Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: lrgoodger on March 20, 2016, 07:11:29 PM

Title: Can't generate G code for this simple dxf...
Post by: lrgoodger on March 20, 2016, 07:11:29 PM
When I first learned about Mach 3 I was excited.  It looked like I would be able to put my experience with computers and programming to use, so I put all this time and effort into converting this old Bridgeport CNC to Mach 3 and I can't manage to convert the simple attached dxf figure (which I drew and generated with Inventor in just a few minutes) to G code for engraving onto a surface.  LazyCam won't do it and the Ace Converter program I downloaded won't do it.  The whole idea behind becoming Mach 3 capable was so I wouldn't have to key in G code a line at a time.  What is the solution?

(https://sites.google.com/site/fixitengineer/home/Atom.jpg)
Title: Re: Can't generate G code for this simple dxf...
Post by: ger21 on March 20, 2016, 08:10:17 PM
Post the .dxf and I'll tell you why.
Does inventor give you an option of saving as v12 dxf? If so, try that.
Title: Re: Can't generate G code for this simple dxf...
Post by: lrgoodger on March 20, 2016, 09:49:14 PM
It saves as an Autocad dxf.  I can save in Autocad 2010, 2007, 2004, 2000 or R12.  I think the problem is the ellipses.  I tried saving a dxf of just one of the three ellipses and couldn't get it to translate.  Probably too many points for the converters to handle.  I can approximate the ellipses pretty closely with circular arcs of the correct size chained together, but what a PITA of a way to do this.

Hmmmm.  You got me thinking.  I saved it out as an R12 dxf and it converted.  It looks like about 130 point straight line approximation of the ellipse, but that is close enough for my purposes.  I can get it from here.  Thanks.
Title: Re: Can't generate G code for this simple dxf...
Post by: ger21 on March 20, 2016, 09:52:14 PM
LazyCAM and ACE can not read ellipses.

R12 does not support ellipses or splines, and converts them to polylines on export.
Title: Re: Can't generate G code for this simple dxf...
Post by: lrgoodger on March 20, 2016, 10:07:12 PM
Is there a better converter that will do ellipses for a retired guy on a fixed income?
Title: Re: Can't generate G code for this simple dxf...
Post by: ger21 on March 20, 2016, 10:17:54 PM
I don't use ellipses, so I'm not sure. I draw in AutoCAD, and it has an option to use arcs for ellipses.

Ace is probably over 10 years old, and LazyCAM not far behind it. Something more modern probably does, but I'm not sure at what cost.
Title: Re: Can't generate G code for this simple dxf...
Post by: robertspark on March 21, 2016, 02:29:11 PM
Why don't you just explode the object?

I find that when I export to DXF the object is a 3d object and sheetcam does not like it, hence I will explode it.

Provide a copy of what you have created and let me have a look at it.

What depth do you want it engraved + with what tool?

Is it a v-carving tool?

What are you machining it in (did you have a feed speed and a spindle speed in mind....)
Title: Re: Can't generate G code for this simple dxf...
Post by: ger21 on March 21, 2016, 03:03:07 PM
Can you explode a drawing from Inventor? I wouldn't think so.
In AutoCAD, you can't explode an ellipse.
Title: Re: Can't generate G code for this simple dxf...
Post by: robertspark on March 21, 2016, 03:19:48 PM
From inventor, export the part to dxf, then explode the dxf
It may be polylines that the gcode generating software is not happy with, not the ellipse object itself.

I'll draw one later and see what sheetcam does (kids 2 bed first...)
Title: Re: Can't generate G code for this simple dxf...
Post by: ger21 on March 21, 2016, 04:29:57 PM
What  are you using to explode the .dxf after you export it?
Title: Re: Can't generate G code for this simple dxf...
Post by: robertspark on March 21, 2016, 04:48:50 PM
AutoCAD (one of the full version variants, not LT), why
Title: Re: Can't generate G code for this simple dxf...
Post by: ger21 on March 21, 2016, 05:54:53 PM
Seems like a hassle to export a .dxf, then load it into autocad, explode it, and then export again.

Not everyone may have a program that can import and explode .dxf files.
And personally, in 20 years of using AutoCAD for CNC, the only time I've ever had to explode anything was a mesh for a CAM program that could only read 3D faces.
Title:
Post by: pstemari on March 23, 2016, 07:38:10 PM
Generally Mach3 processes g-code, but won't produce it. Something like CamBam will take a .dxf file and let you define machining operations (eg profiling, pocketing, and drilling) that use the geometry in the drawing. Once you've defined what you want to do, CamBam will grunt out the g-code.

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