I think the bit snapped because of heat, feed was too slow. I bet you can run a deeper 10mm cut with same feed used in the 6mm one. You should do the test always using same feed but going deeper on each test. Slowing the feed and increasing depth doesn't give you any advantage in cycle time. Subscribed 👌🏻
I think part of the problem is also that even with a VFD spindle, the machine has other shortfalls. The lack of linear rails allows for too much flex. Fortunately, that will be remedied very soon. I should be getting my new CNC (Shapeoko Pro 5 4x2) very soon. Then I will rerun this test. Thanks for watching!
How much did you set for rest machining? I guess you could do the 10mm, if you set the rest machning lower, so that the v bit doesnt have to work that hard.. Also do a helical /ramp downcut instead of plunge would help with chip clearance.. Also an upcut bit would help a lot on the chip clearance, and as you're doing a v bit clearance afterwards, i guess an upcut bit could be used for the roughing.. But fun to see how it all works..
I have not tested doing ramping into a vcarve before. I might give that a try. As for the rest of the machining, all speeds and feeds were identical for the 1/8 inch bit, and the tapered ballnose. I will likely switch back to upcut bits for clearing so long as I don't start seeing tear-out. I chose to carve stars, because I knew that the tapered ballnose would have to do some serious work to get the sharp corners and would provide for a good test of the strength of the bit. My last carve, I did a fairly intricate edge-grain vcarve at 4mm DOC and 600mm/min speeds at 18200 RPM. Thanks for watching!
It didn't look like to me that you ever achieved the feed speeds you were expecting. Unless you have your accelerate and decelerate speeds set extremely fast those short moves will always be slower than what you had programed for. I recently carved something and had the speed set to 100 IPM watching the software I never saw anything faster than 57 IPM. Short moves means slower feed rates regardless what you have it programed for. I did enjoy the video.
I had hoped to get up to 10mm D.O.C at 250mm/Min, but the ballnose bit I use didn't survive. I believe it is a limitation of the machine, as it has neither ball screws or linear rails, and may have just a bit too much flex in the axis to move. I have been using a D.O.C of 2mm at a rate of 600mm/min. I was honestly surprised that I hit 10mm D.O.C at any speed. That seems very high for a hobby CNC. I am happy you enjoyed the video. Thanks for watching!
