Vintage Madison spade drills, revive or repurpose?

[Cannonmn]

Have several old Madison or Madison-type spade drill shanks shown, no blades/inserts. Someone apparently adapted two to shorter inserts with a key stock spacer. For larger holes we have twist drills but I’m going to invest in a set of annular drills to use in the Bridgeports. We’ve never used spade drills for metal and understand they take lots of pressure and use lots of hp. So I think I’ll just carve up the old Madison’s when I need something similar, maybe boring bar or whatever. Any reason I should refurb the old Madison’s including trying to find inserts that’ll work?

 

[magneticanomaly]

Looks like inserts are available, heckuva lot cheaper than big twist drills.

 

[Cannonmn]

Thx, yes we’ve got twist drills for any dia up to 3”, and I know there are machinists who strongly prefer spade drills over twist drills, not sure of the advantage unless it is cost of replacing inserts is less than having twist drills resharpened? Maybe someone who has used twist, spade, annular, boring will comment on advantages of the choices for drilling mild steel, we don’t do aluminum too often.

 

[Ben]

I have used large twist drills, but since I started using annular drills that is my go to for larger holes. I have an adapter for the milling machine which is where I use them. I also use the mag drill with them. I use a boring head for precise holes. No experience with spade bits other than wood bits.

Ben