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Help with compound assembly issue

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DiscoDan

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#1
Ever since I bought my Craftsman 12x36 at an auction I have had issues with the compound feed screw and handle assembly. I have the parts manual and it looks like I have all of the correct parts. The problem is that when I assemble it the parts to the outside of the face-plate want to keep threading toward the face-plate, which then sandwiches the face-plate between the outside assembly and the collar at the end of the acme screw and then the whole shebang won't turn. You can see that there are obvious wear marks on the face-plate from before my ownership so it looks like a long-standing issue.

I believe I have the "commercial" compound. I have considered buying a different version that looks like it has different hardware that may assemble better. They aren't too expensive on that auction site.

Thoughts?
 

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mickri

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#2
I just took mine apart. Two differences that I see in your pictures from my lathe. First the washer in my lathe is different. My washer is very thin, 0.0125 thickness, with a 3/8 id and a 7/8 od. The washer is not plastic and not metal. Don't know what it is made out of.

IMG_3635.JPG

Second the order of the parts on my lathe is different from your picture.

IMG_3636.JPG

On my lathe the assembly is the lead screw goes through the face plate. Then the thin washer goes on. Next you have the dial followed by the nut/sleeve that the slips into the dial as you screw it onto the lead screw. The nut/sleeve was not tight. As best as I can tell its purpose is to control the play between the lead screw, the face plate and the handle if that makes any sense. Next is the serrated lock washer, handle and nut. This nut was very tight. I had to use a socket to break it loose.
 

DiscoDan

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#3
mickri, that is interesting. Can you tell me what model lathe you have? I would like to see what your parts list shows as far as sequence of parts since the way you have yours laid out is different than mine. Specifically, the threaded nut (5th part from the right) is oriented backward from mine. If I assembled mine that way the numbered dial would no longer be next to the face-plate and would be on backward. And from my parts list the washer goes on the threaded nut against the collar portion of the nut.

FYI, my lathe is a 101.28940.

Never mind with the model number, I found the documentation and yours is exactly as it should be.
 
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DiscoDan

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#4
It seems like there should be a way to lock the whole assembly to the shaft so that it can't keep threading toward the face-plate but I don't see any way to do that.
 

BaronJ

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#5
Is there not a grub screw in the sixth part from the right like in Micks picture ?
 

DiscoDan

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#6
No, there is no grub screw in anything. In the parts guides for other versions of the Craftsman lathe it seems like there is, but not in mine.
 

BaronJ

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#7
Hi Dan,
I wonder ! Would adding a grub screw help ?

From what I can see that threaded bit sets the clearance between the two faces and once set shouldn't move.
 

pdentrem

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#8
I was thinking that the shouldered bushing is or should be just a little longer than the dial and that washer is there to as a thrust washer?
 

markba633csi

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#9
There are two versions of this thing. One has the thumbscrew dial and the other (101.28940 for example) has the knurled ring arrangement. If you check the manual for the latter there is a factory procedure for setting the preload on the dial, but it is touchy. Clearly the thumbscrew design is less hassle. I have a 28940 also and while I was able to get a reasonable adjustment on the cross and compound dials, I am planning to tear into them both and do some massaging. Too many projects at the moment though. :tranquility:
Mark
 

DiscoDan

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#10
Issue resolved for now but the way this assembly is put together seems less than ideal. I may look for the other style since the are not real expensive. Thanks everyone.
 

mickri

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#11
How did you resolve the problem? Just curious. In reviewing your picture and a parts diagram for your lathe (which is different from mine) this is how I would assemble the parts. The lead screw would go through the face plate. Then I would put the washer on. Then I would screw the sleeve/nut onto the lead screw. Don't know how thick your washer is but there appears to be an indent (maybe wrong term) on the head of the sleeve/nut that the washer may fit into. Then the dial which should slip over the sleeve/nut. Next the knurled washer would be screwed onto the sleeve/nut. Then the serrated lock washer. Then the keyed handle and finally the nut. Tightening the final nut would force the handle against the serrated lock washer which would then lock the sleeve/nut in place on the lead screw. Don't know if this is the correct order of parts. Just my best guess.
 

DiscoDan

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#12
Mickri, with one exception you are correct. The washer goes on the threaded nut before the dial, otherwise the back of the threaded nut would not stick out far enough from the dial to ride against the face-plate. The large end of the threaded nut has a smaller raised washer-like surface. The issue I was having appeared to be that as I turned the assembly clockwise it was continuing the thread itself toward the face plate and it was locking up. On reality I just had the compound all the way in so it couldn't move any further. Once I had just the threaded nut on by itself I could see it wasn't moving and what was really happening.
 

mickri

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#13
Glad to hear the you got it figured out.
 

wa5cab

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#14
DiscoDan et al.

I just reviewed all of the parts lists that we have and found them to all be wrong. This includes the cross feed screw assembly as well. The parts used are the same on both, except for the cranks and the plate that attaches to the compound slide or the what's called a bearing that screws into the carriage. The exploded view parts drawing shows the dial as first onto the screw and then the shouldered bushing. The bushing should be first and then the dial.

The final version is a definite improvement. If I had one of the early version 1/2" bed lathes, I would buy the parts and convert it.
 

DiscoDan

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pdentrem

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#16
That looks like a 10”. I thought the 12” was 1” higher at the toolpost area.
 

DiscoDan

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#17
pdentrem, that is OK with me because I think that extra inch would render my bxa too tall.
 

wa5cab

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#18
Yeah, kinda strange that they never fixed the error. However, aside from what sounds like excessive wear on the inner face of the dial, the compound itself is significantly better than the one on the 10” or 3/8” bed 12”. I definitely would not recommend trying to change back to one of those. What I would recommend doing is acquiring just the later version parts that go onto the compound feed screw and the cross feed screw. With those parts and a little care, you can reduce the feed screw thrust bearing assembly end float to almost zero. Then all that you have to deal with is the end float between the screw and brass nut. And you can zero the dial by simply loosening the knurled head thumb screw, turning the dial around to zero, and re-tightening the screw. No muss, no fuss.



Robert Downs
 

DiscoDan

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#19
Robert, do you have a model number in mind? Looking on Vintage Machinery there is a 101.28990 that is newer and has different hardware than mine and similar to the older models. There is also 101.28900/201.28910 that has the same as 101.28990.
 

wa5cab

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#20
Yeah, kinda strange that they never fixed the error. However, aside from what sounds like excessive wear on the inner face of the dial and on the plate that bolts to the rear of the compound slide, the compound itself is significantly better than the one on the 10” or 3/8” bed 12”. I definitely would not recommend trying to change back to one of those. What I would recommend doing is acquiring just the later version parts that go onto the compound feed screw and the cross feed screw. You will then have the final version of the carriage assembly, which is the best one that Atlas ever made. With those parts and a little care, you can reduce the feed screw thrust bearing assembly end float to almost zero. Then all that you have to deal with is the end float between the screw and brass nut. And you can zero the dial by simply loosening the knurled head thumb screw, turning the dial around to zero, and re-tightening the screw. No wrenches required.



The other improvements made in the final version are the lever operated power cross feed (which after drilling and tapping two holes in the apron, is retrofitable to the earlier version that you have). And a slip clutch and non-frangible right lead screw bearing, both also retrofitable.

Also, it's just my opinion, but I think that the AXA is a much better fit for the Atlas 12" than the BXA. And 3/8" square cutter holders and inserts are less expensive than
 

wa5cab

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#21
The model numbers of the final version Atlas 12" are 3985, 3986, 3995 & 3996 and of the Craftsman versions (only difference being the badges) 101.28900, 101.28910, 101.28980 and 101.28990. The first pair in each group are bench and the second pair cabinet models.
 

DiscoDan

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#22
I checked out the Sears parts direct and it appears none of the "final version" parts are available from them. The bushing "may" be available but I tried ordering one for my current setup and it turned out not available. I haven't checked sources specifically for Atlas. Not too big of a deal though. You can get two versions of the dial on ebay and the nut should be fairly easy to make myself. The rest you can find elsewhere.
 

wa5cab

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#23
Clausing still sells a fair number of Atlas lathe parts, and a few mill parts. You will probably think that the prices are high, but they simply reflect typical prices for recently made parts made in USA and not China. And they are usually lower than any prices quoted by Sears.

Also, if Clausing no longer carries a part, they will usually email you a TIFF scan of the original drawing. We have a lot of those part drawings in Downloads, many of them cleaned up by me. But none that I can recall of the specific parts that you are looking for.

At any rate, the threaded bushing, flat washer and dial are the only parts that you need to make the conversion. The cross slide and compound lead screws, cranks, gears, keys, outside nuts, etc., remained the same. And it is possible that you might be able to convert the dial from early to late version. Clausing probably has the knurled thumb screw that locks the dial, as it was also used on the Atlas Mill.

I can definitely recommend the conversion to anyone with the early version of either the Atlas or Craftsman 1/2" bed 12".
 
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