I seem to not be using my CNC bits correctly or I had two faulty bits, I'm not quite sure. Either way I need some expert advise for what I should do in order to avoid breaking bits. I'll give you a run down of what I am doing...
I've had two bits break in the past 3-4 weeks. I purchased two Precise Bits end mill bits (MM208-1250-113FL, 0.1250in dia. 2-flute DeepReach carbide 28.88 57.76 end mill, fish-tail tip, 1.125in DOC, 3in OAL , 1/8in shank). I make 2D kids toys out of poplar wood. I make about 200 different ones. You can see my work at Handmade Wooden Toys - Wood Toys - Waldorf Toys - Kids Toys. The bits were recommended to me by Precise Bits over the phone before I ordered them after I explained to them what I would be using my CNC machine for.
The only cutting I am doing is 2D profile cutting. The wood I am using is .8125 inch thick poplar. I am cutting in two profile cuts. The first profile cutting depth is .9 inch, with .1 inch passes (so 9 passes for the profile), and with an "allowance offset" of .05 inch and .2 inch thick & .2 inch wide tabs evenly placed around the cutouts. The first profile feed rate is 25 ipm with a plunge rate of 10 ipm. The second profile cutting depth is .9 inch with a single .9 inch pass, with an allowance offset of 0.0, and with .2 inch thick & .2 inch wide tabs evenly placed around the cutouts. The second profile feed rate is 10 ipm with a plunge rate of 5 ipm. The second profile basically shaves the sides of the cut outs to remove the 9 lines left in the side of the cut outs from the first profile cut passes. For all of my cutting I am using "climb" cutting. My router is a DeWalt DWP 611 (16,000-27,000 rpm with adjustable speed) and it runs on setting "5" (speed is controlled in numbers of 1-6) when I am cutting, which I am guessing is around 22500 rpm.
I have ordered two more MM208-1250-113FL bits that are scheduled to arrive to me tomorrow (9/26). Before I begin cutting more stock I would like to resolve this issue as I am now increasing the amount of cutting I am doing with my CNC and I don't want to be breaking a bit once a week. What am I doing wrong? Am I using the right bits? Should I adjust the feed rates or plunge rates? Perhaps .1 inch is to deep for the passes? Is .05 inch too much to be shaving off the sides of the cut outs in one .9 inch deep pass? I'm just not sure what to adjust and need some expert advise.
Thank you very much for any and all help!!!
Dustin