Cut a keyway in a piece of hardened steel.

[NeoTech]

So ive got this ER32 tool holder.. its a straight shank 20mm with a 10mm drawbar rod.

I wanna cut a 4mm wide keyway in it. about 0.5mm deep. Just so that it will pass into the W20 spindle i have on my Aciera machine.


Before i go and bang up a good tool.. I ask (sometimes) dumb questions.. like.. What kinda endmill should i use?! I have alots of HSS kinds
but im guessint. those will not work.. at all.

[hopefuldave]

Hi, I'm not familiar with the W20 collets of which you speak, and I'm not sure whether the keyway's going to be just for clearance or drives the shank, but...

A carbide endmill would probably cope, and would let you bring the keyway close to the back of the ER chuck - high spindle speed, light cuts, plenty of coolant? I think you're right, HSS would struggle!

If not, have you considered grinding rather than milling the slot? If the 20mm shank can be released from the chuck this might be the best way to go, the keyway can be cut right to the end of the shank if necessary (more likely you'd just need to come as far as the rear of the chuck body). A Dremelloid with a 4mm thick mounted Alumina wheel would probably do it if you can arrange holding it

Dave H. (the other one)

[Darren]

I've cut these with a carbide endmill in the past, no drama as carbide will cut it like butter 

[raynerd]

Are you cutting the keyway in the straight shank at the end? I only ask because if it is anything like my straight shank 12mm, ER16 chuck I purchased off ebay from china, it wasn`t fully hard at all anyway!!

[andyf]

Chris is right - it may not be very hard. Try scratching it (longitudinally, where the keyway will be) with an HSS tool. Usually, if HSS will scratch it, it'll cut it

Andy

[NeoTech]

Oki, not sure if its chinese actually. i bought one of these:
http://www.totoolsupplies.co.uk/uk2ecommerce/product/straight_shank_er32_x_50_x_20mm_collet_chuck_std_nut/

But i will try that, scratching it with a HSS tool.. and if its scratches i guess i try to skim cut it all so gently.. =)

[John Stevenson]

Modified quite a few in different ways and not found one that a carbide tool won't handle.
Many are just tough as opposed to being outright hard.

[NeoTech]

So i found an old HSS Co5 4mm. 2 flute bit.. it actually cut this.. but 0.02mm at a time.. and i had to keep air pressure on it at all times.