[rcazwillis]

I purchased a 3/4" screw length drill bit. I did not expect the shank to be 3/4" also. I have a 5/8" chuck. How do I turn down the shank to 5/8"? I have a 7x lathe. Do I have to grind the shank or will standard tools cut it?

[Traceycnc300]

I have cut the shank down on several drill bits with carbide inserts with little trouble but the lathe I was using was heavy duty.Dont think youll have much of a problem if you take small cuts.Make sure its running as true as possible.Use collet if you can.

[mxtras]

Carbide will cut it - no problem. Drill shanks are typically a bit softer than the flutes.

Good point about ensuring it is running true!

Scott

[ViperTX]

yes, I turned down some bits for a friend....carbide cut through the shank without any problem on my 8x14 lathe.

[rcazwillis]

Thank you. I will try it this week some time.

[WhiteTiger]

I've had good luck using just m42 cobalt bits. Especially on larger drills (3/4 to 1 3/4 is the range I've cut) the cutting is easier than with carbide (imo) and the resulting finish is very nice.


Tiger

[RotarySMP]

Drill shanks are normally quite soft, as they are not tool steel. A plain steel shank is welded onto the HSS fluted portion. Think of how easily they burr when they spin in the chuck. You can turn them easily with HSS in my experience.

[JPMach]

If you have a collet chuck it will usually run pretty true too. As Rotery said the shanks are not tool steel but just soft steel like a 1045 or so, turns very easily with regular tooling.

JP

[Sixgun]

Someone recently brought me 4 reamers, 2 of which I machined the shanks from 3/4" to 1/2" so that they could perform a simple task with a 1/2" hand drill. The other two of the four reamers I could not machine because the entire tool shank and all was hardened. So my question would be should I anneal the shank so I can machine or will this cause problems in trueness of the tool?! Ahh, the delimma!!!

SIXGUN

[neilw20]

Sixgun. Just use tungsten carbide insert. You will turn it readily.

[Sixgun]

Thanks Neilw20, that is just what I was hoping to hear!!!! I kept thinking I had heard that before but was thinking maybe I was just wishful thinking!! Haha!!

[neilw20]

I've even turned grooves and shoulders on the outer rings on ball races.
Do it a lot slower than normal and usually no coolant. Compressed air is OK.
Unless you have 100% flood coolant you can get microchipping of the insert, and as the chips come of blue (normal) the coolant can increase the HP considerably.
With the chips coming off dark it is a good sign that most of the energy is going into the chip.
Push the feed more than you think. At least 0.002" thick -- make it work. Yes, it will probably squeal. That's why earplugs are good.

[juergenwt]

Drill shanks are normally quite soft, as they are not tool steel. A plain steel shank is welded onto the HSS fluted portion. Think of how easily they burr when they spin in the chuck. You can turn them easily with HSS in my experience.

Roatary you are correct. Juergenwt.