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Ursine
04-14-2005, 12:04 PM
I'm designing some 3d puzzles in Lightwave 3D. It's probably not the best software for this, but I been using it for about 13 years and I'm pretty comfortable with it. I can export as a dxf (2d flat), but the path is not what I expected. Any help would be appreciated.

Thanks,

Dave

ger21
04-14-2005, 12:49 PM
Can you post the .lwo file? I'll take a look when I get home tonight. I have LW8.

I think you'll have to kill the polygons and make curves with the points, but I'm not sure.

I'm assuming you just want to make 2d cuts (2.5D), right?

Ursine
04-14-2005, 02:02 PM
Sure thing. Here's the .lwo and the .dxf created in LW8 using the dxf exporter from dstorm's site. Although with some tweaks it now converts much better, there is still a break in the profile at the head of the curve. It also looks angular, like it was a poly made with points instead a smooth curve.

Yes, I just want to cut out the shape.


Thanks,

Dave

Ursine
04-14-2005, 02:51 PM
I think you're right about killing the poly. Even though the curve is smooth thru the points, the dxf is showing straight segments between the points. So I freeze the curve, kill the poly and create a closed curve from the points.
I then edit the g-code file to end up where it starts out. Still have to figure the Z axis. Now if only I can get the machine built... :)

Thanks,

Dave

ger21
04-14-2005, 03:01 PM
I noticed that DStorm has a poly2curve plugin. Have you tried that?


Why do you have to edit the g-code? As for the Z-axis, click on the layer button when importing and enter the depth you want.

Ursine
04-14-2005, 03:49 PM
I'll download from their site later and check it out. It seems like my toolpath didn't end up where it started. there was always a small gap.
As far as the Z axis, I'm new to g-code and am quite lost. Can you suggest any online info?

Thanks,

Dave

ger21
04-14-2005, 07:54 PM
Ok, I played around a bit, and it doesn't look good. The reason you're getting the break in Mach2 has something to do with, either the way the .dxf is being saved, or the way Mach2 is converting it.

It doesn't seem possible to export any .dxf's from LW with arcs in them, straight segments only. I think the reason is that LW's curves are something like splines, which the .dxf exporters don't support. And even if they did, I don't know of anything that converts splines to g code without converting into straight segments.

I don't know exactly what I did, but You can Freeze it twice (You might have to make it a curve again after freezing) which will give you many more segments which will make it appear as though it were curved. Another option I tried, was exporting an .eps file, bringing it into CorelDraw, and exporting the .dxf from there. Mach2 seemed to like CorelDraw's .dxf a bit better, not leaving the gap you had.

What do you want to know about the Z-axis? Typically, you set Z= 0 to the top of the workpiece, and -Z is going down into the part. When you import a .dxf into Mach2, click on the "Layer Control" button, and you'll see which layer(s)contains objects. IN the field thats says "Cut Z coord." enter the depth you want to cut the part. -0.5 for 1/2" deep. That's all there is to it. You can also use the multipass option in Mach2 to cut in multiple steps.

Ursine
04-14-2005, 10:25 PM
Wow, thanks for troubleshooting that for me. Are you saying that the dxf format will not give me arcs between points or is the problem in LW's exporter. Is there another format you know of I can export from LW and into Mach2 that will support arcs? .stl maybe?

Knowing that it's not doing what it should bothers me a bit, but in all honesty for the wood cutting I'll be doing I'll never see the difference.

Thanks for all your help,

Dave

ger21
04-15-2005, 12:20 AM
It's LW's (and DStorms) exporter, not the .dxf format. Lightwave is not a good choice for doing 2D cnc work. .stl is 3D only, all it is is triangles. Mach2 will only import .dxf and HPGL, I think. If you have something to translate .eps to dxf, exporting eps from Lightwave is probably the best way to do it. I just got an email from Newtek about 8.3, said something about improved eps handling. probably not export, though.

It's not that it's not doing what it should, it's more like it can't do what you'd like it to.

If I was going to use it for 2d CNC work, the .eps will give you the same type of toolpath you would get from a 2D cad program using splines.

Ursine
04-15-2005, 02:27 PM
Gerry,

Thanks for the help. If it proves to be a problem, I'll move to another program for the designing.

Thanks again,

Dave