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Are carbide rasps acceptable for use in a VMC?

TAIWA NUMBA WAAN

Aluminum
Joined
Mar 9, 2021
I was in a machine shop store this morning buying parting tools and I saw a rack of carbide rasps that look like reduced shank lolipop cutters, tapered barrel cutters, and bullnose cutters. Some of them are ground and visibly look to have the same edge quality as an uncoated carbide endmill for aluminum. They're like 10 dollars each, I'm wondering if anyone uses these for CNC machining? I've never used rasps before but the bullnose reduced shank cutters in particular would be very useful to me. Or maybe this comes across as a "just go sideways with a jobber drill in a drill press" question....But maybe it's worth a try?

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You can use them if you work within their limitations - they're usually not as stiff, concentric, or diametrically accurate as proper endmills.

Also need to keep speed up, feed and width of cut down, and coolant flushing high. Pretty good on stuff like some plastics or composites, not really suited for steels IMO.
 
I have used Burrs for all kinds of things in Aluminium and used to engrave in steel.
Just know it has bigger limitations than a cutter and you should be just fine.
 
Hi TAIWA NUMBA WAAN:
Carbide burrs have a different cutting edge geometry from endmills because they're intended to be used differently.
They are designed to be controllable when used in a hand held rotary tool as you know.
So they are made to be less grabby:
1) Lots of small flutes so no individual flute can take a big bite
2) Less or no positive rake so they can't dig in so easily.
3) Less primary relief and often no secondary relief so the cutting edges are not as sharp and not as fragile.
All the ones I have are form relieved and have gashes in them to break up the chips (like a corncob rougher)

As others have remarked you can press them into service in a pinch for certain tasks but they are not good substitutes for endmills.
To get an idea about how they are different from endmills when being used, try putting a 1/4" 4 flute endmill into a die grinder and swiping it over a piece of steel.
Hold on tight when you do.
Next put in a 1/4" carbide burr and do the same thing.
The difference will be obvious.
It kinda works the same way in reverse.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
To get an idea about how they are different from endmills when being used, try putting a 1/4" 4 flute endmill into a die grinder and

Worked in a shop with no mill.
Needed some grease grooves and slots in a face (soft durabar)
Die grinder in manual tool post 0.25” endmill. , put the chuck in a low gear. X axis and hand rotate the chuck. Done! (No accuracy required)

Do what u gotta do!

Service manager was jaw dropped. They had farmed it out for 20 years. (Infrequent job, one man lathe bay supporting a repair shop)
 








 
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