Tormach Feeds & Speeds Basics

Maker Talk Dumb Questions Invited
1

I got a 1/8" carbide end mill from Lakeshore Carbide that I’m interested in using on 1018 mild steel. ProvenCut doesn’t seem to have anything close, but Lakeshore has a General Purpose Endmill Speads [sic] & Feeds chart. It says that the SFM for low carbon steel is 250-500, and gives the formula RPM = (SFM / DIA) x 3.8.

Does that mean that the low end of the speed range for this mill should be (250 / .125) * 3.8 = 7600 RPM? Really?

ProvenCut’s data for a 3/8" end mill suggests 1500 RPM, but this formula gives 2533, so I’m hesitant.

2

PS. I actually got three of the 1/8", and two of the 3/8" so when I inevitably break some, it’s not the end of my day.

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3

I always take extra endmills with me in case of this.

I feel like I would take demonstrated data over theoretical data from a trusted source like ProvenCut. Theory’s helpful as a guideline but not always the optimal solution in the end.

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4

when using proven cut you can select 4140 as a alternative if there isn’t 1018 steel toolpath avaliable

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5

How important is it that the recipe is for a Tormach 1100?

6

Not that important use any of the Tormachs

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