRIDGEPORT-MILL-1230-/370391645673?pt=LH_DefaultDomain_0&hash=item563d0ffde9

This gadget engages the knee face clutch. Add a machined piece that slps over the pilot diameter arrenged with an extended flatted shaft so you can drive it with a 1/2 V/S drill. Dedicate the drill to this service so whenever you need to position the knee you grab the drill and buzz it to whatever height you need. Maybe if the drill is sensitive enough you can use it for power feed but it would be awkward.

I saw a flurry of such gadgets in the last year or so but I could find no references.

Next step is buy a Servo syle knee feed unit. I have one but it's slow.

flylo
12-22-2012, 12:48 AM
I bought 3 of those adapters for a cordless drill for 3 for $30 + $5 shipping, cant make then any cheaper * they fit every mill I've tried. They make steel * alum, I got the black steel ones & love em.

goodscrap
12-22-2012, 05:06 AM
A couple of random ideas without much scrutiny,

Put a thrust bearing Under the nut and spin that with a motor, or even a thrust bearing under the pedestal and spin the whole pedestal withe a base mounted motor. you'd want some sort of dro scale though as there would be no way to measure the movement. Similar ideas to western

Or

Use a modern starter motor off a car, you could probably get one in the knee direct acting on the cross shaft, it would be dis-engaged normally so you can hand crank, but engaged when the solonoid powered up and motor running. I don't know how familular you are modern starters but they often have a reduction gear set in the nose - you may need to find someone who knows about motors ;) to see if you could swap it for one of a more suitable voltage, unless you have a high output 12v source to hand. If the gearing is off then you could just use the starter nose and have a jackshaft via tooth belt drive to gear it down and remote mount a different motor on the other side of the knee. Prob needs to be a dc motor so you have reverse


Brian

John R
12-22-2012, 10:06 AM
I made a socket with a roll pin in it to engage the sprocket on the shaft and drive it with a drill motor

John Stevenson
12-22-2012, 10:39 AM
Weston's idea, which I really like won't work as the top of the nut column goes up inside the knee casting when lowered down, bummer,

Drill motor is definitely out, it has to be part of the machine and available at a seconds notice on a switch.

Easiest for me to try is hanging a geared motor on the shaft and driving the dog clutch with a temporary pin and wire it up to an invertor.
Proof of the pudding etc and if it's not suitable, nothing lost.

sdeering
12-22-2012, 11:12 AM
I've also hear guys adding an air cylinder under the knee to take most of the weight off the nut, then add a stepper. This might take enough weight off the original system that you can put a shorter crank on the mill and move the knee faster by hand and keep your chiclets in your mouth or use a smaller motor in place of the crank. Ive been pondering doing this the my series one CNC.
Stephen

goodscrap
12-22-2012, 12:59 PM
Weston's idea, which I really like won't work as the top of the nut column goes up inside the knee casting when lowered down, bummer, .

what about spinning the whole pedestal and nut, could have a chain drive, worm and wheel or whatever suits you mounted on the base of the machine, yes you'd need to do a bit of work on bearing mechanism and some means of keeping the chips out

Brian

1-800miner
12-22-2012, 01:06 PM
John, scroll down a few threads to Brian's mechanical clutch.

Weston Bye
12-22-2012, 01:31 PM
Weston's idea, which I really like won't work as the top of the nut column goes up inside the knee casting when lowered down, bummer,...


I laid awake for a while last night wondering about that.

My thoughts are to remove the pedestal and fab up a long hollow tube to carry the nut. The tube would be fitted to a hollow-bore right angle reducer. (I presume that you have one waiting around for the right application, also presuming that the gearbox has the bearings sufficient to handle the weight of the knee) The reducer is then fitted to a match plate that bolts to the Bridgy base in place of the pedestal.

914Wilhelm
12-22-2012, 01:53 PM
I just used the cheapest CDCOtools.com knee motor and did a little modification so I could use the handle either on or off it. Only took a few times to remember to remove the handle when i was using the motor. The handle can really wack you hard.

http://i972.photobucket.com/albums/ae201/914wilhelm/KneeDrive_zps4c589028.jpg

http://i972.photobucket.com/albums/ae201/914wilhelm/KneeHandle_zps4106c828.jpg

bborr01
12-22-2012, 02:42 PM
Hi John,

I am wondering why you are so against the drill idea. I am using a 1/2" DeWalt 18 volt drill with an adapter and it works GREAT. I had a job that ran about 175 hours to complete and most of the work was on the Bport and Kent mills. The adapter and drill setup saved me not only VERY CONSIDERABLE time but also a lot of wear and tear on my arm. I usually just leave the setup hang there in place of the crank until I need the crank for fine adjustment to the knee. Up or down with the flip of a switch.

I also made an adapter with a 3/4" socket on it that I use for rapid open and close of the vise and it also works fine for the Y axis. Just put it on the nut and let it rip. I always soft start the drill when running it in reverse on the Y axis so it doesn't unscrew the nut, which hasn't happened yet.

I was going to post a couple of pics but due to photobucket suckage here too I wasn't able.

Brian

edit: it also passes the KISS test.

Highpower
12-22-2012, 03:27 PM
I just used the cheapest CDCOtools.com knee motor and did a little modification so I could use the handle either on or off it. Only took a few times to remember to remove the handle when i was using the motor. The handle can really wack you hard.

http://i972.photobucket.com/albums/ae201/914wilhelm/KneeDrive_zps4c589028.jpg



I just bought a similar Z power feed, but it came with an extension shaft that is drilled and tapped on the end to retain the crank handle behind a spring to keep it disengaged until you want to manually crank the knee.

http://img.photobucket.com/albums/v82/Highpwr/Temp/Knee_Extension_Shaft.jpg

But I also recently ordered an 8" cast iron hand wheel to use instead of the factory crank handle. I'll just need to mill the lugs into the back of the hub on the hand wheel to make it work. Shouldn't need the huge crank to make fine adjustments by hand. At least that's the plan.... ;)

Boostinjdm
12-22-2012, 03:32 PM
I've been working on installing my new Servo Dynamo on the knee. Very smooth and plenty of power even if you snug up the locks. I'm trying to order a safety ball crank like my x axis has now. The servo dynamo was reasonable at $422 to my door.

EVguru
12-22-2012, 06:10 PM
I only use the knee for rough positioning and use the quill for putting cuts on as I have a digital display on the quill, machine is imperial but I work 95% metric.

My metalwork teacher would have given you a clip round the back of the head for abusing the machine :D

'The quill is only for boring and drilling operations and should be retracted and locked whenever possible'

I've had an Align drive on the X axis for quite a while with no problems. It came off the clearance table at Cronos for 50 and the only thing wrong with it was the operating lever roll pin not being in the micro-switch rocker slot. I snagged another unit off the clearance to put on the knee, but I've not got around to diagnosing any problems and fitting it. There's a spare moulded plastic gear in the bottom of the unit and replacements are quite cheap from the US.

J.Ramsey
12-22-2012, 06:16 PM
I went the CDCO route about 7 years ago, no problems so far.
http://imageshack.us/a/img62/3912/zpowerfeed.jpg

I had to make new clutch/couplers as the tooth count and size were different from the original and while at it I made a new handle that doesn't bite my leg when walking by and added a 10" handwheel from Enco.
http://imageshack.us/a/img15/5554/zhandles.jpg

lakeside53
12-22-2012, 08:04 PM
You need to use that mill. Damn, my table hasn't looked like that since it left the factory ;)

lakeside53
12-22-2012, 08:06 PM
'The quill is only for boring and drilling operations and should be retracted and locked whenever possible'
.



LOL.. tell that to my 3 axis cnc'd BP! never locked... Always in motion.

Highpower
12-23-2012, 10:44 AM
I went the CDCO route about 7 years ago, no problems so far.
http://imageshack.us/a/img62/3912/zpowerfeed.jpg

I had to make new clutch/couplers as the tooth count and size were different from the original and while at it I made a new handle that doesn't bite my leg when walking by and added a 10" handwheel from Enco.

Did the clutch/shaft extension fit the original main shaft in your machine, or did you have to modify/make a new main shaft for it?
I haven't torn mine apart yet, but I have a feeling the extension shaft I got has a larger thread size than what is on my machine now.
Will have to wait until after Christmas.... ;)

Richard King
12-23-2012, 11:19 AM
When I was rebuilding a Bridgeport a week and scraping it. I check the knee by sitting a blade square in the top of the knee and I got tired real fast cranking up the knee. So I made an adapter and used a reversible 1/2 " electric drill motor. Was sweet :-)

J.Ramsey
12-23-2012, 11:21 AM
My mill is a '02 grizzly 9x49 and everything was direct fit IIRC.

The instructions say to drill thru the adapter and use the supplied roll pin,I tapped the hole and put a set screw in instead.

Highpower
12-23-2012, 12:09 PM
Copy that. Thanks for the reply.

goodscrap
12-23-2012, 06:20 PM
going back to the original question, i had another thought of putting the motor in the knee, driving via a toothed belt, onto the original shaft. you then need a double freewheel mechanism to allow the hand crank shaft to be un-hindered, but when the motor drive kicks in it locks onto the shaft and transmits drive, in either direction. originally i was thinking along the lines of sprag clutches, but they're one direction....

double direction freewheel mechanisms do exist, but all the ones i can find images on have the outside shaft as being the freewheel part and the centre shaft as being powered, somehow this needs flipping inside out to be useful to you.

John Stevenson
12-23-2012, 08:12 PM
Looking at this logically.
A standard 3 ~ motor here on 50 Hz runs at 1425 rpm push that thru a 40:1 reduction box and we get a top speed of 35.63 still at 50 Hz.

Now an inverter will go down to 10 or 12 Hz and still have some guts, so say 10 HZ and this gives a top cranking speed of 7.125 revs per minute

Using a 60:1 reduction gives from 23 revs down to 4.75 but if I over speed the motor I can get it up to about 42 revs

So if we say 5 revs low speed that's 12 seconds to do one rev and I'm positive that it's possible to stop at any given point, failing that i can always fit a handwheel with folding handle on the end of the motor to get into position.

In fact thinking about this the CNC has a powered knee that's only one fixed speed and relies on the handwheel to get the final size, at least I'll have variable speed