Reducing Drill bit shanks

[rickard]

Right now I'm working on a Home Brewed Lathe/Mill because my Taig and Unimat are to heavy to carry around. My design Considerations are I really don't need anything bigger than a 1" Swing and a 6" Bed. So I've settled on the idea of using a spindle a buddy of mine made for me a while back that is the same thread and inner tapper as a Dremel, so I can use Dremel chucks and collets. I also intend to reclaim the spindle from one of my junk Dremels for the tail stock. Now I reccon I won't use any bigger than a .500 drill bit but the Largest Collet is .125

So my Question is what about the thought of Fabing up a tool post grinder and chucking up drill bits from .126 - .500 and grinding the shanks to .125. is it reasonable to think I could chuck them up in 3 jaw chuck on my Unimat, and maintain concentic while grinding down the shanks ? Any thoughts on this???

 

[Tony Wells]

Most drills aren't hard on the shank end. They would be difficult to grab in a chuck if they were as hard as an end mill, for example. You can turn them conventionally. No need to grind them. Chucking the flute end is another problem though. You might be able to, but I haven't had much success with it in general. Collets work best for that, or made sleeves that are split to allow chucking will work.

 

[12bolts]

If you put an 1/8" shank on a 1/2" bit, you'll tear it off trying to use it.

Plus 1 for that, although I wonder if your power source would have the guts to run a 1/2" bit into anything hard.

Cheers Phil

 

[rickard]

Plus 1 for that, although I wonder if your power source would have the guts to run a 1/2" bit into anything hard.

Cheers Phil

Phil I'm banking I'll have all the power needed, I'm using a Cobalt Open R/C Motor and gearing it down for monster torque. Which is purely academic Since for my requirements are >= .062 Brass , Aluminium, and Plastics.

 

[Hawkeye]

Since your materials are all that thin, pick up a step bit with fairly fine steps. It will work up to 1/2" in small bites.

They are available with 1/4" hex shanks. Redesign your spindle for that format. You'll like it a lot better than a Dremel chuck.

 

[george wilson]

See the acrylic thread here for my GOOD advice on preparing drills for drilling acrylic or sheet metal and brass. You will save yourself a lot of grief,and possible injury if your drills DO NOT grab.

I've had a nasty cut from THICK brass grabbing,sucking it right up out of a TIGHT drill press chuck,when the bit grabbed while emerging from the other side. Took 10 years or more to get the feeling back in the tip of my finger from a severe laceration caused by the CORNER of the thick block of brass. Laid me wide open,severing the nerve.