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Author Topic: Z movement  (Read 1558 times)

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Z movement
« on: June 18, 2016, 04:43:58 AM »
Ive been lucky enough to have good suggestions here in the past and would really like to clear this up.
Im trying to do a chamfer and I know the chamfer width and chip offset is correct but I dont understand Gcode enough to know why it keeps moving down to around z-7 when Im expecting it to go to around z-3. Ive attached a screenshot to illustrate. I can only see z-2.8 which sounds about right but you can see by the DRO that its actually at z-6.9 so why is that??

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Re: Z movement
« Reply #1 on: June 18, 2016, 08:30:21 AM »
I am not certain it affects your Z axis DRO position but check that your G54 work offsets are set correctly.  Also and perhaps more importantly, check your G43 tool length offsets.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Z movement
« Reply #2 on: June 18, 2016, 10:02:38 AM »
...
I attached a pic showing where the tool was around the same location as in the DRO's so I think thats right but how is it when I zeroed the tool before running the Gcode plus it was fine for all the previous strategies used to machine the part?
Re: Z movement
« Reply #3 on: June 18, 2016, 10:21:42 AM »
And isn't tool offset relating to the tool radius?
Re: Z movement
« Reply #4 on: June 19, 2016, 01:30:35 AM »
Ok so this got me totally stumped. I checked and there were no values in the tool length offset table but this is where it gets weird. I ran the original Gcode that was used to cut the stock just to see where the controlled point went (I knew it was safe as all the material was already removed) but it went to a lower Z point and I knew that it hadnt done that before so I put the original flat end mill back and rezeroed. Now it followed the path I expected.

So this is where it gets weird.... I lifted the spindle roughly 20mm as that was the additional length of the spot drill I was using for the chamfer operations before putting the spot drill back. Now everything works fine so the original question is no longer needing answering. But why on earth would this happen??

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Re: Z movement
« Reply #5 on: June 19, 2016, 04:10:04 AM »
I think you need to look at the CAM software you are using to generate your Gcode.

Just a suggestion, but if you are not going to be using or setting-up the offsets within Mach3 then perhaps exclude those related Gcodes from your generated file.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Z movement
« Reply #6 on: June 19, 2016, 08:01:12 PM »
Will do, thank you so much.

The previous occurrence in strange though