Hi all,
I was cutting a pocket 75mm x 25mm on a 1" poplar board using 1/4" spiral down cut endmill (#251). Using 18000 rpm, 1900 mm/min feed rate and a DOC 2.5mm. The cutter was producing bands of wood rather than chips. Tried changing speed and feed rate up and down in the range 12000-20000 rpm and feed rates 1200-2200. result was the same. Any suggestions on how I can get it to get better chip load?
I have the 80mm spindle.
Thanks,
Mani
That’s a chipload of about 0.002" (0.05mm), you want closer to 0.010" (0.25mm).
Your slowest spindle speed is 8000, and with a feedrate of 150 ipm (~3750 mmpm), that’s a chipload of 0.009" (0.23mm)
How deep is the pocket? And why use a downcut? If you’re trying to avoid chipping/fraying, use the downcut on the first pass, then an upcut on the rest. Or rough it out to 0.010" (0.25mm) stock on walls, then downcut the finish pass on the walls. (Climb cut!)
Poplar is stringy wood by nature. I had a project where I had to cut into a block of it and the strings coming off the cutting bit literally clogged my dust collection at the first elbow.
Thanks. The pocket is through the thickness - 1".
I used the down cut thinking the 251 cutter would work better than the 201 which is a flat endmill I believe is upcut.
I will try with a spiral compression cutter I have to see if any better. I will try the numbers you recommended to see if things improve. Thanks
The #251 only has a cutting flute length of
Cutting Length 0.75 in
So please don’t try a full-depth finishing pass.
I suspect you’ll have better luck with a tool which has a cutting flute length which matches the cut which you are making.
I would slow the spindle to 12,000-14,000rpm and set 2500mm/min feed and try that to help your chip load right at 0.003-0.004
I also personally prefer upcut, I can sand the little bit of top of the surface if there is fraying
A possible solution for this might be:
which are router bits with a chipbreaker feature — note that the success of this will depend on the depth per pass and how that interacts with where on the flute geometry the chipbreaker notch is.
I never saw a chip breaker bits for wood. That might help on stringy red oak.
Thanks !
Thanks Will. What would recommend as depth per pass. I was doing 1.5-3 mm as the diameter was 1/4" (6.3mm)
Thanks
I just use the defaults in Carbide Create.
For working out other options see:
I haven’t used these chipbreaker bits, but can heartily recommend the similar Beast and the Badger bits from IDC Woodcraft. I use them frequently on hardwoods and they’re amazing - you can remove material at rates you never would have thought possible, and they mostly eliminate the splintering you’re seeing.
Mike
Another one I did not know about. Thanks
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