So you get 3 bits in a pack and they reach a little longer than my more expensive bits which i needed to get the 1.5 inch pocket for these boxes im doing, material is Oak.
First try, I did at .2 max depth , with a 80 ipm feed rate but had the router turned up to high i believe, about 3.5 to 4 on the dial. This snapped the bit about half way into the first box.
So round two I changed my settings to shallower cuts, but the once the bit started taking full cuts, with the 40 percent step over it started getting arratic and I shut it down, the bit was blue from getting to hot.
So after a little reading on feed and speed, I tried to get as close to the chip load recommendation as possible and turned down my router speed to 2 on the dial, which is supposed to be about 12,000 rpms , with a 2 futes on the bit, and ran up my ipm to 180 and brought back up my depth of cut to .2, again seemed to be going fine cleaning up what the last bit left behind but when it started take full cuts it bogged down the router motor and snapped the bit soon afterward.
So now I am a little hesitant to put in my new $40 carbide bit and try the same settings on my last attempt, would appreciate everyones thoughts on this, ty.
Yeah, they are all 2 flute bits, these are going to be round boxes that have a 1.5 deep recess in them and a lid. According to most charts Iv’e read , .009 to .011 chip load for hardwood is a good place to start, so at 12,000 rpm and 2 flutes at 180 ipm get me close at .008 chipload. I think one of the limiting factors is the router not having the torque needed to achieve lower rpm rates, and may be that these bits are two cheap to hold and edge long enough, when a i plug the values you gave me into the formula that gives me a .004 chipload which i not sure but think it might be running the bits a little hot because they are not removing enough wood to release the heat of friction , in other words they are sitting in one place to long and begin rubbing the wood rather than cutting if this makes sense. Maybe this will work but may be less than ideal because fo the limiting factor of having a router and not a spindle. I think i will try one of my shorter carbide bits and see how that goes at my last setting and if this does not go well i will try your recommendations, thank you for the reply and I will let you know how it goes.
So, i decided to run at 150 ipm, at 12000 rpm, and even with the better bit this did not sound good and started chattering, so i dropped it down to 100 ipm like you said and it sounded much better but still a little chatter so i turned the rpm’s up to about 2.75 on the dial and it seemed to run pretty well then, I was still getting nice chips and not dust. So when i get my deeper bit in the mail I guess this is what I’ll start at, ty.
Funny, but I have the opposite philosophy. I figure that if I buy good carbide bits then I can cross one thing off my potential issues list if I run into problems. Buying cheap bits for one-off throwaway use might be okay but I don’t do a lot of that kind of stuff. HSS just doesn’t seem to play well with the very high speed of our routers. Once you’ve gotten over the new-user breakies, I think it pays to buy quality.
I have the same end mill. Spetools are real carbide & not in the category of “cheap” like HSS ones. They are cheaper than Amana or upper tier tools though. I like them because I can get them quickly and wouldn’t be too upset if one broke. Good solid bits. I just don’t think there’s any reason not to go with carbide bits and cheating out on HSS instead.