Can you turn a drill shank down with a carbide tool bit ?

[Downwindtracker2]

I 'll have to use a drill motor and a long 39/64 drill . With the arthritis in my hands they are not as smooth for grinding down.

 

[Chipper5783]

Yes. The shank is not hard (you can cut it with a file), it will machine with even just HSS. A little before the flutes it is hard - yes, you can machine it with carbide. I made up a goofy little tight spaces 3/4” drill bit, about 2” long, 3/8” shank, had to cut both ends of the drill bit off.

How far up the shank you go matters - when you are cutting the hardened material it will push back pretty hard (and the insert doesn’t last long).

 

[Downwindtracker2]

Thanks, That is good to read. I need every mm. of length.

 

[Chipper5783]

What are you trying to do? Do you just need a longer drill? You can always add on.

Drilling is usually not a very high torque application - just end drill/bore to fit the shank. Skim the new shank to ~0.6” outside diameter (for how long you need) and cut the drive end to suit the tool that will drive the drill). Assemble with Loctite (or equivalent).

I needed such for some 3/4” holes, extended a drill - results were very satisfactory.

 

[Downwindtracker2]

I've made a few long shanked drills by welding. This time I'll be reaming the holes and they have to line up. That chunk of iron is simply too heavy , so I'll have to drill and ream it where it sits. I only have a pistol grip 1/2" drill motor. I certainly had thought about the drill press though. As it is I'm expecting a challenge fitting.

 

[Chipper5783]

Welding (or silver solder, etc) an extension to a drill bit works well, especially smaller ones, or when you need a straight shank. Your drill is 39/64” (0.609” dia) - so you have a good 0.050” wall to play with. How critical is the application? What resources are available to you? If you have access to a lathe - drill a 1/2” hole in the end of some 5/8” rod, then skim it down to 0.60 to suit the depth, swap ends and turn it down to suit your drill chuck. Let the Loctite set and there is your drill.

Then keep that little tool - when you need a drill extension for a larger drill, that 39/64” will come out with a bit of heat, clean it up and pop in the new drill with some Loctite. Not exactly a quick change chuck, but very compact and simple.

Obviously your welding approach will be stronger - but mostly you don’t need it to be crazy strong.

 

[Downwindtracker2]

I'm working on a Delta Rockwell Tool maker surface grinder, a reasonable cost one when new. The table drive is rack and pinion, the pinion shaft was simply relied on the cast iron as the bearings. They are quite sloppy now as the machine is a 1968 one. A jerky drive doesn't do wonders for the finish. With a long drill, I can pick up both supports, and have a chance of getting them in line when I ream for the oilite bushings. In England, a millwright is called a fitter . This is the reason why.

I often joke I pay a dime on the dollar for the machine, but end up paying a quarter on the dollar in parts.