Smoking wood...Hard Maple

[Kirk Quesnelle]

Hey guys,

I'm new to CNC. I have an Axiom AR8 machine. I am using an Amana Spiral Flute Down-cut Plunge 1/4" (46415) to cut into HARD maple.
I am making ring boxes. (see attached photo to get a better idea)

PROBLEM: I am seeing smoke and a bit of a screeching sound.

However, this only happens when I'm doing the profile cut. It doesn't seem to have a problem and the bit doesn't heat up
when doing the pocket. I haven't setup my dust collection, and because it's a downcut, maybe the chips are getting caught ?

I am about 100 IPM, 18,000 RPM and I've tried to do really really small passes and it still happens.

What do you guys think?




Thanks a lot

[Jerome Stanek]

On a profile cut you are packing the kerf with saw dust with a down cut.

[Mick Simon]

Is it doing it on all the profile passes or just the last one(s)? Almost sounds like you're past the flute length of the bit and rubbing the shank.

[Robert L Stewart]

I started with down cutting bits. Soon realized that up cutting was the only way to go. Even in difficult veneer like Zebrano or Sapele they still
work by adjusting the depth of the first few passes. Another issue is usually dull bits. Also what Mick S. said.

[Kirk Quesnelle]

Thanks guys,

I'm not sure if it's a dull bit or not because I don't have enough experience to know just yet. It's a carbide amana tool. I've done about 10 MDF cutouts with it that are about
2'x1'. I've never overheated the bit. I always would check it after doing work with MDF and it was hardly luke warm. My assumption is that it is still really sharp. I mean it feels sharp
and it doesn't have any trouble cutting the pocket. No smoke, and really smooth finish.


Robert, I think you're right about the profile and downcut bit. As soon as I start the first profile pass I can see a bit of smoke. And I guess because there isn't any compression
with the pocket, is why it does the pocket perfectly.

I will try today with dust collection and see if it still happens


Other than that, do you guys recommend any kind of up spiral upcut bit ?

(I need to be able to profile at least 1")

[David Falkner]

I use downcut bits all the time, 1/4" and 1/8", and in cutting Maple, Cherry, and Walnut I've never seen smoke or heard any screeching. Most everything I do is 18k rpm and 75 ipm on the 1/8" with 100-150 ipm on the 1/4" bit. I do pockets, contours, profiles, etc. and have yet to see an issue. I'm using Freud and Whiteside for these bits.

David

[Kirk Quesnelle]

Hmmm.. I wonder if my bit is dull. I don't think that's the case, but if it is.. holy smokes these bits don't last long
because I've only done 10, 15 MDF cutouts. Perhaps the ring boxes out of hard maple won't be feasible

I'll try a few more things, including some of the brands of bits you suggested

Thanks David!

[Mick Simon]

Downcut spirals will almost always dull more quickly than upcut due to inferior chip ejection. The workaround is shallower passes at higher feedrates. It's the chips that carry the heat away from the cutting edge. Downcut bits force the chips (and heat) into the cut rather than pulling them out the way upcuts bits do. Heat is the number one reason for dulling bits. For MDF, plywood and composites in particular, I greatly prefer compression spirals.

I think this is a very good primer for proper tooling choices for those new to CNC.