In determining the feed rate, formulas ask for RPM and chip load. The RPMs is pretty easy to figure out, but what about chip load? When you’re cutting through MDF, you can’t exactly measure the size of your chips, can you?
I don’t want to post any equations if I am wrong without first clarifying that I am only making a guess here. So please, do not just run with these numbers if you happen to come across this post.
In my example, I am attempting to clean up and level out my spoil board/work surface. I do not need to take off much and looking to remove 1mm. I have a fairly large work area of 24x35 inches and this can take some time, so I would prefer to do this quickly yet preserve the life of my bits.
For a bit, I have a 2 flute half inch flat cutting bit (12.7).
I took this info from http://www.pdsspindles.com/engineering-speeds to get a benchmark of chip loads for different materials and bit sizes. Though I am unclear if depth makes a difference.
Going off of the lower value for MDF and a half inch bit, I’d get .025.
But if I look at http://www.shopbottools.com/mTechShop/files/ChipLoad_inch.pdf I would get a large range of .005mm-.030mm.
.025 would seem reasonable for such a low depth, but calculators would then give me a feedrate of 1400. This is quite a bit of a jump from the 500 that seems to be a baseline. Now, I would love to increase the speed this much, but is it safe?
Feel free to jump in and add your two cents.