492-525 Center drill bit.

[WarnerConstCo.]

How big is the centering mandrel thingy?

I have 3 floors of old doors to fit into 140 year old openings.

I am drilling a ton of pilot holes and some of the jambs resemble swiss cheese by now.

Will this word for mortise strike sets all the way up to some big 4 leaf hinges?

Oh, all the doors were bought at a salvage store. 

Ughhhhh.

 

[mastercabman]

I believe it is a 5mm bit.

 

[Brice Burrell]

I believe it is a 5mm bit.

It is 5mm. I've got one, nice bit but pricey. I use mine on euro hardware and the occasional shelf pin hole.

 

[WarnerConstCo.]

I believe it is a 5mm bit.

It is 5mm. I've got one, nice bit but pricey. I use mine on euro hardware and the occasional shelf pin hole.

That is not quite 140 year old door jambs and who knows how old doors.

I wonder how long it will take me to render it useless?

Is the bit replaceable?

 

[WarnerConstCo.]

Can I put a smaller bit in it?

 

[Brice Burrell]

The bit is replaceable and I don't think you can put a smaller bit in.

 

[Corwin]

Can I put a smaller bit in it?

Brice is correct, in that you cannot install a smaller bit into the holder and have it work correctly.  The holder has a 5mm bore to accept the drill, along with a larger counterbore that accepts the spring that pushes against the centering collar.  The 5mm drill bit is held tight within the 5mm bore with a set screw.  Attempting to install a drill bit smaller than 5mm would result in the drill bit being off center -- that isn't what you would want.

 

[WarnerConstCo.]

At least the bit is replaceable.