How important is controlling RPMs for carbide burrs?

[Granite80]

I recently acquired a nice, used set (8 pieces) of ¼" shank Snap on Carbide burrs for a good price off of flea bay.

The label specifies optimal speeds for each bit on two different types of metal (iron/soft steel and stainless steel). The optimal speeds range from 16,000 to 33,000 RPMs and it says tool damage may occur if not running at these speeds.

I don't use these professionally - I am a hobbiest working on vehicle modifications and other do it yourself creations/inventions. I frequently find myself needing to enlarge a hole, trim metal brackets, etc, which is how I use the bits. I use them practically every week, but not heavily.

Right now I have a cheap HF die grinder so am not even sure what RPMs it actually puts out. And, searching around, I can't find ¼" air die grinders that spin at 33,000 RPMs...

Two questions for the experts/pros here:
1) How important is it to run these bits at the recommended RPMs
2) IF important, can you recommend a reasonably priced air die grinder that can control the speeds over this range (16,000 - 33,000 RPMs)

Thanks in advance from a novice trying to learn!

 

[plinker]

An air regulator would be your speed control, more or less. The average die grinder is 25K rpm, 20K for a right angle type. I would try running at 60 psi and go from there.

One piece of advice is let the cutter do the work, meaning dont force it. That takes out bearings.

 

[Granite80]

Thanks

 

[Monte]

If you reduce the air flow you´ll also reduce the torque.....
I personally would get an electric die grinder with speed dial so you can exactly adjust the speed. If you use carbide burrs with too high speed the teeth can wear, if you use them with too slow speed the teeth might shatter. Pay attention if you enlarge small holes ! Hold your grinder firm in your hands and make sure that you don´t cut too deep in one direction ! The burr might recoil and shatter ! Carbide is very brittle.

 

[Granite80]

Thanks for the tips. Very helpful. I have seen chips on burrs from running at too slow a speed

 

[shamrock12]

I always run them on my die grinders at wide open throttle. They usually spin at around 25,000rpm which falls within the range of most 1/4" carbide bits out there. I have observed that it is much more important to keep the cutting tool steady on the workpiece and not allow it to chatter around excessively. That is probably the biggest killer for the carbide bits.

 

[uart]

How important is it to run these bits at the recommended RPMs

Hi Granite. I think that the main problem with running at too lower speed is that it's tempting to push it harder to compensate. So if you do find yourself cutting a lower than recommended speed, just remember to keep a light pressure and take it easy.

 

[Tim37]

Run it wide open you will do more damage by going slow than too fast.