RPM and Feed Rate

@AllenMassey had a great spreadsheet that calculated RPM settings where can i find it ??
try to learn a better way to calculate the Feed rate plunge and all that staff :slight_smile: is not easy because most of the info is in inch.

Here it is

CNC Speed Calculator 1.xlsx (18.2 KB)

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thanks you ! let me guess your diameters are in inche too (0.125) so i need to convert it in mm :slight_smile:
and did i understand right that you use 90 for the feed rate for all of them ??

another question in V carve Pro when it say Feet rate and in some other calculators its say this
SFM = Surface Feet per Minute
RPM = Revolutions Per Minute
IPT = Inches Per Tooth
IPM = Inches Per Minute
IPR = Inches Per Revolution
is it allways the same ? or Cutting feed all those different names make me confused.

Each of those values is a slightly different measurement. SFM is the distance a cutting edge moves in relation to the surface. RPM is how many times the bit turns. IPM is the distance that the whole bit moves along the tool path. IPT (I think) is the distance that the bit moves along the tool path between one tooth starting a cut and the next one starting a cut. IPR would be the distance along the tool path per revolution of the bit.

“Feed rate” generally refers to IPM. The other numbers are all used to calculate the “ideal” feed rate for any given bit.

ok thanks Reuben but i sitll have a hart time when i get a new bit what feed rate i should use so i try to look for a formula or something i use a lot 0.8mm and 1 mm and 1.5 mm so i broke a lot of the already.

The feedrate is user adjustable in the spreadsheet, so you can change the feedrate and then see what rpm achieves an optimal chip load for the feedrate you set.

The main purpose of the spreadsheet is to show that for almost all bits and materials the Dewalt 611 should be set to an RPM speed of 1 (and that is usually still to fast)

thanks !! I will see if i may get something like that, to fix the lower speed :slight_smile: did any one use on of these ??