Gator Board

[dengler]

I am having trouble routing Gator Board (foam core with paper face) and I was wondering if anyone had some tips for me.

Just some back ground. . These are 10" tall letters that need a smooth edge. My current edge looks like lava rock at times. Some times it is awesome and other times it pulls like crazy.
I am using a (sharp) Onsrud 60-241 to cut with at this time. This is a low helix 3 flute up cut bit. My feed is 236 IPM @ 16000 RPM.

Does anyone have any advise for me?

[bleeth]

It's the up cut part that is causing the issue. With the paper face you should try either a straight or down cutter. slow spin and fast moving so you don't overheat the foam.

[dengler]

Dave.
It is not the face that is giving me the issues. It is the foam. It looks like it may be overheating. Do you run a certain speed/rpm when you cut foam?

[bleeth]

Dan:
The bit you are using is designed for hard materials like solid phenolic or fiberglass. Check Onsruds catolog on line and you will see several bit series designed for foam. You don't say what machine you are using but at that speed I will assume a PRS Alpha or standard. The speed should be fine but I would cut down on the RPM's and use a different bit. Foam cuts fine for me at 8K. I am a fan of O flutes for plastic.
Here is a link to the catalog. Look on page 8 for soft plastic bits.

http://www.onsrud.com/files/pdf/OC-09CatalogR.pdf

[dengler]

Dave,
The 3 flute cutter was a suggestion from Brady, and it does give a good cut at times, but it is not consistent enough for us.
But as for machines I am using a PRT and a Biesse Rover 322 (400IPM).

[dengler]

I have used the O's and Super O's as well with a similar edge quality.

[bleeth]

Dan:

Have you tried dialing down your RPM's yet?
I cut hard plastic with a 1 flute at 12 k although a slower feed. 3 flutes at 16k is way too much contact. Hence the heat.