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Author Topic: Kerf problems on multiple parts  (Read 2386 times)

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Kerf problems on multiple parts
« on: May 03, 2014, 11:57:14 AM »
Hi all. I'm a pretty new user to Mach 3.

A little about me is I work for a large structural steel fabricator, and I recently custom built a 15'X125' 6 torch oxy fuel table for them. I installed Mach 3 on it and we have been using it since January. We are currently using ProNest to generate all of our cnc files for the burn table. I have managed to work out a lot of the bugs with our system; most of them due to my setup error, but now there is one problem that has me stumped. We are nesting many large plate together on the same sheet of material, my problem I believe is with the kerf compensation. It works perfectly on the first part always, but never on any parts after. If I break the nests up into individual pieces they all work just fine. The problem only occurs with multiple parts in the same program.

What it looks like it is doing is starting out just fine, then  by the time it get the the next corner of the part it is on the wrong side of the line (ie. it started on the left side of the line but ends up on the right side when it gets to the next corner). This only happens after the first part. I have attachted a program that we are having trouble with if anyone would like to take a look. Any help is very much appreciated.
Re: Kerf problems on multiple parts
« Reply #1 on: May 03, 2014, 12:33:10 PM »
I think it is because the D code is not at the right place in your code.

If you use D code to compensate for the kerf witdh, you should use it after the torch is at cut height, put the D code with a lead in, also must have a lead out, then a G40 to cancel the G41.

The machine use the first line of code to compensate the D so it will not compensate on your lead in but rather with your first line of code.


Jeff

Offline ger21

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Re: Kerf problems on multiple parts
« Reply #2 on: May 03, 2014, 01:03:14 PM »
The D is fine, and should be after G41.

I think your issue is with the lead in's, or lack of them. Unfortunately, it's in Incremental mode, and it's hard for me to follow what's going on.
Gerry

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Offline BR549

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Re: Kerf problems on multiple parts
« Reply #3 on: May 03, 2014, 01:08:18 PM »
With tool COMP you MUST allow room for and program for a leadin and leadout for the G41/42 call. IF not you get what you see as the G41 takes the first move after the call as THE leadin to move into comped position so it "will" cross the line to the other side if you do not program a proper lead in /out.

Just a thought, (;-) TP

Re: Kerf problems on multiple parts
« Reply #4 on: May 22, 2014, 09:11:48 AM »
ok, I have been struggling with this problem still. I have managed to capture a video of it on my computer and upload it to youtube. If you watch the video the problem occurs after the lead in of the second circle. The machine cuts the lead in just fine and moves to account for the kerf but at the end of the lead in and the beginning of the circle it does a small loop before moving to cut the circle.

https://www.youtube.com/watch?v=pkffEqdcZ1c&feature=youtu.be

any help is greatly appreciated

Offline BR549

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Re: Kerf problems on multiple parts
« Reply #5 on: May 22, 2014, 11:28:30 AM »
That is USUALLY an indication that you are NOT completing a LEADOUT from the previous cut and MACH3 is trying its best to unwind the leadout in the next move which may be the leading JIGGLE you are see.

You should have a leadin move after the G42 call which you do BUT I do not see a leadout move after the G40 call.  

NORMALLY with torch cutting you do not use ToolComp  As the leadin/outs can make it complicated if not executed properly.  The offsetting is normally done on the CAM side OR if you are hand programming just account for the Kerf in your programming.

AND there are problems in Tool Comp with Mach3. Mach4 has it down pat.

Just a thought, (;-) TP



« Last Edit: May 22, 2014, 11:31:54 AM by BR549 »