Drilling/threading HRC60

tcncj · Feb 14, 2018

Hello members of PM

I need to make some M8 size threads in HRC60 steel (vise). I've never machinined steel with this hardness before.
My idea was to use a simple 6.8mm carbide drill and use a thread mill to cut the threads.
If I'm correct I should use no coolant (maybe some air).
Should I pre drill it with a smaller drill? any advice is welcome

Larry Dickman · Feb 14, 2018

use coolant, lots of it. A coolant thru drill would be even better. DO NOT pre drill it. Don't peck it, either.

Quantity? Thread milling will work well. If you want to tap it, I used to use OSG VC-10 taps with moly-dee with good results. However, it that past few years Emugee and others have come out with some new taps for hardened steel that are supposed to work great. (Not tried myself, yet)

tcncj · Feb 14, 2018

Quantity? Only 8
Recommendations for speed/feed starting point?
I don't want to use a tap. They probably ain't cheap, and I'm too scared to tap in HRC60 haha.

metlmunchr · Feb 14, 2018

MA Ford Hi Roc straight flute die drill will drill the most beautiful holes you've ever seen. 17/64 is dead on 6.75 mm. About $58 from MSC. Likely cheaper from other sources.

60sfm and .001 ipr feed

No recommendation on tap or thread mill as I've never threaded anything that hard.

White Lightning · Feb 14, 2018

I haven't tried this but thought it was interesting. I hope the link works. It's the first time I have tried linking a video.

EDT \\ EPOCH DIRECT THREAD MILL - YouTube

Sent from my XT1585 using Tapatalk

Matt J · Feb 15, 2018

White Lightning said:
I haven't tried this but thought it was interesting. I hope the link works. It's the first time I have tried linking a video.

EDT \\ EPOCH DIRECT THREAD MILL - YouTube

Sent from my XT1585 using Tapatalk

Used them in 55Hrc not 60 but worked really well. Initially drilled them and then used the treadmill but after struggling with the drilling, sacked that off and went in to solid. Worked spot on. Just wouldn't fancy using the M2 version :willy_nilly:

Have nothing but good to say about MMC Hitachi tooling for hard materials

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