Corner Rounding Endmills

[lynnl]

How are the dimensions of corner rounding endmills expressed? Is it describing the radius of the rounded corner? (my guess) ...or the diameter of the cutter itself?

For occasional use, could a carbide router bit be used for that purpose? (on aluminum)

[This message has been edited by lynnl (edited 06-02-2003).]

[SGW]

Radius of the resulting corner, as you surmise.

I expect a carbide router bit would work okay on aluminum.

[DR]

Yes, carbide router bits work well on aluminum. In fact, they work much better than a "conventional" corner rounding end mill. The corner rounder's are ground with zero rake for easy resharpening. Zero rake is very bad in aluminum.

Don't buy the rock-bottom budget bits. Stick with a decent brand and you'll have good luck. We use them all the time in aluminum and plastics. If you don't have flood coolant on your machine a little spray of WD40 or equivalent helps.

[spope14]

Us real cheap shop rats have used router bits for steel as well. Bought a 90 degree bit and used it on a 200 piece job just last month as a .030 edge chamfering (duburr) tool on 1018 steel, still have it, and it is in good shape. Programmed it on the CNC to do so. Lost my good 90 micrograin tool on a student "touch off" setting the offest, this was all I could think of during lunch to finish this job (we run jobs to supportthe program now and then).

Corner rounded some 1018 with a 1/4 rad router bit two years back in a pinch, would prefer to do it right next time though - not really recommended, even for alum.....though it would work with .010 depth of cut.

Speed, feed, and consideration of rigidity and the idea that the shank is real small and touchy, and probably of poor shank material. That is the key.

Best buy the right tool, but us el-cheapo teachers and real crafty (read too chep to buy the tool, or too impatient to wait for delivery) metal butchers learn to use what should not be used and to use it well.