Hi all,
Looking for some help on solving an issue with burn marks.
I’m using a 32mm, 2 flute surfacing bit.
The last cut I ran was at 80ipm and about 13k rpm - on a hardwood (not sure of the type).
Any help or tips in this regard would be appreciated!
Slow down the router so you get chips instead of dust.
If that still doesn’t do it… Bit may be dull
Hi Kyle - the OF only works with bits measured in imperial inches. JKJK 
What is your depth of cut? 80ipm seems reasonable, though I do use 100ipm when surfacing. My Makita is set on “2” for speed - that should be in the 12K range.
Given all that, BJ might be correct - how old is the bit?
-Tom
Precise bits guy told me 10,000 RPM and 170 IPM for a 1" surfacing bit…
1.25 Amana Surfacing bit. 140ipm. 02 depth, makita set to 2 or a bit slower.
I was told burn marks with surfacing bits indicate too low ipm, maybe tweek the speed up closer to ones listed in above replys
Burn marks should be from the bit rubbing on the wood.
Thanks for all the useful help! I brought the feed rate up to 100ipm and slowed the RPM down to just under Makita “2” and it seemed to like that a whole lot better.
Will a similar approach work for a larger (32mm) 90 deg V-bit as well? I was trying to cut 12mm plywood - all the way through to create 45 deg chamfers, but my cut came out skew and pretty uneven. There was a lot of noise and chatter on the cut, so wondering what you all suggest here for feed and speed rates??
Trying to do a 12mm cut in Birch Plywood
The amount of chip removal per revolution determines the temperature of the bit and wood. The bit transfers its heat into the chips as it removes them. If the chip size is not large enough the heat will stay in the bit and heats the bit. If the bit is not moving fast enough across the material then it is not able to take a large enough bite into the wood to take a chip and instead rubs the wood and then heats the wood up.
The larger the bit the less rpms you can use due to vibration of the bits mass.
The best advice is to get a chip removal chart for the material you are cutting and dial in the speeds for the bits you are using to see what chip load you have. This will eliminate burning of the wood and keep your bits sharper longer.
At 13000rpm 2flute 12mm should be around 130ipm for plywood.