Okay so for some reason I have broken two 1/8” endmills back to back. A 2 flute Straight endmill and a compression endmill. I am trying to make some of those wooden jack-o-lanterns. It does fun for instance on the nose. Cuts the whole thing out, gets to the bottom and cuts it out when it moves to the next part let’s say the eyes the end mill works it’s way with about two passes, the router stalls out, then I’m guessing from the pressure as it continues moving with the router off it snaps the endmill. Why is the router stalling out? I’ve tried running it about 16 thousand rpm’s (dial on 2 and a half) at 115 inches per minute and I’ve tried at 50 inches per minute. My plunge rate is at about 30 and my depth per pass I’ve tried .05 and .04. I’ve got the openbuilds 1515 with the router it came with. Thank you.
both those types of endmill have trouble ejecting the chips, which is probably why it is jamming up and stalling. an upcut single flute is what you want in 1/8", and make sure your vacuum is clearing the chips. I use a handheld vacuum hose and make sure I suck the chips out of the slots. you can also consider using more advanced cutting strategies...
Okay. I have one endmill left. I think it’s a straight endmill. I will try it out. What speed, feed, and doc would you recommend for cedar about 600 thousandths thick going all the way through?
I would try something like 0.040" deep, 0.005" per tooth, 18000rpm you CAM can calculate a feedrate from the rpm and per tooth values
Okay. Thank you very much. I just ordered some single flute 1/8” endmills on Amazon. Like $16 for 10 of them so they should be good to practice with. I’ll probably just wait for them to come in so I don’t break the one I have left lol.
Your .005 per tooth are you taking the calculation with the respect to mm or inches? So single flute running at 18000 would run about 900mm per minute or is my math way off?
inches. I get 4500mm/min feedrate for a 2 flute, 2200 for single flute , so 18000 rpm may be too high, or you can go for 0.0025" per tooth remember cedar has hard and soft grain and you have to set the feedrate to cater for the hard parts, the soft parts will cut just fine. also keep in mind you do not want to be making dust, you want chips, and you do not want to be recutting the chips so they must be cleared out of the slot.
I haven’t watched the videos yet and the answer may be in them but what formula do you use to determine your feed and speed?
I just use whatever web calculator comes up in google when I search for it (-: (or the tools settings in Fusion360 which will calculate when you change rpm and feed per tooth) this one is easy to use Feed Rate Calculator or Feed Rate Calculator
If you don't need the 1/8th, remember a 1/4 inch is more rigid. Use the biggest endmill for the bulk removal, cleanup with the smaller endmills if you need more details
Yeah the 1/4 will not work for this tool path. The lines are too close and they cross with the 1/4”. Thank you though
Another thing to watch out for is loose parts, need to use tabs (bridges or whatever we call them) to hold the loose parts from moving and pinching the tool. You need to vac up the chips for sure with straight or compression. Cheers Gary
