Problem threading

[bracketguy]

I don't know if this is the right place, but does anyone have any ideas why this is happening? Every thing is fine on tooling, been doing these for 10+ years n now all of a sudden its getting chewed up, but only in middle...Has anyone had that happen to them, n what was the fix...? thanks

 

[kvom]

Flexing in the center?

 

[MachineTom]

As Kvom stated, flex is the cause. The right side is supported by the center, and the left side is supported by the chuck, That center portion climbs on the cutting tool, and eats the threads.

Less feed per pass, do you really need that much thread? Try threading at higher speed, you could cut partial depth, then finish with a die. If using a die keep the chips cleaned out of the gaps on long threads like you have.

If you were to use a 1 1/2 Inch diameter die, rather than a 1" or 13/16, there is much more room for chips when cutting long threads.

 

[bracketguy]

Thanks for the replies, it turned out it was the material that was bad. For whatever reason that happened, we got a bad batch of rods...Thanks again tho, n I will keep that in mind in future if ever goes bad again.

 

[jwcnc1911]

If i had to cut threads that deep i would probably use a die on material that size.