My Z depth is changing anyone experience this


I recently purchased a PCNC 440 mill. I come from a background of tool and die and ahve machined primarily on HAAS mill’s. And I have been noticing a trending issue. I have a program through Fusion 360 and I have my x y and z all set on the part. And only on tool 1 i am noticing after i set my tool heights it runs 3 parts at the perfect depth i have it programmed too. Then on the next part the z depth is not deep enough by .020" so I adjust tool 1 and then it runs it at the right depth again for a couple parts then its .020" to deep and I go back to my original number in tool 1. I am going out my dang mind any one had a similar issue please im begging for advice as my production is down right now until i know what is going on.

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I’d start by making sure your screws are tight on the ; motor to lead screw couplings, motor mounts and the mounts to the main body, spindle mounting, limit switch mounts, limit switch stops. Also maybe unplug and replug all the motor leads. Just a quick once over. I have an 1100 but quick tightening of bolts and connectors solves a lot.


I had a similar issue on a 1100. The z depth would change, then I would check the offset on the tool and it did not change.

The problem was that the tool holder was pulling out of the spindle collet. I started putting a bit more torque onto the drawbar when using an endmill and the issue went away.

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You have knowledge with Haas machines, and you took a big step down to Tormach. The 440 mill has stepper motors not closed loop motors. Consistent cuts and depths will have to be monitored on all of your parts. Know you limits with these machines and you will be happier. If you want consistence buy a Haas or spend more time to maintain your Tormach. I sold my 440 years ago and purchased a baby Haas. Now I only check every 50 parts.

That’s good advice. Don’t try to fix things on your machine, just buy HAAS!
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