Any idea of the cause of this fuzziness on my cut

[TTalma]

I was milling some hard maple last night and the sides with the grain were all fuzzy when I was done (See pic) end grain was nice and smooth.

My machine was set as following:

1/4" upcut 2 flute spiral bit. 1" long cutter face
100ipm
cut depth .25"
climb cut
21000 rpms

Any idea what caused this?



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[ger21]

The grain, and the climb cut. A brand new bit will help, but conventional cutting will almost always give a cleaner cut in wood.

[wizard]

Note the direction of the grain. A very sharp too and going in the right direction will help. Hard maple can be very difficult at times.

The other possible suggestion here is to check on a luthiers web site as they often work with maple electric guitar bodies. They may have other suggestions but the few times I've worked with maple I found that tear out was a big problem. The only things that really helped is very sharp tools going in the right direction. In some cases I had to resort to a significant amount of sanding.

[fretman_2]

I've not cut hundreds of maple guitar bodies and necks, but I have cut some and have not seen that. Generally, the upcut bits make cuts that are a bit more raggedy. Try a downcut bit and see if you have those problems.

[TTalma]

Thanks for the help. Tried each of your suggestions in turn.

The first thing I did was try a different bit. And I think this was the problem as it almost immediately got better. the bit still feels sharp. I did not have another upcut to compare to but tried new straight flute, and downcut bits. Both had much better results, only need a light sanding. almost all fuzziness was gone.

Playing around with the settings I got the best results with
1/4" straight bit 100ipm
cut depth .25
conventional cut
18000 rpm.

Although I did not notice much difference in surface quality between climb cut and conventional cut. I looked a little online and could only find that climb in metal can help prolong the life of the tool by putting more heat in the chip. Is there any effect for cutting in wood? I will be doing almost all my cutting in wood and would like to prolong the bit life as much as I can.

[ger21]

From my experience, climb cutting in wood almost always results in a poorer finish, and shorter tool life.

The only time I climb cut is when cutting along the edge of a board, where tearout would be likely to occur with a conventional cut.

If you want longer tool life, drop your rpm to 10,000-12,000 at 100ipm.
For maximum tool life in wood, you want the maximum feedrate at the minimum rpm. Maximum tool life, however, will not usually result in the best finish, so you have to compromise. So cut as fast as you can, as long as the finish is still acceptable.

If I'm cutting hardwoods, I'll do a rough cut leaving .015", at about 300-350ipm and 17,000 rpm, then clean up that .015" with a finish pass at 150-200ipm.
Of course your machine's capabilities have an effect on this as well.

[wizard]

Thanks for the help. Tried each of your suggestions in turn.

The first thing I did was try a different bit. And I think this was the problem as it almost immediately got better. the bit still feels sharp. I did not have another upcut to compare to but tried new straight flute, and downcut bits. Both had much better results, only need a light sanding. almost all fuzziness was gone.

Playing around with the settings I got the best results with
1/4" straight bit 100ipm
cut depth .25
conventional cut
18000 rpm.

Although I did not notice much difference in surface quality between climb cut and conventional cut. I looked a little online and could only find that climb in metal can help prolong the life of the tool by putting more heat in the chip. Is there any effect for cutting in wood? I will be doing almost all my cutting in wood and would like to prolong the bit life as much as I can.

With some woods it isn't so much a issue of climb or conventional milling as it is going with or against the grain. This isn't just an issue with CNC equipment as I've had similar tear out in maple running it through a planer. Simply end for end the board and you have a much cleaner surface without the bits and nasties of tear out.

Oh the other thing here is the sharp tool, it makes a huge difference. The geometry of the tool can help too. There are a lot of factors that ultimately come into play. You can have a board that machines beautifully for 90% of its length and then get into some ugly grain that just doesn't want to cooperate with cutting tools.

[ger21]

If you make your cuts with a conventional cut, so that there is wood on both sides of the tool, it's virtually impossible to get tearout.