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Robin Hewitt
18-09-2009, 10:42 PM
I got that cheap Alibre for $99 3d drawing package, but the freeby CAM is a bit naff, only does parallel lines, much too steppy, want to cut watermarks. Been looking for software that does that, doesn't seem to be there :nope:

So I emailed my brother, gave him a stinky stl file and pointed him at Wikipedia where stl is explained.

Took him approx 3/4 hour to read the file, put it on screen as a wireframe and let me turn it in all 3 planes.

He's gone away to shade it so it will look solider.

He says toolpaths are dead easy, ball nose not a problem, anti-collision easy, it's 'only' vectors. Basically I can have what I like :eek:

So any ideas what I should ask for? What do the big boys do that is so freaking miraculous?:heehee:

I want to cut injection tooling in 7075 T6 alloy.

irving2008
18-09-2009, 10:53 PM
I got that cheap Alibre for $99 3d drawing package, but the freeby CAM is a bit naff, only does parallel lines, much too steppy, want to cut watermarks. Been looking for software that does that, doesn't seem to be there :nope:

So I emailed my brother, gave him a stinky stl file and pointed him at Wikipedia where stl is explained.

Took him approx 3/4 hour to read the file, put it on screen as a wireframe and let me turn it in all 3 planes.

He's gone away to shade it so it will look solider.

He says toolpaths are dead easy, ball nose not a problem, anti-collision easy, it's 'only' vectors. Basically I can have what I like :eek:

So any ideas what I should ask for? What do the big boys do that is so freaking miraculous?:heehee:

I want to cut injection tooling in 7075 T6 alloy.

Sounds like a good step forward...

So he's doing STL to G-Code?

I'm assuming he's figured out inside v outside for the toolpaths?

Feed rate/DOC/Spindle revs for given tool type/# flutes/workpiece material/chip loading?

Tool change points?

Robin Hewitt
18-09-2009, 11:40 PM
I'm assuming he's figured out inside v outside for the toolpaths?

Apparently you get that from the facet normal command which preceeds the facet or something like that, he did explain but it's a few nautical miles above my head.

I think spiral roughing with a depth increment, CW round lumps, CCW round pockets is a good idea?

Watermarks for finishing upright faces, flat nose cutter for finishing horizontals and something clever in the corners where they don't quite meet up.

Output as something a bit more compact than G-code perhaps, maybe I should let him talk to the steppers?

irving2008
18-09-2009, 11:48 PM
Apparently you get that from the facet normal command which preceeds the facet or something like that, he did explain but it's a few nautical miles above my head.

I think spiral roughing with a depth increment, CW round lumps, CCW round pockets is a good idea?

Watermarks for finishing upright faces, flat nose cutter for finishing horizontals and something clever in the corners where they don't quite meet up.

Output as something a bit more compact than G-code perhaps, maybe I should let him talk to the steppers?

Yes, every surface in STL is made up of triangles whose edges rotate clockwise round the external perpendicular to the surface, so the order of the edges determines where inside and outside are...

talking direct to steppers isnt a good idea, IMHO, unless he replicates a lot of the capability of Mach3, e.g. acceleration control, limits, homing, etc...

tribbles
19-09-2009, 01:22 AM
I've developed my own software for converting STL to GCode (hence the name of my milling machine - STLCutter).

It's not too difficult; my challenge was that I needed a large object cut up into a number of blocks, and each block is cut individually.

I've also written a number of algorithms that are designed to give different qualities of cut depending on the complexity of the object being cut.

For example, the original algorithm would do a scale model cut of the car I'm building in just over 2 hours - a new algorithm which is more suited to smooth objects has cut this to 28 minutes. There's one other algorithm which I'd like to get working, but it's a very complex algorithm to work out.

The accuracy I've put into it isn't terribly high (1mm), but it's just numbers to the computer - higher resolutions can be easily created.

If your brother wants to contact me, send me a PM - I can give some help if he needs it.

The only slight thing is that I've done my software in Mac OS (with Objective-C), since it's my main platform (at home) for development. However, it originated in standard C on a BSD box.