9" cross slide issue

Hi all,

I find myself in need of some help with a cross slide issue on my 9" SB. I've been reading the forum for a few years now, but I've never posted as I'm just a hobbyist, and never really had anything to add in the way of advice or answers. Hopefully this will help some other people out with reassembly or rebuilding.

I'm not sure what model the lathe is. It has the two lever, quick change gear box, and apron with the automatic longitudinal and cross feed. This lathe was put together from surplus parts by a machinist, and I believe it did not come with these accessories originally, and I've consulted the army lathe manual, and there are a few more parts in the cross slide parts stack up that aren't listed there.

I recently tore down the carriage so I could clean everything up after a little adventure machining some cast iron. I cleaned the chip pan out first, so if I dropped anything, I would notice, and I wouldn't have to hunt around for it.

Upon re-assembly, I end up with about .040 of "endplay" in the cross slide. I can grab the cross slide and pull it back and forth, and there is a gap between the handle and the dial.


Before taking this apart, there was no gap there, but there was about .015 backlash. The top slide had about .013 backlash, but after re-assembly, there is only about .003, with no gaps anywhere in the assembly.


Here is the cross slide laid out.


I don't notice those washers in front of the bushing in the Army lathe manual. Just after the spline gear on the screw, the two ground washers go on, then there is a little groove. The diameter of the screw changes there, so that the bushing will not slide on all the way and touch the washers. Then there is a washer and needle bearing stack-up, then the dial, then the handle and the nut.

The only way I can see to proceed is to put the assembly together, with the two washers pushed down to the hub made by the spline gear, ( pinion gear?) and the bushing, bearing stack up, dial and handle with the nut screwed on, push the bushing towards the handle end, and measure the gap, make a washer just a wee bit more than the gap in width, and use the nut to adjust the end play.

The only problem with that, is that I've had the handle on and off in the past and never had to adjust anything, it was always just snugged down tight. So I'm a little perplexed.

Can anyone see what should probably be slapping me in the face here?

Well, it's obviously been modified...so it is not a stock configuration.

That said it can be a very nice modification, what I am suspecting is you have lost a ball bearing carrier that would have gone between those two washers on the front end...maybe double check for that.

If you can't find it(if there was one) there is really no point in having a bearing on one side and not the other.

That being the case I would pull it back out and put it together without the 2 washers in place at the gear end then slide everything back tight against the handle and get a measurement of the gap.

there is a bearing set and it is Boston Gear part number 17195...that is the ONLY bearing currently produced that is a good replacement...it's about 12 bucks from MSC last I ordered them.

Here you go, 3/8" inside diameter, 11/16 outside diameter,9/32" thick

3/8 Inch Inside x 11/16 Inch Outside 3548591 - MSC

If your gap is too small to squeeze it in then you may simply face off the end of the gear portion to make room for it. If the shaft is as you say a bigger diameter there just turn it down a bit so the new bearing will slide on.

Easy and very satisfying little project, and you can completely eliminate backlash sources at that end of the assembly.

To do it you will of course have to lock your cross slide via the gib screws and set your compound to make the facing cuts.

If this is clear as mud, let me know- sometimes I have difficulty typing and can get things a bit mucked up.

iwananew10K said:

...what I am suspecting is you have lost a ball bearing carrier that would have gone between those two washers on the front end...

Click to expand...

Hah! You think? Look what I found...

That was down in the oil reservoir at the bottom of the apron. Funny story how I found it.

Thanks for the link too. I had looked all over for a thrust bearing that would fit and couldn't find any.

So I went and turned a washer to fit, and tested it out and it worked, so I was going to leave it for awhile and see what might come up on the forum here. I checked out the link to the thrust bearing, but since I had just measured the OD on the washers that are in there at .682, I wasn't sure that it would fit since they look like some precision washers, and I just assumed that they were .682 for a reason.

I pulled the screw assembly out, put the washers on the handle end, and put that through the hole in the saddle to see if there was a little shake, there was, and so I was then going to turn something to 11/16 and make sure that fit. As I was pulling out the screw, the washers caught on the side of the hole and dropped into the apron.

So, I took the saddle off, and fished out the washers which were still sitting right on the top there, and while it was off, I thought I would just top off the oil reservoir. The thread for the little 90° oil cup is pitched downward so steeply that the cup acts like a trap, and I have to drip oil in a little at a time so it clears the thread end, and makes its way into the reservoir. So I got my oil can, and when I went to put the oil in the reservoir, there was the bearing staring up at me! It must have come off when I took the screw out during the dis-assembly/clean-up and sat in the thru hole in the saddle. And then fallen into the oil reservoir when I was putting everything back together.

So, once I get that all put back together, I'm in good shape.

Thanks!