Compression bit on 1/2 inch Birch Finish Ply

[ChrisR]

Centurion is telling us we should be getting a weeks worth of cutting with the designs (monograms) we are doing on the bits but when I alter the settings the edges have a lot more to clean. Running at full depth I was running it at 12k RPM, 1.5 IPS and getting nice clean edges but also leaving a mostly powdery sawdust behind. I've tried increasing IPS and/or decreasing RPM so it's more of a 'chip' and also tried using a few different chipload references and it's telling me I should be running between 2-8 IPS? At the old settings the bit sounds good and only screams a bit at corners (which unfortunately there are a lot of) and didn't leave burn marks.

I know a lot of this I should of figured out on my own but where I'm working on this, the higher-ups decided to run a sale on things before I had everything 100% figured out.

Also is there a way of determining how many inches are in a cut? I've searched a bit on here and google and haven't come up with much.

[dlcw]

Hi Chris,

Welcome to the board.

When I cut BB, I use a 1/4" compression bit in two passes. First pass is a climb cut and I leave a 1/32" skin. I then do a conventional cut cutting through the skin. I run at 11K rpm at 6IPS feedrate. Most of my cutting is straight line so the machine can get up to speed. If you are doing parts with lots of curves and the machine can't get up to speed, then I would probably set my speed around 4IPS.

I can take parts off the CNC directly to the edgebander doing nothing but cleaning the sawdust off. The cuts are clean and smooth.

[ChrisR]

Thanks for the reply,

Most of the work they have me doing involves a lot of curves, it's mostly scrollwork style letter cut-outs. I had it up around 3.5 IPS and things started to get charred on corners. I tried increasing and decreasing RPS between 10k to 14k and nothing much else seemed to help. Got a nice burn mark almost through the spoilboard now because of it. I'll try one like how you suggested in a bit and see how it comes out. When I do climb on this wood though, it's "bad" edge is the one on the wood we want to keep so I do most of mine in conventional.

[ChrisR]

Ok so we got it running good, 6 IPS @ 10500 RPM seems to be the "sweet-spot" for the wood they chose to use. Thanks for your advice. I had to alter my way of thinking because in my mind, slow speed meant cleaner edges but I'm also not a wood craftsman like most people on here and where as I already respected anyone who works with wood, the level has risen 3x. Where I work I'm used to using lasers and metal engravers where each piece is exactly the same as the last, but with wood each sheet can be it's own beast. Also doesn't help that I usually tend to be over cautious, but with what I'm used to using you can just go over it again and if something goes wrong it's cheaper than a broken bit and chewed up wood hehe.