hello all,Ive read just about every article I can get my hands on, including the half dozen one here, and none answer my question.
I am making a cut with a 3/4" bit and need to calculate feed and plunge rate. But every formula that I have found, does not offer up a 3/4" bit option. I KNOW that this affects the calculation because I know that the blade on a bit at 3/4" is traveling faster that that on a bit of 1/2". But how do I calculate this (call me"Mr. Failed at math in HS")?
Is there a feed rate (chip load) calculator out there that you recommend that I can put odd sized bits and get the ideal plunge and feed rates?
The project on which I am working is a āmust get it right the first timeā as I do not have any scrap material to test it on. Iāve made test cuts on other scrap wood and am satisfied with what the final cuts will look like, but I need to calculate the right feed rate for a harder wood.
as always, and assistance will be greatly appreceated
This is what I would do. YMMV. First off, Iāve never consulted a chart in 18 years of doing this.cnc thing and 50 years of using a router. I go by sight and sound.
I guess you could find the specs for a 1/2 inch bit and then enter numbers that are slower and shallower than that. Then test it out on scrap wood and see what it looks like .This guy uses math and itās just multiplying 3 numbers together on a calculator.
Bit speed and feed formula
Bit speed and feed formula
I have a formula for feed and speed that works well.
Spindle hp X 80 x bit diameter = ipm
For 7.5hp spindle. Bit diameter x 600. If you have a .250 bit times that by 600 and you get 150 ipm
Lets say you have a 5hp spindle you would use hp times 80 = 400 so you take bit diameter x 400. thatās .250 x 400 and you get 100 ipm.
I have used this for years and works well. Itās a good start point for most materials.
Try it on scrap first.
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Thanks Martin. The more that I read this, the more confused I become. I say this because it does not discuss RMP. Iād have to look up the specifics of my x-carve pro (shouldnāt be hard) and enter them into the aforementioned formula, but how does that apply to how fast that blade is moving through the wood?
Iām only now concerning myself with chip load and feed rate because this is a āmust get it right the first timeā type of project. I donāt have time to build a butcher block to use as āscrapā to test this. And what I donāt understand is; how can I calculate chip rate without speed of the blade? How to I calculate speed of the blade without a formula for calculating the spindleās RPM by the bid diameter?
It seems like it should be basic stuff, but my searches and hours of reading articles have led me nowhere.
Maybe join one of the X-carve facebook groups?
(1) X-Carve Users | Facebook
that of course would require me joining facebook. the answer must be out there somewhere
thinking that I just say" F-IT!!" and set my plunge depth to 1mm, and my plunge rate really slow, and cut the feed rate by1/10th, let it take forever to carve, and just deal with the burning and sand it thoroughly when it is finished. Better burnt than chipped out.
Using a router, I seldom concern myself with chip load, the 65 mm routers we use just do not have the power at lower rpmās so if you have done soft wood carves to test, just slow the feed, reduce the step over and doc per pass. Err on the side of slower and you will do fine.