how to drill a round hole!

[johnakay]

saw this on another forum....

 

[WorkshopChris]

Would like to see the rag trick with 2 identical bits of material to start with.
The 2nd bit had a good hold in the vice, that 1st bit gave in as once the hole went through the side wall was to thin for the pressure the jaws were exerting.

 

[rtbcomp]

What's the science behind that then?

 

[rtbcomp]

Would like to see the rag trick with 2 identical bits of material to start with.
The 2nd bit had a good hold in the vice, that 1st bit gave in as once the hole went through the side wall was to thin for the pressure the jaws were exerting.

The bend in the 2nd bit would give it greater strength too. You could tell by the noise that the 1st one wasn't drilling true.

 

[atomant48]

Would one of those step/cone drills help? I have good success with them but never tried anything with such a small edge left after the hole is drilled.

 

[p0689109]

Where was the coolant flow?