What purpose of screw in Forstner Drill Bit shank

[Dominik Pierog]

Hello.
I cleaning my old forstner drills and one have this little screw in shank.
I unscrew it and there was only piece of grease inside. This is a blind threaded hole.

 

[Inspector]

Could have been for an extension to drill deeper holes.

Pete

 

[Rorschach]

Might be for adding an extension shank but I suspect it is a remnant of the manufacturing process.

 

[Inspector]

Great minds think alike and at the same times it seems.

Pete

 

[Dominik Pierog]

This screw have diameter like 2-3mm and proper extension looks that

Might be for adding an extension shank but I suspect it is a remnant of the manufacturing process.

If its remnant of the manufacturing process why they bother to put screw inside?

Maybe drawbar?

 

[Rorschach]

No idea why there would be a screw in there.

 

[Inspector]

If it was originally made with a Morse Taper then a drawbar makes sense. If it was always a parallel shank then I don't see a purpose in a draw bar. Does it look like it might have been modified? The screw in it might just be to keep the threads clean until needed.

Pete

 

[Dominik Pierog]

No its was brand new buy in local store years ago. It have standard 10mm shank.

 

[Chrispy]

It's for setting the length in a drilling machine, you adjust the set screw which then bottoms out on the chuck/collet , then you can remove and replace in machine without resetting depth stops etc. Hinge boring machine.

 

[Phil Pascoe]

I didn't know, but I was about to suggest that.