I never did until today! Don't think I'll be making any more soon, either! This was tool work, not laser...

One of my customer's engineers asked me last week if I could make some ornaments out of some large 350x450mm PCB's they had to destroy? --He asked me "is this even possible with 1.6mm FR4+copper?"

Oh, I don't see why not! ... but it didn't take me long to figure out why he asked that question...

What he wanted was for me to turn this:

PCB.jpg


into THIS. He even sent me the vector file, it was laid out perfect to miss all the large mounting holes...

pcb2.jpg pcb3.jpg

As you can see, I did get the job done, but wow...

I put the plate on my trusty IS7000, set my 3-flute Garr 1/16" endmill to the correct depth, and proceeded to drill the hanger holes.
No problem. Let's try a tree...

No problem! Cut nicely-- Let's try another one...

Halfway thru the second tree, the copper started mushing up the edges of the cut, and I noticed the spindle was rising up--
I stop the machine, and the endmill was so dull already that it wouldn't cut the copper, and the lower layer of copper was
balling up... Well, that endmill had about about 50 hours of cutting holes in black anodized aluminum on it, so I grab a new
2-flute endmill...

It cut the first tree dandy. About 2/3 thru the second tree, it got so dull that it wouldn't cut as fast as the machine was
pushing it, and it snapped in half...

It was then that I looked up "FR4 PCB"... 8 layers of fiberglass with 2 layers of copper top & bottom. That might explain it!

So to finish this job I ended up cutting them out with a standard engraving tool, with a 12° angle and a .020" or so tip.
I could only go .015" deep at a time, and 8 trees was about it before having to sharpen the tool.

I've never seen anything dull a carbide tool like this stuff did! The tool wear was probably at least 2x the wear I get cutting the
same linear inches of stainless steel!

Each pass took 45 seconds from tree to tree, 4 passes each tree = 3 minutes each, x30 trees = 90 minutes pure machine time...
plus around 10 tool sharpenings, add at least another half hour, plus deburring, plus two $9 endmills...

They turned out really nice, but I'm not sure I want to mess with cutting this stuff again!