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View Full Version : Crossfeed drive done, almost



Evan
10-13-2003, 05:44 PM
Thanks again to Wes, the electromagnetic clutch works perfectly. This was a smooth project. I had all the right parts and it all fell together. I still have to do some wiring and make a cover to keep the chips out of the gears.

The number one consideration for this project is that there be no modifications to the lathe. That is achieved.

The brass fitting is threaded on the end of the crossfeed leadscrew. Left hand Acme thread, inside, blind. That was the hardest part. I had to make it twice. Then we have a very special zero backlash helical coupler. $$$. Was free though. Dug it out of the packrat stash. Next is the black clutch. It works perfectly and gives the instant on/off that I wanted. It will slip at just the point where you would say to yourself "Ugg, why is this so hard to turn?"

It is powered by the motor from a barbeque rotisserie. It gives a rate of .005 per second which should be perfect. It can be slowed to about half that speed using a dimmer although it is a synchronous motor and is not designed to be speed controlled, but it works great.

All in all, a nice project.


Forgot to mention, it removes by unscrewing two bolts. Takes about 30 seconds.


http://vts.bc.ca/img/cfd1.jpg



[This message has been edited by Evan (edited 10-13-2003).]

Joel
10-13-2003, 06:01 PM
Nice Evan! Consider rigging a hand wheel for convenience.

Weston Bye
10-13-2003, 06:18 PM
What an elegant installation! On the backside of the lathe, out of the way, the original handwheel still accessable on the front. Beautiful.

Wes

shaque
10-13-2003, 09:42 PM
Well, maybe I won't get rid of my 9SB now, cause that was the weak link, not having powered cross feed...got to look at that now. Thanks Evan.
Jim http://bbs.homeshopmachinist.net//smile.gif

shaque
10-13-2003, 09:49 PM
waitaminute
what did I miss here? whats this about a electromagnetic clutch? fill me in please
jim

wierdscience
10-13-2003, 09:58 PM
Mag clutch to decouple the power feed drive,very nice,I like.

Come to think,our big lathe is like that at work,all the feeds are droppped in by mag clutch,just a switch on the console,many practicle uses in the shop.

Nice job!

Evan
10-13-2003, 10:48 PM
Jim,

The black round object at the right is a magnetic clutch. The barbeque motor drives the gear visible on the left side of the clutch. When energised with 24 volts the clutch instantly drives the crossfeed leadscrew. When power is removed from the clutch it stops instantly. When power is removed from the clutch there is no additional load on the leadscrew and the crossfeed works completely normally. I will wire the barbeque drive motor to the lathe motor so that it is on whenever the lathe is running. This gives me power crossfeed at the flick of a switch. The unit is bolted to existing threaded holes that are meant for a taper turning attachment. It limits the crossfeed travel by only 3/8", not a problem.

shaque
10-14-2003, 08:01 AM
Gotcha! http://bbs.homeshopmachinist.net//biggrin.gif
Now tell me where these are available.
Thanks
jim http://bbs.homeshopmachinist.net//smile.gif
PS, I think you are going to have to do an article on this, or at least show some pics of how you done it, as I'm sure there are a few SB9 owners out there just lurking on this post and would like to do this to thier machines...
JS

Evan
10-14-2003, 11:44 AM
Jim,

I'll take a few more pics showing the device. It's not complicated. Electromagnetic clutches are widely used in photocopiers. There are several types and most operate on 24VDC. Since this drive is only designed to run in one direction the wrap spring style of clutch will work also, as long as it is in the right direction. The clutch I used is not a wrap spring clutch, it is a magnetic multi pressure plate type.

You should be able to go to any large photocopier dealer with a repair facility and find something that will work, probably for free. If you know a copier service tech ask her/him. They are changed out because they start to slip but will still work well enough for this application. They are also often changed because the internal back emf diode has failed. That would have no effect when switched with a toggle switch.

wierdscience
10-14-2003, 08:53 PM
C&H sales,Herbach&Rademan and a few other surplus co.s

Even small a/c clutches from automobiles will work

Evan
10-14-2003, 10:33 PM
Here are a couple more pics. It isn't that hard to make. All kinds of similar but different approaches would work. The one item that would have to be the same is the brass coupler to the leadscrew. It must allow for the cross slide casting to clear over it. I made it so that it engages at least three turns of leadscrew thread. It doesn't need a setscrew as it is tightened by the drive.

The barbeque motor has a square drive socket so I hand ground a shaft to a square end until it was a light press fit. I like the clutch but other engaging mechanisms could easily be used.

http://vts.bc.ca/img/cfd2.jpg

http://vts.bc.ca/img/cfd3.jpg

charlie coghill
10-14-2003, 10:50 PM
That is a great project. With a little thinking that could be addapted to the X and Y feeds on a BP type of mill.

HSM, I believe it was, had an artical on doing the above. I started aquiring the material to build it but have not gotten around to it yet. This will give some boost to getting that done.
Thanks.
Charlie