[modeleng] Re: Piloted "D" Bit

Al

Not when I've made 'em.  Can't see why you think it should.

If we are talking counter-boring tools they are not usually "D"-bits.

A counter-bore bit is usually made by filing/grinding each side of the
material, so that the end looks like a fat flat-bladed screwdriver with a
round hole in the middle.  Each of the end cutting edges is then given
clearance appropriate to the material being counter-bored.

Easier to describe with a picture !

If you really want to mimic commercial piloted counter-bore bits, you can
turn down the pilot pin so that the small diameter is inserted into the bit
and the larger section forms the actual pilot.  In practice, they work
perfectly well without going to this trouble.

Andy

-----Original Message-----
From: modeleng-bounce@xxxxxxxxxxxxx [mailto:modeleng-bounce@xxxxxxxxxxxxx]
On Behalf Of Allen Messer
Sent: 28 July 2007 00:41
To: modeleng@xxxxxxxxxxxxx
Subject: [modeleng] Re: Piloted "D" Bit

Thanks for all thge advice---I had not thought of a
separate pilot.  One question though: does the part of
the pilot that mates with the flat on the "D" bit have
to be filed to half its diameter?

Al
--- Patrick Coppens-Marian Lynch <develop@xxxxxxxxx>
wrote:

> Al,
> Just a thought.
> Drill a hole were the pilot should be,slightly under
> the size of the pilot.
> Before quenching it, insert pilot in the hole
> (separate piece)
> The pilot will be held by the contraction of the
> metal, and will not 
> warp, as it was never heated...
> 
> Cheers
> Patrick
> 
> Allen Messer wrote:
> 
> >I need to make a "D" Bit with some extra reach to
> it
> >in order to counter-bore some Allen head bolt seats
> in
> >a hard to reach place.  I plan to make it out of
> >Silver Steel and harden it.  How  it is possible to
> >make one wherein the "pilot" won't warp during the
> >hardening process?  I've tried it a couple of times
> >and the pilot wants to warp when quenching out. 
> TIA
> >
> >Al Messer
> >
> >
> >     
>
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