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Author Topic: DXF files, 0,0 and Mach3  (Read 5425 times)

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DXF files, 0,0 and Mach3
« on: December 23, 2005, 09:09:04 PM »
Hi all, newbie here and have a question.  Just started using Mach3 and probably don’t know enough to ask the right question to solve the problem, but here goes…If this isn’t the right place for the answer, let me know.
The problem I’m having is were 0,0 ends up when the G-code is generated. 
Started importing DXF files into Mach3 for profiling and such.  When I draw the 2D part in AutoCAD 2000LT I place 0,0 (World) at some logical location such as the center of a hole or edge of a feature.
When the file is imported into Mach3, I tell it to optimize it.  When the G-code is generated, 0,0 ends up at some point away from the part (usually a short distance in the –y and –x direction) and the first move is toward  the feature edge.  This is great to look at and watch the tool path, but I have no idea where the 0,0 point is on my mill table in relation to the tool (z-0,0). 
The work around for me so far is to calculate the first (start) point in the G-code. Then move the part relative to the tool and the mill table using my non-MAch3 DRO and starting the G-code from there.  There has to be a better way.
It would be nice if I could tell Mach3 where to put 0,0 (such as where it was in the cad file).  What am I missing here.  How do I control where 0,0 is?
Thanks in advance,
Tadd
Tadd
MIL-TFP41

Offline DAlgie

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Re: DXF files, 0,0 and Mach3
« Reply #1 on: December 24, 2005, 04:27:54 PM »
Sounds like you are not actually using world as your UCS, you said you were placing 0,0 at some logical position, you can't move world in Acad, you have to move the drawing to world. If you were placing your UCS somewhere then it's not the world UCS.
Re: DXF files, 0,0 and Mach3
« Reply #2 on: December 24, 2005, 06:21:37 PM »
Hello again,
I miss-spoke in the post.  I draw the object and then move it to world 0,0 so the center of the hole is at 0,0.  Am I missing something inso far as I should know were the software (Mach3) thinks 0,0 is in relation to the tool and the table?
Tadd
Tadd
MIL-TFP41

Offline DAlgie

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Re: DXF files, 0,0 and Mach3
« Reply #3 on: December 24, 2005, 11:51:52 PM »
Problems I have had with other CAM systems can be: you must use DXF from version 12 Acad, others will give different results, there are quite a few DXFs but R12 is the best one most use, if you mirror a part then some of the lines, arcs, etc. won't mirror. Also, moving the drawing to world 0,0 is a no no, start your drawing where you want it to end up. Some CAMs don't like polylines and will only support lines and arcs. My guess is that your problem is that you moved the drawing to it's location. Redraw it where it should be and try again. Oh, one thing, when I say R12 Acad, there is an option for DXF export that will let you choose what version you want, pick R12 there, I wouldn't want to be using R12 either!
Re: DXF files, 0,0 and Mach3
« Reply #4 on: December 26, 2005, 06:56:25 AM »
Thanks,
I'll try that, I wondered about moving things after their drawn and how AutoCAD handles the move in relation to World 0,0.  At save time there is an option to save in Rev 12, I've been saving in Rev 14.  Thanks for the info, when I get a chance, (have to take SWMBO shopping today), I'll try it and report back.
Tadd
Tadd
MIL-TFP41
Re: DXF files, 0,0 and Mach3
« Reply #5 on: January 05, 2006, 09:13:51 AM »
Hi All,
Finally got back to this after the holiday.  Went back and did some tests to see what effect moving things after their drawn would have on how Mach3 imports the DXF file and the resulting G-code.  Turns out, any G-code that Mach3 generates is based on where the feature was ORIGINALLY drawn in relation to World 0,0.  If I want the tool to start at the center of a feature, I must draw the feature with World 0,0 at were I want the tool to start.  Can't draw the feature and then move it to 0,0.  Also, the version of AutoCad DXF file I saved it in didn't seem to make any difference.  Hope this helps others who are still on the learning curve.
Tadd
Tadd
MIL-TFP41