# Acme Rods In 101.28990



## roadie33 (Mar 7, 2015)

Can someone tell me what size the Acme rods are in the Compound and Cross slide on a Craftsman Commercial 101.28990?


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## Rob (Mar 8, 2015)

On the older 12" they are 1/2" 10 tpi left hand threads.  I believe they are all the same.


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## roadie33 (Mar 8, 2015)

Thanks Rob. I looked thru all my literature and couldn't find the info.


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## roadie33 (Mar 8, 2015)

Those are just 1 start threads, right?


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## Rob (Mar 9, 2015)

Yes.


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## wa5cab (Mar 9, 2015)

I don't have any length information but the unthreaded portion is .375" dia. and the threaded end is 3/8"-24 UNF/


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## roadie33 (Mar 9, 2015)

I want to try to make one out of 1018 CRS to see if it works.
I just can't see paying over $100 for a new Cross Feed screw.
I see plenty of them used on Ebay, but don't want to get one that might be too used.
They can't be that hard to make.


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## hdskip (Mar 9, 2015)

McMaster-Carr has 1/2-10 Acme precision rods. Both left hand and right hand offered. $6.53 per foot in #' and  6" lengths.


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## roadie33 (Mar 27, 2015)

Where can I find the specs for the Acme screws in the Compound and Cross slide?
Mine have a lot of backlash and need to replace them.
Bought some left hand 1/2 x 10 precision rod from McMaster, now I need to know the specs.
I really don't want to tear mine apart then put it back together twice.


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## Rob (Mar 28, 2015)

Not sure if you could call and get the specs from Atlas (Clausing) or not.  I don't think that you would need precision Acme thread in the compound and cross slide.  The only place that I would think it was needed is the lead screw and that would be for thread cutting but again not sure if it would be needed there also.


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## roadie33 (Mar 28, 2015)

It was cheap, and I wanted it to be good and straight.
Now I just need the specs on them.
I doubt Atlas would give them out since they would rather sell me new ones.


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## wa5cab (Mar 31, 2015)

Mike,

I concur that it wouldn't pay to call and ask Clausing for the drawing or the dimensions.  However, aside from the few minutes that it takes to readjust the end float, there is really not much to pulling the cross feed screw.  If you don't have the PDF copy of the 101.28990 manual, let me know, send me your email address, and I'll send it to you (I hope that we get Downloads running again soon).


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## master53yoda (Apr 1, 2015)

roadie33 said:


> Where can I find the specs for the Acme screws in the Compound and Cross slide?
> Mine have a lot of backlash and need to replace them.
> Bought some left hand 1/2 x 10 precision rod from McMaster, now I need to know the specs.
> I really don't want to tear mine apart then put it back together twice.



Just a question,  the rods are steel and the nut that they go through is brass,  most of the time the wear is in the nut not the rod.  the way to tell is if the back lash is different at the ends of the travel then the middle where the most use is.  I use DROs on my lathe and mill and that eliminates the backlash problem because the dro tells you where the cutter really is.  you could have .125 back lash and it wouldn't make any difference when useing a DRO.  The dros for my lathe cost about 125.00 for a 36" and a 12". 

Art B


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## roadie33 (Apr 1, 2015)

I replaced the brass nut already and still have backlash. About a quarter turn. I want to replace the rod before it tears up the new nut anymore.
I have the PDF file but it doesn't give any specs and the drawing leaves a lot to be desired on tear down and replacement info.
I guess I'll just have to take it apart and mic the shafts and write down dimensions. Then put it back together and hope I don't miss anything. 
I don't want to be doing this more than 2 times.


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## chips&more (Apr 1, 2015)

You really do not need the specs. You have everything right there. You can tear down one translation at a time. Example; take apart the compound removing its feed screw and then put it back together without the feed screw and tighten the gibbs a bit so it does not move. Now you have the example to machine the new feed screw on your lathe. Then install the new compound feed screw, set the compound at 90°, remove the cross feed screw, you get the picture…Good Luck, Dave.


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## wa5cab (Apr 1, 2015)

Dave,

Not without taking both apart.  Although both the Acme and the UNF threads are the same diameter and pitch on the two screws, the cross feed screw is quite a bit longer.  And it has two Woodruff key seats instead of one.  He needs the length information.

Mike,

Did you adjust the feed screw end float?  You do this by loosening the special nut holding the cranks on, turning the nut (actually a threaded shoulder bushing) between the crank and the bearing, and then tightening the special nut.  Usually takes several tries to get it near zero but not dragging.

I agree about the drawing.  For one thing, the tapped post on top of the crossfeed nut (33) is not nearly as large as drawn.  And the shim(s) (34) is rectangular, not circular, and the hole in it fits over the post.  The shims are, BTW, "as required".  My machine has none.  Also, the hole in the saddle for the cross feed screw bearing (31) is much larger than drawn.

It is clear from the drawing that to remove the screw (53) you remove (20). (29), and (23) through (27).  Both of (30) remain in (31).  But it is not clear and I didn't try it whether removing (31) from (50) allows you to extract (53)  with (24) and (32) by just pulling it out the front of the saddle.  Or whether you have to pull the screw out the rear, in which case there is no need to remove (31).  I actually removed (31) once but I only did it to confirm that the threads were right hand for someone who needed to remove theirs, was having a hard time of it, and wanted confirmation that the threads weren't left hand.  When you find out (if you find out) let us know.


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## roadie33 (Apr 2, 2015)

I adjusted just about everything there is to adjust trying to get the backlash out.  The end float is a pain to get just right. A soon as you think you have it and tighten the crank nut it's too tight so you back the nut back off, then the float bushing and back and forth till you get it snug but still able to crank it easy.
Still have about a quarter turn with no movement.
I believe the cause of the wear was the hard use of the milling attachment when I was making some extra QCTP Holders out of 12L14 plate. There was a lot of force on the screw when cross feeding while milling  5/8" wide x 1/8" to 3/16" deep slots for the tooling.

I agree with you that (33) is misleading in size. I don't have a (34) either. 
I tried to take it out last week and got all the way to unscrewing (31) with (30) thru (32) and it would not slide out.
I didn't try to hard as I didn't want to bend or break something important and not be able to do anything for need of replacement parts. I'll give it another try this weekend and see what happens.


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## wa5cab (Apr 3, 2015)

Yep, adjusting the end float is a PITA.  It may help a little bit if you run the carriage nut off the end of the screw before doing it.

And incidentally, my written steps for removing the screw should have begun with running the nut off of the screw and sliding the cross slide just a little farther.


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## Rob (Apr 11, 2015)

Here is a cross slide screw on ebay with a tape measure next to it.  It will give you some dimensions.

http://www.ebay.com/itm/ATLAS-CRAFT...485?pt=LH_DefaultDomain_0&hash=item43d90f54ed


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## roadie33 (Apr 11, 2015)

Thanks, I appreciate you finding that.
Will definitely come in handy.


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## Jimsehr (Apr 16, 2015)

You might google   EVANUT     it tells you how to make an actel nut that shrinks around your lead screw.
Thousands of people have checked it out. All most no backlash.
jimsehr


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## roadie33 (Apr 26, 2015)

What type of Bronze is the Cross slide nut made out of?

660, 924, 932 or 954


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## caveBob (Apr 26, 2015)

Ditto what Jimsehr above said...

I made a "hybrid" version for mine:













...and while you're at it, do something similar to tighten up the carriage nut bushings, what I did on this page...


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## Strtspdlx (Apr 27, 2015)

I doubt it helps any but to remove backlash on my 10" I took everything apart and run the nut to the part of the lead screw for compound and cross slide with the most movement. The. Took a torch to the nut till it was hot enough to reform to the threads in the screws. Now I have almost zero backlash and it's been that way for several months using it 2-4 hrs  a day. I was worried about ruining temper on the screws but they're already heavily worn. This was my cost effective solution to my problem. 


Regards-Carlo


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