Feeds and Speeds ... can't wrap my head on it

So I’ve been reading up and watching all things feeds and Speeds and can’t seem to wrap my head in understanding what to do. There are times I hear my makita router make high shiver pitch sounds that is just as annoying and nerve wracking. Not sure if its caused by the bit going against the grain or not.

I typically just set the rpm from what CC or Vcarve pro says and let the software do the rest.

What am I missing?

With CC the rpm is at approximately 10k rpm.

With Vcarve pro the rpm is at 16k or 18k rpm.

What I understand is it’s about the chip load and to derive at the correct chip load depends in the rpm and feed rate (ipm). Then there is depth of cut (doc) which should not exceed no more than 50% of the bit diameter.

Hi @GIban671,

It’s quite a normal phase to go through, we’ve all been there and to be honest it seems to me that most of us never really master the feeds and speeds completely, there is no universal answer, we just branch off to our preferred approach for it, be it experimental, theoretical, or a mix of both.

I have tried to document my view on the F&S topic here, in case you want to give that a read:
https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z/feeds-and-speeds-basics

This is by no means a definitive answer, but it may help you get a grasp of the various parameters that are involved in getting a “good” cut, how they interact, and how to determine suitable values.

It this is too much theory for you, feeds and speeds values from @wmoy’s MaterialMonday videos are your best bet, until they get integrated in CC by default.

2 Likes

Julien’s book is excellent and highly recommend it.

I use Julien’s basic F&S calculator, it shows a range of chipload for different material/bit size and taking into consideration if you are doing a contour vs a pocket toolpath since the whole bit is engaged in a contour. You can do these calculations in VCarve 10. Here are his recommended chipload targets recommended:

image Chipload guideline

4 Likes