Thread: AutoCad 2007
Polylines = Good
I use polylines exclusively and Vectric's software works 100% of the time with my drawings.
Say you have a rectangular shape, and you want to start in the middle of the edge.
Here's what I do.
First, draw the rectangle. This will be used as a base for the final part.
Using the polyline tool, use a Midpoint or Nearest snap at the point you want to start. Then, click on the endpoints in the order (direction) you want the tool to go (Use running OSNAPS with Endpoint turned on). After clicking the last endpoint, hit "Enter" to exit the command. Now, delete the original rectangle, which should be visible in the open section of the new , open, rectangle. Then, select the new one, right click and choose polyline edit, and choose close.
Save as .v12 dxf and you should be good to go.
I actually use a macro that I wrote which exports g-code from within AutoCAD.
I looked at polylines, figured out how one magic number could define an arc but never wrote the interpreter. I just explode them before I export.
I found the trickiest bit was where the tool was too big to fit in all the little nooks and crannies, meaning I had to discard lots of entities. I did it, nearly, but should a pocket have a constriction below tool diameter I only get half of it. I found picking up on a sub-pocket surprisingly tricky, too easy to get phantoms. Remembering that a subsequent tool might have to do waste removal only on the uncut section was beyond me.
Last edited by Robin Hewitt; 04-08-2012 at 09:09 AM.
For me, using polylines means I didn't have to figure out how to join lines and arcs. The downside is that it forces the user to know exactly what he wants to do, as you basically are drawing your toolpaths. It took me about a week to get that magic number (Bulge) into IJ g-code.
I try to avoid as much math as possible. So there's no pocketing, other than circles, which are easy. I rarely do any other pocketing, and if I need to, it only takes a minute or two to draw the pocket toolpaths. (A few offsets, and then trace with a polyline).
I have a test version that let's me assign machining order to entities, and have plans for multiple tools. But I'll probably need to learn VB.net first, as I've found that 64bit AutoCAD does not run VBA code as efficiently as 32bit AutoCAD does.
I probably wouldn't know VBA if it jumped up and bit me in the knee, sounds like AutoCAD will remain a closed door to me.
Perhaps that is why you had problems stitching lines and arcs in to closed loops, it's easy in C#.
I wanted everything defined in the drawing and one easy to edit text file so I could avoid a whole mess of buttons
Can't argue with that
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