What's with thees drill bits?

D

dbb-the-bruce

Dave
H-M Lifetime Diamond Member
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Feb 28, 2019
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508
Acquired tooling.....
I've never seen bits with holes in them like these, can anyone clue me in as to why?
One of the bits as extra relief for the first 1/2" or so.

IMG_3699.JPG
IMG_3700.JPG
 
Let me be the first, Coolant through the drill.
 
I would guess flow through coolant, is there a hole at the other end to add coolant?
 
And I thought I was a smart, observant guy.

I considered it might be for coolant. I attempted to probe the depths of the holes with a piece of 14g copper wire and concluded that the holes dead ended. But duh, never looked at the other end of the shanks.

So yes indeed, fine copper wire follows the holes and lo-and-behold they go the full length of the bits.

Q1: How the hell do they do that? the flutes must get twisted in after the coolant holes are drilled. I always assumed the twist was ground into bits.

Q2: will I ever use these? seems very unlikely. I guess I'd need some sort of way / kit that forces coolant through my spindle. I don't even use coolant for anything yet.

Is it worth keeping them to use without coolant?
 
dbb-the-bruce said:
And I thought I was a smart, observant guy.

I considered it might be for coolant. I attempted to probe the depths of the holes with a piece of 14g copper wire and concluded that the holes dead ended. But duh, never looked at the other end of the shanks.

So yes indeed, fine copper wire follows the holes and lo-and-behold they go the full length of the bits.

Q1: How the hell do they do that? the flutes must get twisted in after the coolant holes are drilled. I always assumed the twist was ground into bits.

Q2: will I ever use these? seems very unlikely. I guess I'd need some sort of way / kit that forces coolant through my spindle. I don't even use coolant for anything yet.

Is it worth keeping them to use without coolant?
Click to expand...

The flutes aren't actually twisted into the bit like a decorative wrought iron railing. Rather they are ground in as in this video:

 
There is a video going around showing a favorite Eastern Country twisting the flutes into Their drill bits. No time to find it right now.
 
projectnut said:
The flutes aren't actually twisted into the bit like a decorative wrought iron railing. Rather they are ground in as in this video:

Click to expand...

Right, as I would expect. So how the hell do they get coolant holes to spiral up with the flutes?
The only practical way I can think of is to drill straight holes and then twist the blank. This could be done before or after the flutes. I'd think that if you twist a blank, it would need to be heat treated to remove any strain after. The flutes could be "roughed" into the blank shape, ground later or just ground later.

(sometimes I think to hard about these things)
 
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