Recently upgraded from a router to an 80mm Redline spindle on my Onefinity. I’m assuming I’m having speeds and feeds or spindle speed issues, but every cut I’ve done has terrible burning. The picture below is .8 inch cherry. It was cut using a new Spectra 1/8 in bit. Cut was running at 75 ipm and .05 depth of cut. I’m getting the same results in walnut, while maple scorched the edge but didn’t leave the caked on burnt mess like in the image here. Same results running a 1/4 compression bit.
Is that a carbide bit or high speed steel?
I bought one from Amazon that was supposed to be carbide and it turned out to be high speed steel which burn very quickly if you are cutting too slow.
What is the speed setting?
I also noticed the cherry had some worm holes
Any chance the wood had dirt in it that may have dulled the carbide?
If under magnification you see a shiny cutting edge then it’s dulled
With a compression bit you need to cut much deeper than normal to get any advantage. Exact depth depends on your bit, but usually a 0.25 or 0.375 to engage both up and down cutters.
I think 22K is far too fast for cherry - I used 14K-16K at 80ipm and DOC is usually 0.1”. Can go faster with shallower DOC - limited based on the power of the PwnCNC spindle. I used to run the Makita at 2.5 on the dial, 120ipm @ DOC=0.15” or DOC=0.25” at 80ipm for a 1/4” end mill.
All that said, is the bit spinning the proper direction? I mean that would simply turn a climb cut into a conventional cut, right? Shouldn’t cause burning like that.
If the bit is turning in the wrong direction it would not cut at all. I cut a lot of cherry and it does burn easy, I run at 150 inches a minute and it works good for me with RPM anywhere between 2K and 18K.
Final solution: Somehow my Redline spindle switched motor direction since the initial setup. After close inspection I realized the spindle was turning the bit backwards. Now, how did it actually manage to make that profile cut in a piece of cherry while spinning the wrong direction? It was rubbing its way through the wood instead of cutting.
