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Fitting TA to 13, leadscrew issue

Rudd

Stainless
Joined
Jul 30, 2003
Location
savannah, jaw-ja
Fitting TA to 13, Crossfeed screw issue

I'm retrofitting a TA to my wartime 13. The "handle end" of the crossfeed screw that came with the TA was broken off, I found someone selling a newly made one on E-Bay.
It seems like it is set up for some other config than mine - it is about 1.25" too long, and has a .500" dia. section ahead of the .4375 dia section where the dial mounts.
Best I can figure is I need to re-assemble the cross slide and modify the purchased part to work with my standard dial. The seller of the TA "threw in" a large dial, but it is only about .19" or so thicker than the standard dial.
Am I missing something?
My CF bushing on top. Broken part received with TA next, original CF screw in center, newly purchased part on the bottom of the photo. IMG_0956.jpg
 
Is there a "slipjoint"?

A requirement of telescoping T/A

In other words, the screw proper is able to "move" in relation to "handle end"
 
I'm retrofitting a TA to my wartime 13. The "handle end" of the crossfeed screw that came with the TA was broken off, I found someone selling a newly made one on E-Bay.
It seems like it is set up for some other config than mine - it is about 1.25" too long, and has a .500" dia. section ahead of the .4375 dia section where the dial mounts.
Best I can figure is I need to re-assemble the cross slide and modify the purchased part to work with my standard dial. The seller of the TA "threw in" a large dial, but it is only about .19" or so thicker than the standard dial.
Am I missing something?
My CF bushing on top. Broken part received with TA next, original CF screw in center, newly purchased part on the bottom of the photo. View attachment 218439

The new front screw is for the large dial set up. You would need a new bushing, a collar, and a couple thrust bearings in addition to the large dial.
Ted
 
Yes, John, the part shown has a bore with an internal key to fit the screw. I *think* I have that end sorted out - old style, no thrust bearings on the TA end of the lead screw.
Ted, thanks, that makes sense. I think the lathe this stuff came off of got tumped on its front, which probably broke the collar at the same time it broke the CF screw. It probably had the large dial setup, which is why the seller "threw in" the dial.

I wouldn't mind having the large dial set-up.

Here's what I got in the package:
The bushing has marks on the non-threaded in where it was up against the pinion on the crank end of the CF screw. I can't seem to see how it worked - any 2nd bushing sticking out towards the operator would not have much thread to hang on to. I think it is a cut off piece of the broken bushing.
Do you happen to have the correct bushing? Bearings would be nice too but I can sort that out. I'd make the thing, but I don't have a lot of play time.
IMG_0962.jpg
 
Yes, John, the part shown has a bore with an internal key to fit the screw. I *think* I have that end sorted out - old style, no thrust bearings on the TA end of the lead screw.
Ted, thanks, that makes sense. I think the lathe this stuff came off of got tumped on its front, which probably broke the collar at the same time it broke the CF screw. It probably had the large dial setup, which is why the seller "threw in" the dial.

I wouldn't mind having the large dial set-up.

Here's what I got in the package:
The bushing has marks on the non-threaded in where it was up against the pinion on the crank end of the CF screw. I can't seem to see how it worked - any 2nd bushing sticking out towards the operator would not have much thread to hang on to. I think it is a cut off piece of the broken bushing.
Do you happen to have the correct bushing? Bearings would be nice too but I can sort that out. I'd make the thing, but I don't have a lot of play time.
View attachment 218464

Rudd,
I have the bushing, but no bearings.
Send me an email.
Ted
[email protected]
 
Nope. 5/8" ID x 1" max OD. All I am seeing is bronze or steel washers. Should be fine, I have clear evidence there was nothing between the CF screw pinion and the bushing, gear shaped rust marks on what is left of the bushing.
Also just sorted out that the pinion end of the screw I bought is missing a cross hole for the 13 pin to keep the 14 CF sleeve from spinning on the shaft.
Not surprising, one of the supposedly "couple thou under" .625 diameters is .622 on one end and .6245 on the other - over about 3". Makes for a wringing fit in my current bushing. I'll see if I need to take it down a bit when the bushing from Ted gets here.
This has been quite an adventure. In the install instructions - Fig. 10 tells me to check the parallelism of the lathe bed and the TA bed by putting an indicator against the side of the TA bed and sliding it back and forth. Best I can figure that is like Dave Sobel's example where you sweep an indicator on a part on a mill bed, indicator doesn't move, must be flat, right? No, it's a bicycle wheel.
I then found that the side of the TA bed is not only not parallel with the dovetails on the bed, it isn't actually a flat surface according to my surface plate and a little dab of Prussian blue.
I'm going to try to rig up some indicator set up where I can actually test the TA bed dovetails against the ways when moving the saddle, but I am not sure how critical this really is.
Plus side I finally got a good excuse to try my hand at some minor scraping.
 








 
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