Z height issue - CAM/Post Processor/Controller/Mill?

New boy alert! Got a weird issue I wanted to run past folk please.

Just ran a prototype part, first op (adaptive clearing went well), 2nd op was a 0.1mm face op... which actually came in an hammered a approx 3mm depth of cut, scrapping the part and nearly giving me a heart attack.

I think the G code is ok which means fusion 360 and the post processor was fine, but as I am rubbish at reading g code I wanted to get advice from more experienced heads so I can rule out Fusion and the post processor please - so can you check the code below and see if you can see any reason it messed up?Attachment 20910

z0 was stock top, which was 0.1 from model top. I'm running a 10mm endmill into alu. This is the exerpt of the face op

(FACE2)
N2559 G0 X86.5 Y3.675
N2560 Z15
N2561 Z5
N2562 G1 Z0.9 F400
N2563 G18 G3 X85.5 Z-0.1 I-1
N2564 G1 X80
N2565 X0
N2566 G3 X-1 Z0.9 K1
N2567 G0 Z5
N2568 G1 X86.5 Y12.255 F4000
N2569 Z0.9 F400
N2570 G3 X85.5 Z-0.1 I-1
N2571 G1 X80
N2572 X0
N2573 G3 X-1 Z0.9 K1
N2574 G0 Z5
N2575 G1 X86.5 Y20.835 F4000
N2576 Z0.9 F400
N2577 G3 X85.5 Z-0.1 I-1
N2578 G1 X80
N2579 X0
N2580 G3 X-1 Z0.9 K1
N2581 G0 Z5
N2582 G1 X86.5 Y29.415 F4000
N2583 Z0.9 F400
N2584 G3 X85.5 Z-0.1 I-1
N2585 G1 X80
N2586 X0
N2587 G3 X-1 Z0.9 K1
N2588 G0 Z5
N2589 G1 X86.5 Y37.995 F4000
N2590 Z0.9 F400
N2591 G3 X85.5 Z-0.1 I-1
N2592 G1 X80
N2593 X0
N2594 G3 X-1 Z0.9 K1
N2595 G0 Z5
N2596 G1 X86.5 Y46.575 F4000
N2597 Z0.9 F400
N2598 G3 X85.5 Z-0.1 I-1
N2599 G1 X80
N2600 X0
N2601 G3 X-1 Z0.9 K1
N2602 G0 Z5
N2603 G1 X86.5 Y55.155 F4000
N2604 Z0.9 F400
N2605 G3 X85.5 Z-0.1 I-1
N2606 G1 X80
N2607 X0
N2608 G3 X-1 Z0.9 K1
N2609 G0 Z15
N2610 G17

I'll add a photo of the physical part.

Would welcome your diagnosis as my suspicion is currently on the controller/machine.

Thanks folks!

I loaded that into the copy of Mach3 on my laptop and the cuts run at z=0.9 with diagonal returns at a higher level.

Quick scan of gcode says it never goes below Z=-0.1, so at first sight it looks like setting error, tool moved in collet, coordinate offset, or some other user or machine problem. It's not in this extract of gcode, anyway. Any more info on what happened leading up to this "event"?

now the tool pullout sounds possible... Before this op it running some adaptive clearing and I noticed the floor had steps in it, getting progressively deeper I thought it was all part of the same controller issue - but it's quite possible the heavy cut I was doing has dragged the 10mm endmill down within the collet. I seated the tool up against the top of the toolholder, so when I am in from work I can check by lossening it up and seeing if it can be pushed up, if it can then that is my issue.

Thanks for your help - any advice on stopping end mills walk out of collets is welcome :D

Quote:

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Originally Posted by Dangle_kt

any advice on stopping end mills walk out of collets is welcome :D

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Check the recommended torque for the collets you are using and tighten to a significant percentage of it, you might find that 50% of recommended is way more than you're currently using when you do check.

If you are using ER collets, I would suggest looking at the ball-bearing version of the closer nut (available from Arc Euro and probably a bunch of other places) - let's you tighten the nut more easily.

well I went and checked, and you were correct - I had tool pullout. Thanks for the pointer