carbide or HSS?

[iowaboy.17]

I want to turn down some BIG drill bits; they must have 3/4" shank at least. I want to get them down to 5/8" but I only have HSS 1/4"x1/4" tools for my 12" swing Atlas lathe. Before I ruin the HSS bits I have, should I run out and spend some $$$$ for carbide? 99% of my work is on mild steel or brass, so HSS works just fine. I know nothing about carbide; are there good/better/best grades? Any comments gratefully received. tom

[tp555]

You can try the hss just go slow.The drill bits aren't all that hard.Sometimes a bit too soft.Wouldn't hurt to get the carbide anyhow.

[kdiver58]

Drill bits have soft material spun welded to the shank. If you stay behind the spin weld line you will have no trouble turning the shanks. HSS will be fine.
If you have ever spun a drill in a chuck you will notice a large gouge with build-up on the shank. Hardened drill material will just spin and burnish.
The aft material is soft enough to cut with a hack saw. Do a little test cut with a file to find the hard spin weld line ..stay away from it... good luck.. k

[airsmith282]

i have used HSS for turnning shanks on drill bits and have had no problem i prefer to ue 3/8 HSS cutters my self make sure to use some sort of coolent tapping fluid or water or oil etc.. helps make for better cutting and keep the metal cool and take it slow about 200 or so not much faster..and take atlease 4 or 5 finsh passes if your not sure wahti mean its where your last pass is dont touch the the cross slde just let it pass back a few more times always seems to be that extra left over for some reason so its good to make a few finle passes on the last pass back off the tool bit when you get to the end towrd the chuck and then shut her down, if you decied to clean up with sandpaper then use 1500 gritt this way you wont ruin all that nice work you just did..

this is how i do it all the time and it seems to work fine and they all spin nice and straight..


yesterday i had to turn the shank down on my fly cutter for my mill same process slaped it in the milll and tryed it out worked really nice for me better now then it was new