flatten tapers drills

[oldtools]

Found 2 brace type drills with unusual drive heads, flatten tapers.. doesn't look like it would fit into a regular brace (square taper)..  what type of tool is used to drive these drills?   anyone  know or seen these type of drills?

[PFSchaffner]

I don't know but I have some too.

[oldtools]

Closer look...  looks like they were hand ground, not factory machined..  why?

[PFSchaffner]

I finally dug one out. It certainly *appears* to have been machine-made (i.e. not modified), but one never knows. For one thing, the broad surface has a stamped marking on one side (the other side has an off-center detent-style hole). The marking is difficult to make out, but says something like:

  PREUHER
    THIEL

"THIEL" is quite clear. The first word much less so. Indicating degrees of uncertainty with layers of parens, I'd transcribe as

PR(E)((U))(((H)))ER

This means nothing to me.

[PFSchaffner]

and here's the 'detent' hole and the narrow edge:

[john k]

I wonder if these were made not for a brace drill, but for a wooden  Tee handle drill?  Especially with the European sounding name, brace drills were not as common over there.

[Billman49]

I was just thinking the same thing, but you posted while I was watching TV...

[oldtools]

Thanks guys, makes sense..  hopefully someone knows for sure what they are...

[Chillylulu]

Some braces didn't have adjustable collets, but they did have a wing nut or set screw.

My swag is a fixed collet that fit these ends.

Chilly.