Seriously dumb CAM question

[sploo]

I'm really about to show my ignorance here, but hey, we've all got to learn.

I've downloaded a trial version of MeshCAM, and imported a very simple STL file I'd created (a 1/4" thick sheet with a circle cut out of it).

Generating a toolpath with MeshCAM was fine, and I can load this into Mach or CNCSimulator and see what would happen.

MeshCAM looks ideal for producing pseudo 3D parts - textured surfaces, engraving etc. However, what would I use if I just wanted the cutter to follow the path of the geometry? I ask because I was sort of expecting the CAM program to create a simple cutting path - a circular cut to make a hole, then a few straight paths to cut out the sheet.

[ger21]

You want something like SheetCAM to just cut a hole, or a profile. But, SheetCAM won't read 3D files, only 2D drawings. MeshCAM was designed for cutting 3D surfaces, and it cuts the entire surface, not just specific features.

If your a Mach3 user, you might want to try LazyCAM, free for registered Mach3 users. download the first beta at www.machsupport.com, and watch the video there too. The first release is a little buggy, but looks very promising.

[sploo]

Thanks for the info Gerry!

OK, I've downloaded SheetCAM and run through the first tutorial, and the resulting g-code simulates fine on Mach and CNCSimulator.

I've also downloaded A9CAD, and made a very simple drawing (a rectangle with a couple of circular holes). Running that through SheetCAM produces a very garbled toolpath, so I guess I'm going to have to do a bit more reading. Is there anything simple I'm likely to be missing?

I also downloaded LazyCAM, but it crashes on the PC I'm currently using, so I've not spent too much time with it.

[ger21]

Originally Posted by sploo I've also downloaded A9CAD, and made a very simple drawing (a rectangle with a couple of circular holes). Running that through SheetCAM produces a very garbled toolpath, so I guess I'm going to have to do a bit more reading. Is there anything simple I'm likely to be missing?

When you save the .dxf from A9CAD, use version 12 or older .dxf's

[sploo]

Originally Posted by ger21 When you save the .dxf from A9CAD, use version 12 or older .dxf's

I'm afraid I can't find any option to choose the DXF save version (either in the file save dialog, or from the menus). A quick check of the help docs hasn't unveiled anything either.

Is it a feature only present on the Pro version?

[ger21]

You're right, it doesn't have it. Try downloading their A9 converter and see if converting it makes a difference?

[ger21]

Also, could you post the problem .dxf here, and let me look at it?

[sploo]

Originally Posted by ger21 You're right, it doesn't have it. Try downloading their A9 converter and see if converting it makes a difference?

I've used A9Convertor and converted the file to an AutoCAD 12 DXF - which has resulted in a smaller file.

I'm not sure if I'll get chance to test it on SheetCAM tonight, but I'll let you know the results when I've tried.

I can post the original file, but it's literally:

1) Open A9CAD (v2.2.1)
2) Draw a rectangle
3) Draw two circles inside the rectangle
4) Save as DXF

[ger21]

If that doesn't help, try exploding the objects before saving.

[sploo]

Doh!

Gerry, my apologies, I've been wasting your time.

I took another look at the drawing I'd been using (just a quick and dirty 'slap some shapes down to see what happens').

It's rather hard to cut a 20x10mm rectangle with two <4mm diameter holes when you've setup the CAM program to use a 1/4" (6.35mm) tool!

I put together something on a more sensible scale; SheetCAM then produces a set of paths and rapids that look fine, and the resulting g-code runs as I'd expect on both CNCSimulator and Mach.

This looks exactly like what I need, but I'll see if I can get an eval licence for SheetCAM (as the 150 line limit is a bit restrictive). That way I can have a play before I get a machine, but it certainly looks promising.

Many thanks for your help!