Threading problem

[lancexxx]

I am having an issue I can't figure out. When I thread I use the compound slide. I come in and touch. Zero my dial out and also my dro. Turn in a few thousands make a pass pull out go back and go to zero turn in a few more thousands make a cut and repeat all the steps maybe 20-30 thousands and all the sudden it takes nothing off. Might make that pass a few times and nothing then the next time it might cut. If you keep feeding in it will take it all at once, or sometimes start cutting half way down the threads. I'm not a machinist or gunsmith but do some barrell work for myself and friends. I've went over everything I can think of and no answer. The cross slide dial and dro always read the same. Any help would be appreciated. This is a lot to try and type if anybody has an answer and is willing to give a phone no. I will call
Thanks

 

[paperpuncher]

Have you tried the cutting tool just below centerline

 

[lancexxx]

No, I thought of that about 30 min. Ago. It almost seems like it is pushing against the work, but not cutting. That might fix it, I will try that tommorrow.
Thanks

 

[rwk]

Check how much slack you have in the cross slide or when you get down near the end there might be enough pressure to take off material with a light cut.

 

[p17enfeild]

sound like bit of wear in your cross slide screw , or saddle shears

 

[lancexxx]

Thanks guys, but I don't think it is any wear or backlash. Dro and dial read the same. I think problem is solved. Looks like a threading insert not ground right.

 

[jscandale]

Maybe check the gibs...

JS

 

[Hal]

Is your cutter HSS or carbide?

You might have a build up on the cutting edge.

Hal

 

[lancexxx]

New bit took care of it. Thanks to all that replied

 

[lancexxx]

It was hss bit

 

[paperpuncher]

I use HSS as well for most threading. I get a build up on the edge at times I keep a small flat diamond hone handy and touch up the tool as needed.