What is this thing called?

[Stuart Davenport Knives]

Hey guys, what is the technical term for this bit? It is used with corby bolts to make sure the corby head is drilled center to the shaft. I need one that is a 3/16" shaft / 1/4" head size, but for the life of me I can't think of what it's called. I have used a 1/4" drill bit before to get the job done, but would prefer to get the right tool. Thanks in advance.

 

[SpotOne]

Step drill bit?

 

[Daniel Fairly Knives]

I can't tell what I'm looking at but Aircraft Counterbore?

 

[Retired Spook]

CNC scribe / engraving tool?

 

[DanF]

Make sure you get one where you buy your corby’s, all are not created equal for some strange reason. I heard them called Corby step bits.

 

[Hengelo_77]

Step drill or counter bore.

 

[Stacy E. Apelt - Bladesmith]

Step drill or counterbore. Yours ( poor photo) seems to be piloted.

I would like to re-emphasize what Dan said - get a good counterbore that matches the Corbys you buy. It is well worth the cost to get a carbide counterbore.

 

[Robert Erickson]

I'm pretty sure it's a rivet drill bit from the picture. Looks like Jantz has them.

Rivet Drills

Knifemaking hobbyists will appreciate the high quality rivet drills on offer at Jantz Supply. Rivet drills are designed to drill and countersink rivet holes in one step.

knifemaking.com

 

[Stuart Davenport Knives]

That's it Robert. That is exactly correct. Rivet Drill. Thank you very much. I knew it had a specific name but I couldn't remember it, so searching for one was a problem. I'll head to Jantz right now.

You da man! I have one for smaller corbys (above photo), but I ordered larger corbys this time and need the right "rivet drill" for a 1/4" corby head.