Date: Wed, 12 Nov 2003 13:00:28 -0500
From: David LoBosco
To: mas863
Subject: Modela Tips
In order to add to the growing base of knowledge on the Modela, here are a few things I discovered last night.
One of the main problems I was having was that my traces were too thin and actually disappeared in certain areas. I solved this by changing my wire thickness to .020" in Eagle, using a -.004" undercut (an overcut) in cam.py, and using a .010" end mill.
The .010" end mills make much nicer cuts than the .015" ones but tend to brake much more often and completely (the tip snaps off). I was able to extend the life of the .010" end mills by milling at a smaller depth z down= -.007" rather than -.015".
This lengthened the life of the mill but it still broke when it was about 60% done with the rastering. I didn't want to run the whole milling job again so I opened up the .rml file in notepad to see if I could just start the job from the point where the mill broke. The .rml file is basically a series of x,y coordinates in the same format as the move.rml. With a couple moves using move.rml I figured out the coordinates where the mill broke so that I could delete all the commands in out.rml that occur before this part of the rastering. I saved it as a new name, replaced the end mill and started the new job. It picked up at the right spot and saved me a lot of time.
To recap, these settings worked fairly well on my 20 mil wire traces. Tool diameter: 0.010. Countour Undercut: -0.004. Raster Overlap: 0.65 (as long as the end mill isn't worn out). Z up: 0.04. Z down: -0.007. XY speed: 2. Z speed: 5.
-Dave