Flat bit

[GrahamRounce]

What is the little hole for in a flat drill bit?

 

[skeetstar]

I use it to hang it on a nail.

 

[Argus]

Ventilation?

 

[powertools]

https://www.wonkeedonkeetools.co.uk/spade-bits/what-are-the-parts-of-a-spade-bit

 

[MARK.B.]

Well I never knew that, I would never in a month of Sunday's have thought of the actual ( other than hang on nail ) intended use by myself , but I would think the temptation to leave the drill hanging if working alone would be hard to resist

 

[Cirks]

Not surprisingly, I had no idea about the cable hole. However, in reality how often does anyone think it’s used? Vast majority of the time if you can see the drill bit you’re going to see the hole from wherever it’s finished up. Most flat bits would be used where bigger than a standard wood drill bit therefore the hole won’t be hidden from view! Anyway, a pull cord/cable inserted from the side being drilled from would also be easily visible

 

[Phil Russell]

Maybe it is there to balance the rotation as the bit is being used? So that the bit does not wobble too much.
Cheers, Phil

 

[Robbo60]

How big a cable??

 

[Cirks]

How big a cable??

Pull cord attached to cable

 

[Phil Pascoe]

Maybe it is there to balance the rotation as the bit is being used? So that the bit does not wobble too much.
Cheers, Phil

They're on centre.

 

[Gavlar]

I'd always assumed some sort of expansion or vibration relief, like the holes on circ saw blades, without really thinking too hard about it.

 

[StephenArfer]

I always assumed it was part of the manufacturing process. To allow positive location in the jig used to secure and positively locate the bit during finish grinding of the cutting edges

 

[Rorschach]

I always assumed it was part of the manufacturing process. To allow positive location in the jig used to secure and positively locate the bit during finish grinding of the cutting edges

That's what I thought as well.

 

[Jonzjob]

I thought that it was to make it a bit lighter

 

[Droogs]

I thought it was for a tommy bar to gt you started

 

[Phil Pascoe]

Horrible things anyway, with or without a hole.

 

[toolsntat]

Lifetime limiter.
Can't have em lasting for ever.....
Only so many sharpens until you hit the hole.
Cheers Andy

 

[Richard_C]

I have made use of the hole. Needing a one off deep hole on a turned cylinder, precision not required, I started with the spade bit in the tailstock chuck as normal. Got as far as I could, needed a few more cm, ah... Long screw bit holder in chuck, bit in holder.... but spade bit will jam at bottom and I'll never get it out.... Ah, bit doesn't rotate so can thread a bit of garden wire through the handy wonder-what-it's for hole so I can yank it out. So I did and it worked.

 

[GrahamRounce]

Thanks! I'm sceptical of the cable pulling, slightly less so of the 'part of the manu process'.
If it was enlarged a little, it could be used to bolt a depth stop to the bit, if you needed one, but only up to the position of the hole, obvs. (Easier to make your own hole further back, as I've done before now.)

 

[Inspector]

Spade bits are often used with extensions of 12" or more on them to drill up through floors etc. Then someone on the other side can attach the pull to it and draw it back through the hole. An electrician will have the cables to pull wire with and not need it but there are times when it can be handy.

Pete