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Machining fence pickets7/26/14
I am machining the tops of these pickets to match existing in 3/4" x 2-1/2" white pine. Having trouble with splitting at this point using a 3/8" 2 flute downcutting spiral bit, 17000 rpm counterclockwise cut. Tried one and 2 passes, same result. Any suggestions? I am making a jig that will machine 12 at a time but need some suggestions on tooling, rpm and feed direction. Thanks for your help.
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I would suggest cutting clockwise around these plus an up cut bit will be less likely to split. You may find you want to offset the 1st part away from the finished edge by .02" then for the final pass cut in a counter clockwise direction.
Also, use a chip breaker or roughing tool if you can.
You may end up doing this in 2 operations, not once around the part.
I'm guessing Allen is Skillet LOL
Well I think I've got it working. Took both of your advice plus tweaked things a little on this end. Ended up using a 3/8" high shear bit for a counterclockwise pass at the top and a clockwise pass at the bottom, bottom pass .02" larger than final dimension. Second pass with 1/4" down cut at final dimension in a counterclockwise pass. Seems to be working, got 11 out of 12 on my first run through, one got a little loose but can fix that. Thanks for the input gents! Now to get 300 more done.