----- Original Message -----
From: "Mike Waters" <mikewate@gmail.com>
To: <herbs@vitelcom.net>; "topband" <topband@contesting.com>
Sent: Saturday, August 11, 2012 11:04 AM
Subject: Re: Topband: Radials over a stone wall
> On Sat, Aug 11, 2012 at 9:10 AM, Herb Schoenbohm <herbs@vitelcom.net>
> wrote:
>
>> When drilling in stone to prevent overheating of the drill bit and tip
>> consider using water as a coolant.
>>
>
> You have to be careful doing that. Some types of carbide will instantly
> crack from the thermal shock of cooling too fast. It's better just to
> retract the drill a lot so that the grooves in the drill bit don't plug
> up;
> that's what generates a lot of heat.
Cleaning out the grooves and hole on a regular basis is all Ive ever done
and the bit is over 20 years old and still does the job. Its easy to tell
when it needs cleaning as the progress slows down.
Carl
KM1H
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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