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Discussion Starter · #1 ·
Hi all, hope you experienced CNCers can advise me. Surfacing a slab of maple, using the Amana 45525 bit. Running it at the recommended speed of 18000, and cutting at 100ips (the fastest my machine will go), with a depth of cut of 0.5mm, I just get continual burning.
Tried slowing the rpm - no difference. Different step-overs - no difference. The bit has only surfaced 2 MDF spoilboards, and a couple of other (not maple) slabs, so I can't believe it's blunt already. Cutting with a 1/2 inch router bit the surface was perfect. Is maple particularly hard on bits? Any advice appreciated.
 

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it was likely the mdf that dulled your bit, if anything imho. you may slow the rpms down to 10k or so and try it, since that is a 3 flute. burning means cutter is dull or spinning "too fast", or feed rate is too slow. since you can't feed faster, you have to slow down the rpm's.
 

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Do you mean inches per minute? 100 inches per second is flying. What is your machine? The pic looks like you may have a tramming issue, too. Does the material have ridges or is it just that the burning makes it look that way in the pic?
 

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David - Machinist in wood
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I agree that you may have a tramming issue. I use a two-flute flat bottom bit to surface my spoilboard at 400ipm (18k rpm). Something like the Maple you've shown I would probably surface at 200ipm to 250ipm.
 

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Discussion Starter · #5 ·
Thanks for your replies. I did try slowing the rpm down to 10K at which point the router was stalling, but no difference. Yes, of course I meant inches per minute! The system was tramming previously, but I fixed that and the surface is now completely smooth to the touch - the main scorch marks are on the point where the bit is making the cut. As it surfaces perfectly with a 1/2 inch router bit I am inclined to think that the Amana bit has dulled, which for an expensive bit is disappointing, after just 4 uses. My Machine is an Oozenest WorkBee. Max speed is 2500 mm/min, which equates to 98 ipm, so I am thinking that this is just the wrong bit to use with this machine, however running at 15000 rpm and 98 ipm would give the same chipload to that recommended.
 

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fwiw the chip load calculator i use from US Router Tools suggests 855-945 ipm at 15k rpm's, 3 flute on hardwoods (0.02 chip load)
you may also try a lighter cut at a lower rpm...

if you have tried all of the recommendations and still burning, your bit is likely dull...
 
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