Cutting speeds for Hole Saws

I would like to find a rpm chart for cutting steel with a hole saw. Anyone know of such a creature? For example I have one two inch hole to make in some plate steel. A slow rpm but how slow? Thanks! Scott

Reply to
ShakasCaregiver
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Use a regular drill chart, I would stick down on the low side, maybe

50-60 fpm or 100-120 rpm plus lots of oil or cutt> I would like to find a rpm chart for cutting steel with a hole saw. Anyone
Reply to
Machineman

Your hole saw has what kind of teeth? If they're tool steel, then use 70 SFM. A 2" hole has circumference PI*2 or about 6 (roughly). In feet that's about

1/2. So if you run it at 140 rpm you're do> I would like to find a rpm chart for cutting steel with a hole saw. Anyone
Reply to
Grant Erwin

Tool steel?

Regards,

Robin

Reply to
Robin S.

Tool Steel - generic term for hardened steel used in metalworking. The most common tool steel, by far, is "High Speed Steel" (HSS). HSS as opposed to ordinary *carbon tool steel* requires more complicated heat treatment. Ordinary tool steel such as drill rod can be heat treated in the home shop. HSS cannot - or can't be easily heat treated without the controlled environment of a high-temp oven. High Speed Steel was "all the rage" in the metalworking world of 100 years ago.

Bob Swinney

Reply to
Robert Swinney

Yeah yeah yeah, but go and ask a punch/die supplier for a "tool steel" punch and see if he offers one in HSS. More likely the next question will be "O1 or A2?")

Bimetal hole saws (standard high-quality hole saws like Starrett, Milwaukee, Lenox, etc.) use HSS teeth and alloy steel bodies.

The bottom line is that while HSS is a "tooling steel" it's not exactly interchangeable with "tool steel" as far as industry is concerned.

Regards,

Robin

Reply to
Robin S.

Drill a few holes on the waste side of what you are holing for a place for the chips to go, sawing the chips over and over doesn't contribute anything.

Reply to
Beecrofter

I have just such a chart from a Blu-Mol "The Aggressor" Bi-Metal 3.5" hole saw. I put it aside when I opened it last week, thinking it might be useful someday--looks like someday has arrived rather soon. Here are the recommended RPM settings:

Mild Steel: 95 Tool & Stainless Steel: 45 Cast Iron: 65 Brass: 130 Aluminum: 145 Max RPM: 750

Reply to
Jedd Haas

Within 8%, the below speeds can be used as suggested SFM for bimetal hole saws for various materials. In other words, if 95 is the optimal cutting speed for a 3.5" bimetal hole saw in mild steel, then we think:

SFM = RPM * PI*D/12

And we notice that PI* 3.5/12 = 0.92 which roughly equals 1 (within 8% like I said). So for 3.5" hole saws only, neglecting the 8% error, the equation becomes

SFM = RPM

and thus the recommended surface feet per minute for bimetal hole saws can be inferred directly from the table below. To figure the correct RPM for a bimetal hole saw of a different diameter in any other material use the above formula.

Note this is only good for bimetal hole saws. Also, note it won't hurt much to run a little slower. And yes, lay out your circle and drill a hole tangent to your circle to allow chips to fall out. A real smart machinist will drill this hole in the waste material :-)

Grant

Jedd Haas wrote:

Reply to
Grant Erwin

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