Single Point Thread Repair

[wrmiller]

I have only done this once, many, many years ago. I think I remember most, but I'm unsure if I have to align with a number on the thread dial?

I'm attempting to repair .575x40 tpi

Thanks.

 

[mmcmdl]

Engage for threading on the # first and pick up the thread with the compound .

 

[SLK001]

Yes, as said above. Also, be sure to advance the apron under the lead screw power in order to take up all slack. At 40 TPI, any slack will guarantee complete destruction of what you have done up to now. If you're unsure of what number on the thread dial to use, just engage the lead screw on any number, then leave it there and thread like it was a metric thread.

 

[OTmachine]

As stated,” Pick up the thread with the compound” and the cross slide using the same thread dial number repeatedly. Once the lead screw is engaged, you can stop the spindle to fine adjust the compound and cross slide, ( setting cross slide zero when tool is centered in thread). Back off cross slide, move back to start, feed cross slide to zero, pick up thread dial number, clean up threads.

 

[benmychree]

You don't say what lathe you have, but the general rule is; even threads, close on any line, odd threads on any number, half threads on opposite numbers, quarter threads on one number (only), threads that a factor of the leadscrew can be closed anywhere on the dial., this works for lathes with 4TPI leadscrews.

 

[xr650rRider]

I have only done this once, many, many years ago. I think I remember most, but I'm unsure if I have to align with a number on the thread dial?

I'm attempting to repair .575x40 tpi

Thanks.

Watch Joe

 

[wrmiller]

You don't say what lathe you have, but the general rule is; even threads, close on any line, odd threads on any number, half threads on opposite numbers, quarter threads on one number (only), threads that a factor of the leadscrew can be closed anywhere on the dial., this works for lathes with 4TPI leadscrews.

Sorry, it's a 8 TPI leadscrew.

A friend threaded a 1911 barrel with a .575x40 die, but somehow the threads are not concentric with the barrel bore. He cut one side of the barrel deeper than the other?! He did this once before (not as bad), but I had my PM1340GT back then and managed to fix it. But I just looked in the manual for my little SB1001 and it only goes to 32 TPI, so I can't do this.

Thanks for the info guys.

 

[SLK001]

But I just looked in the manual for my little SB1001 and it only goes to 32 TPI, so I can't do this.

Perhaps with a different spur gear you can get to 40TPI. Is a SB1001 lathe like those little handheld sewing machines? You know, good looking, but not worth a dammm?

 

[Smithdoor]

I have only done this once, many, many years ago. I think I remember most, but I'm unsure if I have to align with a number on the thread dial?

I'm attempting to repair .575x40 tpi

Thanks.

One way have repaired threads if smashed. Is flip a HSS tool upside-down and press the threads back in to shape.
Great fine threads and have on 8tpi too. Saves making a new part.

Dave

 

[Smithdoor]

I have only done this once, many, many years ago. I think I remember most, but I'm unsure if I have to align with a number on the thread dial?

I'm attempting to repair .575x40 tpi

Thanks.

If you cut the thread it may give a problem as it make the thread size small.
To chase a thread put compound at 90° and engage the haft nut. Turn on lathe and let feed for few seconds. Then use compound to line-up the thread with cutter.

DO NOT USE 29.5° you need your compound for lining up the thread.

Dave