Mixed results cutting aluminum sheet

[denver]

Hello,

Using the following I've gotten very good results cutting 9" disks from 0.050" aluminum:
Onsrud 64-018 3/16" downcut O flute
Two passes, both 0.065" deep, with a 1" ramp
First pass 0.7 IPS at 11000 RPM, climb, with 0.020" offset
Second pass 1.0 IPS at 13000 RPM, climb, no offset
I'm using a vacuum puck with All Star gasket to hold the material. The edges of the parts are very clean and smooth.

If I change to a 64-025 1/4" downcut O flute, I get edges that have curled under burrs. Both bits are brand new. I'm having trouble figuring out why the 3/16" works so well, and the 1/4" so poorly. Anybody have any ideas?

Thanks,

Denver

[dlcw]

Denver,

I would guess it has to do with spindle speed and feed rate. Each bit will need to be fine tuned to find the perfect sweet spot. I had to do this with different sized compression bits on plywood.

[denver]

Thanks Don. Actually, the bit wasn't as new as I thought, and it had a small nick in the end. I replaced it and everything is cutting smoothly again.

Thanks,

Denver

[Big-Tex]

I cut .064 alum. with 2 flute upspiral 1/4" at 8000rpm at 5in per min all one pass no tool wear.

[joe]

I'm with Thomas on this one.

I've cut hundred's of letters using a 1/4" Belin, up sprial, O flute without any fluids. The cutting speed and RPMS depends on which aluminum.

I like using the 3D tab function. A quick twist of each letter and they fall out and are ready for the bench sander. This materials sands like a dream.

All that said, I have learned I can purchase the letters cut with a water jet as cheaply as I can buy the aluminum and cut it myself. A water cut letter is better.

Joe
www.normansignco.com (http://www.normansignco.com)