Fixing bent lead screw in tailstock ram

[MKepke]

The lead screw controlling the in-out action of the ram in my vintage Delta Heavy Duty lathe is bent.

The bend is a couple of degrees off straight and it binds up tight in the ram after threading in about an inch. I think it should go in much further. I suspect some of the female threads may be galled and that led to the bending.

I plan to try carefully bending the screw back to straight in a typical 3 point bending set up with a bit of copper or aluminum pipe over the threads. Maybe a little heat too. I’ll chase the female threads with a tap.

If anyone has a better idea for straightening a 1/2-13 LH lead screw, let me know.

Can only blame this on operator-error but I do wish Delta had used a larger diameter screw with a stronger thread, like an Acme screw.

-Mark

[barryvabeach]

Mark,  no better ideas, but agree a little heat may help.

[Tapper]

The lead screw controlling the in-out action of the ram in my vintage Delta Heavy Duty lathe is bent.

The bend is a couple of degrees off straight and it binds up tight in the ram after threading in about an inch. I think it should go in much further. I suspect some of the female threads may be galled and that led to the bending.

I plan to try carefully bending the screw back to straight in a typical 3 point bending set up with a bit of copper or aluminum pipe over the threads. Maybe a little heat too. I’ll chase the female threads with a tap.

If anyone has a better idea for straightening a 1/2-13 LH lead screw, let me know.

Can only blame this on operator-error but I do wish Delta had used a larger diameter screw with a stronger thread, like an Acme screw.

-Mark

Do you have a photo of the screw you could share with us?

Doug

[hcbph]

Do you have a photo of the screw you could share with us?

Doug

If you have any 'good' machine shops in your area, it should be a walk in the park for them.  If not the 3 point idea works but be careful in the orientation of the thread when putting pressure on it.

[Timberwolf]

The lead screw controlling the in-out action of the ram in my vintage Delta Heavy Duty lathe is bent.

The bend is a couple of degrees off straight and it binds up tight in the ram after threading in about an inch. I think it should go in much further. I suspect some of the female threads may be galled and that led to the bending.

I plan to try carefully bending the screw back to straight in a typical 3 point bending set up with a bit of copper or aluminum pipe over the threads. Maybe a little heat too. I’ll chase the female threads with a tap.

If anyone has a better idea for straightening a 1/2-13 LH lead screw, let me know.

Can only blame this on operator-error but I do wish Delta had used a larger diameter screw with a stronger thread, like an Acme screw.

-Mark

.............
I am probably preaching to the choir but it is important to determine the start of the bend and chalk it so as not to introduce a compound bend in the straightening process...Instead of copper or aluminum, I would opt for lead...Old Machinists used a lead hammer for straightening shafts in lathe chuck...I still have my lead hammer...they can deliver a lot of "smack" without damage. A "dead blow" hammer can also work well to reduce rebound. Good luck..let us know the result, Mark.

[MKepke]

As requested a couple pix of the item in question

Per the pictures, it has about 12-15 thou of bend. I'm assuming the bend is what's causing the binding in the female threading of the ram itself.

Earlier I checked the female threads in the ram with a tap and they're fine.





-Mark

[Tapper]

Thanks for the pics. You have a metal lathe?

Doug

[MKepke]

Well, after some careful persuasion with a C-clamp, the lead screw is straightened enough to make the ram operable again.

Now that I have it back together, I'm reminded how much slop there is in the fit of the male and female threads. Probably due to generations of schoolkids running the tailstock quill without any lubrication.

I hope Tapper isn't going to suggest I make a new leadscrew, because I just might be talked into that. With Acme threads, like God intended lathes to have.

-Mark

[Tapper]

Well, after some careful persuasion with a C-clamp, the lead screw is straightened enough to make the ram operable again.

Now that I have it back together, I'm reminded how much slop there is in the fit of the male and female threads.  Probably due to generations of schoolkids running the tailstock quill without any lubrication.

I hope Tapper isn't going to suggest I make a new leadscrew, because I just might be talked into that.  With Acme threads, like God intended lathes to have.

-Mark

Yep, that's precisely what I was suggesting. Acme threads might work. Not quite as precise, but might work. In any event, glad you were able to get an acceptable result.

Doug