I’ve found that upcut bits will tend to pull up then materials, like 1/8" stock. I just cut some parts out of .118" acrylic and decided that next time I should make multiple passes to help keep it from climbing the bit on a full-depth cut.

Downcut bits have a much harder time removing the dust and shavings from the cut path, so it’s a bad idea to use them on materials like aluminum and acrylic where re-cutting the shaving will cause increased friction and melt the material to the bit.

that is definitely good to know, i just had my machine delivered so i am gonna see what bits came with it and if i need to buy a upcut bit, homedepot here i come

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That’s what I’ve read. I tested the straight flute and the upcut bits on the acrylic and the straight cut consistently clogged up and melted the acrylic to the bit.

I am new to the CNC world, but I have a lot of woodworking skills. I am a guitar builder and in my process of building I use 1/4" spiral bits. Sometimes I use a Upcut bit and sometimes a downcut bit. Typically I use a down cut bit when I need an edge that is smooth (typical with inlays). But when I am removing material from deeper pockets I use an Upcut bit. Typically I would choose an Upcut spiral bit when roughing and use a downcut bit for detail work. Are there any concerns that I should be aware of while using a downcut spiral bit on a CNC?

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