Lathe Cross Slide Problem

[PixMan]

Ed, that thing looks like it was made as an afterthought. ;) I can only assume they put the slot there because they didn't want to interfere with the tapped hole for mounting.

See how the thread is deformed so badly from distorting the thin piece of bronze in that way? All the more reason to make it a little differently/better. I can slot it with something 1/8" or less at the halfway point from the ends and put the set screw in the same orientation, though off center so you can use two mounting screws.

Mine is set up with three holes in line on the top of the cross slide. One is a counterbored clear through hole. The middle is the cone point set screw that spreads the "two halves" (though they're still connected) and the third hole is actually a slightly elongated one, a counterbored slot. To adjust backlash, leave the first one tight, always, then loosen the third (slotted) one. Snug up the middle set screw, tighten the third (slotted) one. There's only perhaps a millimeter of slot length, because the nut would be broken into two pieces if you need more than that.

[EdK]

(04-28-2014, 09:44 AM)PixMan Wrote: Ed, that thing looks like it was made as an afterthought. ;) I can only assume they put the slot there because they didn't want to interfere with the tapped hole for mounting.

See how the thread is deformed so badly from distorting the thin piece of bronze in that way? All the more reason to make it a little differently/better. I can slot it with something 1/8" or less at the halfway point from the ends and put the set screw in the same orientation, though off center so you can use two mounting screws.

Mine is set up with three holes in line on the top of the cross slide. One is a counterbored clear through hole. The middle is the cone point set screw that spreads the "two halves" (though they're still connected) and the third hole is actually a slightly elongated one, a counterbored slot. To adjust backlash, leave the first one tight, always, then loosen the third (slotted) one. Snug up the middle set screw, tighten the third (slotted) one. There's only perhaps a millimeter of slot length, because the nut would be broken into two pieces if you need more than that.

Ken,

I think I've got the picture now. After thinking about it, that's kind of how I thought it would work. I'll draw it up and post it to make sure I understand the details.

Thanks!

Ed

[EdK]

Ken,

Does this look like what you were describing? That's a top view and a side view of the cross slide where the nut mounts to.

Ed

   

[EdK]

New nut drawing attached.

Ed


  nut_03.pdf (Size: 9.78 KB / Downloads: 12)

[PixMan]

Perfect! Nice job Ed!

I'll get going on it ASAP. I can't make any promised delivery date because I'm trying to finish up a project of re-doing the living/dining room at my home. When I bought the house some 25 years ago, it had mostly suspended ceilings and I'm just getting to the biggest room to put up a real, solid ceiling. Of course with that I have to paint the whole thing from top to bottom. What a chore!

[EdK]

No problem Ken. I'm in no hurry.

Ed

[Mayhem]

Get Ed to come paint for you.

[PixMan]

Finished up the screw today, shipping the set out to Ed (hopefully) tomorrow.

The last operation after turning was to mill the flat, easily done with my new-to-me square 5C collet block.



Fitted to the screw, there's just a touch of play at either end, firm in the middle. It may be just a .001" bow, no more than that. Or, it could be the screw was a little dirty, as the second time I tried it the fit seemed better.



Close-up of the screw thread, a 5/8-10 LH Acme. Done with a lay-down threading insert, Carmex 16EL-10ACME grade MXC.



And one of the M12x1.5 6g, done with a Vardex 3ER-1.5ISO grade VTX.



Overall, I'm happy with it and pleased that the project really only took two sessions in the shop, about 3 hours each piece. Well, three sessions really because I missed the second posting of the screw that Ed had posted and had to go back to take off another .0024" to bring in the .350" dimension for the flat.

[EdK]

Very nice!

I can't thank you enough Ken. I look forward to receiving the parts and getting them installed on the lathe.

Ed

[DaveH]

That does look very nice Ken

DaveH