Mill bit for cutting HSS

[John AitkenParticipant @johnaitken84086]

I was wanting to cut some 6mm HSS Lathe tools down a bit. I tried once with an 8mm end mill which failed probably because the tool was only for 45HRC.

I was wondering if the mill bit would work as it goes to 65HRC-

https://www.shop-apt.co.uk/high-hardness-high-speed-carbide-end-mills-4-flute-65hrc/high-hardness-high-speed-carbide-end-mill-8mm-diameter-4-flute-altins-coated-65hrc.html

[John AitkenParticipant @johnaitken84086]

[old martParticipant @oldmart]

It should work, although I have only cut case hardened, not HSS. Use the highest speed you can, and cut dry. I did use a carbide drill to remove a broken tap with good results. Do not touch down on the work with the cutter stationary, you will chip the flutes.

[VicParticipant @vic]

I’ve found HSS cuts quite well on a Lathe with carbide tools. Not yet tried it on the mill though.

[Anonymous]

Any carbide milling cutter will work fine in HSS. Here's an involute shape milled on the end of a 1/4" HSS toolbit prior to using it to cut an internal gear:

The cutter is a 3 flute uncoated carbide slotdrill. Similar to turning hardened steel use reasonably high surface speeds, shallow DOC and high feedrate. Ideally the shear zone should be red hot as that will soften the steel where it is being cut, but leave the bulk of the material hard.

Andrew

[Author]

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