PDA

View Full Version : ACME thread



Smokedaddy
02-17-2005, 07:30 PM
Need some help. Oh, BTW, I'm not a machinist either. Didn't say I was stupid, just not a machinist. <grin> I have a Craftsman model #2486 8" rotary table I got off of eBay a few months ago. The one that has the 3 handles on it ..... X, Y and the rotation one. It looks like it's a new as can be. I took it apart and cleaned everything up but one of the handwheels isn't as smooth as I'd like it to be.

To make a long story short ...... it appears one of the ACME threaded rods is ever so slightly bend, maybe like .0015" ths. They probably dropped the puppy from a short height or something. I put the shaft on a granite plate as was able to slide a feeler gage under it, so that's where I arrived at the dimension. I also noticed one of the threads is buggered up near the end of the shaft.

See image here: http://www.pbase.com/smokedaddy/image/39878475

Anywho ... how would you suggest fixing it?

Thanks,
-SD:

precisionworks
02-17-2005, 07:53 PM
Nice photo, SD. A 2" scotchhbrite surface conditioning disc, coarse or medium, on an air angle grider will smooth up that little nick.

If you have access to an arbor press (like a 3 ton) you can support the ends of the shaft on wood blocking and press on the high point of the bend (also wood padded). No science here, just go slow and check on the surface plate till it rolls straight.

------------------
Barry Milton

JCD
02-17-2005, 08:06 PM
You might try a file on the damaged thread. Just blend the contour of the thread.

JCD

Mike Burdick
02-17-2005, 08:18 PM
<font face="Verdana, Arial" size="2">Originally posted by Smokedaddy:
...To make a long story short ...... it appears one of the ACME threaded rods is ever so slightly bend, maybe like .0015" ths.
</font>

0.0015" shouldn't cause a problem at all! Seems to me the messed up threads are the main problem and when you get that fixed everything should work okay.

lenord
02-17-2005, 08:26 PM
In case you don't already know this:

You can get acme threaded rod in short from Enco. It's cheap too.

FWIW
Lenord

Smokedaddy
02-17-2005, 09:12 PM
Dunno, thanks for the tips. I think the puppy wasn't alligned bored, right on either. I know when I assembled it once, that the ACME rod didn't fit precisely in the bore in the cast, like it should. Proly that and the bent shaft are creating the damn problem. I suppose that's why I got such a good deal'eo on it via eBay. Should of bought the new H/V Bison I was looking at on KBC.

Cheers,
-SD:

ltvTOM
02-17-2005, 10:40 PM
I have a scanned instruction and part list for the Craftsman model #2486 8" rotary table in a PDF file.You can download it here:
http://s11.yousendit.com/d.aspx?id=2QJ41RCPO68831Q8R3LD3HJ0DU
(it's about 1.2 meg)
It will only be there for seven days.
Tom

happy02
02-18-2005, 08:40 AM
I agree that the thread burrs are causing the problem. I would file them to clean up, reassemble and try. If the slight bend still causes a problem then I would attempt to straighten it. If worse came to worse, it would not be too much of a chore to make a new one from scratch. Good luck, just my 2cents...Joe

charlie coghill
02-18-2005, 09:53 PM
I would agree with Happy