On this page I'm largely going to record my experiences with my CAD/CAM/CNC software and my Tree CNC knee mill.
I have copies of Intergraph SmartSketch (2D CAD), and Rhino3D and Alibre for 3D CAD/surfacing/modeling. My CAM software is MecSoft's VisualMill (VM). I've retrofitted my Journeyman 325 Tree mill with a Centroid 4 axis control with most all of the softwared options, including digitizing/probing and a 4th axis.
Here's my first major CNC project . This is a stamp that will be heated and used to imprint a foam product. I did the design in Rhino3D. It wasn't hard, but it was time consuming as the text tool leaves the text kerned tightly, which doesn't leave room between small letters to get a tiny endmill in to machine them. I got around this by doing each line of text, then turning on "ortho" so things would stay in line. Since I was going to use a 1/16" end mill I drew a .070" circle, and dragged that between all the letters. Where there was insufficient room I'd scoot the letters apart. I've suggested to both the Rhino and VM folks that they enhance the text tool to allow the spacing between letters to be adjusted. Since that can be done in my 10 year old copy of MS Word, it seems like it should be possible to add to this other software. The letters stand .100" above the base surface, and are about .080" wide on the "stroke".
It turns out that the Centroid post processor in VisualMill is pretty basic, and it output arcs as short line segments instead of taking advantage of the arc functions available in the control. I've got someone who is going to help me figure out how to modify the post processor to use the full capabilites of the Centroid control. At least Visual Mill comes with a post-processor generator program, so I'm not stuck having to buy a custom post from someone - presuming I can figure out how to correctly code things in the generator.
I'd never used a 1/16" end mill before, so I was pretty cautious. I ended up running at 5200 RPM (I've not quite gotten the spindle drive sorted out on the Tree, which should have a maximum of 6000 RPM available), .050" depth of cut in full-width slotting, with a 2.4 IPM feed. I think that might be bumped up a little, but I didn't want to break a lot of end mills experimenting. For these small cutters a high-speed sub-spindle or spindle speeder would be very nice to have. At 5200 RPM the carbide EM is running at about 10-15% of the recommended speed, and you can't feed it very quickly.
© 1996-2006 Michael Moore, last update for this page 11 August 2006
http://www.eurospares.com/cnc.htm
