Understanding Manual Cutting Speeds/ FeedRates


I’ve been trying to learning how to use the CNC router at the local makers-space but I am having lot’s of difficulty. I am finding that, if I use the automatic settings after I type in the information about the router bits, the speed/feed/plunge-rate take hours to cut. It took 3hrs to make six 1/8 circle engravings on 1/4 Russian birch. It’s absurd, beyond conservative.

I really need to be autonomous and need to learn how to adjust speed/ feed-rate/plunge-rate. Pretty much need to know everything to be able to bypass Carbide Create’s automatic settings for when it is slow.
Could someone guide me to the right information and please explain like I am 5.

The bits I have been using:

V-crave/ Engraving Automatic Settings were:
Bit Diameter: 0.562 Depth per pass is .113
Flute Length: 0.437 Step over 0.253
Angle per side: 30 Feed rate: 27.2
Number of Flutes: 3 Plunge: 4.53

Speed on Router :4

I also have this bit that I want to cut the wood after the engraving.

Flat WindMill
Bit Diameter: .250
number of bits 2

Thanks for your help.

Sympathise. I’ve been trying to wrap my mind around this sort of thing for a while now.

Suggest starting with the official recommendations: http://docs.carbide3d.com/support/#tooling-support and http://docs.carbide3d.com/support/supportfiles/S3_feeds_250.jpg

Then look into using the testing technique here: http://www.precisebits.com/tutorials/calibrating_feeds_n_speeds.htm

Been trying to work up a tutorial here: Tutorial on feeds and speeds but it’s nowhere near complete. There are a bunch of additional notes at: https://www.shapeoko.com/wiki/index.php/Materials which may be of help, or may just be confusing noise.

Thanks @WillAdams. I will definitely follow up on those links. Please keep up the tutorials, it’s needed!!

Perhaps talk to the makerspace about getting a licence for GWizard’s calculator? If they subscribe for 2 years they’ll have a perpetual license that covers the S3, and if they get other milling machines it should work for those too.


Are these numbers in inches?

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Yes, they are in inches.

I run my v cutters at a feedrate between 80-110ipm. With a plunge between 20-40ipm. And the doc is at .07-.100. These depend on the wood I’m cutting the harder the wood the slower I go.

Thanks! Just looked this over, very cool! I’ll ask!

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