Unpopular take: That brand new toolpost that failed on me was operator error not the tool

I see everyone bashing the new QCTP from the usual supplier after my buddy’s snapped during a heavy cut last month. But I gotta disagree with the mob here. I run the same model on my Haas at the shop on Industrial Drive and it held fine through a 0.200 DOC in 4140. The problem is people not checking their gib tightness or running way past rated speeds. My buddy admitted later he was pushing 400 SFM with a dull insert. That’s on him not the toolpost. I swapped to a different brand anyway just to be safe but I still think the design is solid for normal ops. Has anyone else actually measured their toolpost deflection before blaming the hardware?

3 comments

3 Comments

violar351mo ago

Whoa, hard disagree here - I've seen enough drawbar torque gauges lie to know that even a good toolpost can fail if the machine itself has any slop in the spindle bearings, and @david_jones38's question about drawbar torque is actually the real issue, not the toolpost design. Your setup might be tight, but most guys running those heavy cuts on older lathes are fighting a losing battle with machine rigidity, so blaming the operator is kind of missing the bigger picture. I'd still trust a drop-forged block over any casting for that kind of work, but your mileage may vary.

david_jones381mo ago

Did you measure your drawbar torque before the cut?

william_garcia1mo ago

Yeah, exactly. That's the one thing nobody checks but it makes or breaks everything.