I have a few unhardened HRS studs with 1/4-20 LH threads on the end, which I didn't turn down enough- they're big enough that they won't fit in the holes I just threaded with a proper tap- the OD is not unreasonable, but the threads aren't deep enough. Otherwise the studs are fine, so I'd like to deepen the thread by maybe 3 to 5 thousanths or so. I've tried re-chucking and threading a little more, but its really hard to get everything set right and the consequences are a wrecked thread.
Since its just a couple studs that need help, I was thinking I might be able to build a cheapie die (avoiding paying McMaster's highway robbery for such things) by drilling & tapping a short length of 1" diameter stock, then slitting it to provide relief for the swarf/chip/turnings (I still don't know the difference..)- and hardening so the sharp edge of the slit will last long enough. Maybe I could run the slit in at something less than perpindicular to the tangent of the stock to give the edge a bit of rake. Maybe I could also be clever and slightly ream the end of the hole to introduce the edge more gradually.
Would this work, or is there a better approach?
Thanks,
Gregm