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Author Topic: Cutter compensation and fixture offsets problem??  (Read 7640 times)

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Offline Sage

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Cutter compensation and fixture offsets problem??
« on: December 02, 2008, 02:20:02 PM »
Why does this code screw up? <attached>
I used a wizard to cut a circle in order to counterbore a 1/2" hole to 0.58 inches. The code uses cutter compensation. It works fine.
 I duplicated the code for a second hole right next to the first and used a fixture offset to get to the second hole. The second hole is a complete mess. (at least the toopat display says so)
Granted I'm a rookie at G-code but I can't see the problem.
 
Note: to Hood and Gram W. As much as I appreciate it, please don't re-write new code. I'd like to learn why this particular code does not work as a learning exercise.

 ;)

Sage

Offline Hood

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Re: Cutter compensation and fixture offsets problem??
« Reply #1 on: December 02, 2008, 02:53:06 PM »
Not much chance of me re-writing the code, there would be no chance of it working if I did  ;D

Hood

Offline Hood

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Re: Cutter compensation and fixture offsets problem??
« Reply #2 on: December 02, 2008, 03:04:41 PM »
Just thinking about this, not actually looked at the code yet but have you tried running it in air as I seem to remember toolpath display  problems with things like this.
Hood

Offline Sage

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Re: Cutter compensation and fixture offsets problem??
« Reply #3 on: December 02, 2008, 03:11:52 PM »
Not yet. I'm away from my machine getting some work ready for later.
To say the tool path display is screwey on offsets is an understatement. But the numbers on the DRO's look bad too although it's hard to tell.
I just noticed I called the G52 in the program a fixture offset. I should have said co-ordinate offset. I think the G52 should still work. I've used G52 before exactly like this with sucess.

Comments appreciated.

Sage

Offline Hood

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Re: Cutter compensation and fixture offsets problem??
« Reply #4 on: December 02, 2008, 04:03:11 PM »
Its definitely not right :(
 I use G52 quite often but never use cutter comp, looks like they dont like each other but maybe someone who knows a bit about comp will see the problem.
Hood

Offline RICH

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Re: Cutter compensation and fixture offsets problem??
« Reply #5 on: December 02, 2008, 07:54:10 PM »
sage, is it supposed to look something like the attached? Sorry as I  can't be of anymore help.

Hood,
Could it be a broken pipe........ ???

RICH

Offline Sage

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Re: Cutter compensation and fixture offsets problem??
« Reply #6 on: December 03, 2008, 09:21:21 AM »
Yup:
That's what it's supposed to look like. Apparently it does for you.
Attached is what I get.
Now to figure out why.
This happens to me qute a bit so maybe it's something in my setup or initialization.

Sage
(sorry for the crappy picture)
« Last Edit: December 03, 2008, 11:10:01 AM by Sage »

Offline Hood

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Re: Cutter compensation and fixture offsets problem??
« Reply #7 on: December 03, 2008, 09:48:32 AM »
Rich
 Not sure what you are meaning by broken pipe.

Sage
 I get exactly the same as you and was just presuming Rich had re-writen the code without a G52 but maybe not.

Hood

Offline RICH

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Re: Cutter compensation and fixture offsets problem??
« Reply #8 on: December 03, 2008, 12:50:27 PM »
Sage and Hood,
 I get the same thing in V3.042.020 but the screen shot was from V3.041, thus,
semi-qouting myself from another recent posting  " think the plumber broke the pipe when repairing the faucet" ;) so possibly may be a version  bug in mill also.

Since the wizard was used to generate the first code, I  remember a similar  problem on lead in's ( ?? maybe about a month ago??? ) in the NFS
thread????.
RICH

Offline Sage

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Re: Cutter compensation and fixture offsets problem??
« Reply #9 on: December 03, 2008, 02:30:19 PM »
Re: Lead-ins.
AND I HOPE SOMEONE IS WRITING ALL THESE DOWN so we can hope to eventually get them all patched up..

I ran into a couple of other bugs in the wizzards when trying to make that simple program. I posted one separately in the NFS wizards page.

1. In the circular pocket wizard the description of the direction of milling is incorrect (I think also in the circle wizzard). It says CCW around the pocket is conventional milling. It should actually say climb milling.

2. The actual direction of milling produced in the resultanlt code is also backwards (i.e. you pick CCW it codes CW G2).

3. If you try to do the counter bore of a 1/2" hole to 0.58" with a 1/4" cutter. Theoretically it can be done quite easily. But the wizard creates a leadin line that crashes the cutter into the side of the hole by a whole bunch more than the conterbore can remove. (unless the toolpath is lying again). I never put it to metal.
Sage
« Last Edit: December 03, 2008, 02:32:00 PM by Sage »