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Re: [TowerTalk] Drill bits

To: "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] Drill bits
From: "Roger (K8RI)" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Wed, 24 Mar 2010 01:34:06 -0400
List-post: <">>

Guy Molinari wrote:
> Hi all,
>     I don't know why this is so hard.   I'm trying to drill out some hole on 
> some 3/8" steel plates that I'm going to have galvanized.   I bought a 13/32" 
> drill bit and it worked great for about 10 holes or so.   The problem is that 
> I have about 140 more to go.   Any recommendations on a good quality drill 
> bit?   
Others have covered much of this already:
Use good drill bits...purchase at least a half dozen. With 140 holes I'd 
plan on a dozen of each size from the pilot hole to finished hole.

Drill a pilot hole when the final hole will be relatively large.
Actually a pilot hole or moving up in steps is good most any time as the 
finished hole can be made quite clean .
If galvanizing, don't forget to break the edges of the holes (both sides)
Look up the proper speed for the size bit being used and the material 
it's being used in.
I no longer remember the speeds but I know what looks right and haven't 
burned up a bit in years.
Sharpening skills?  Purchase a "Drill Doctor", They really work and do a 
good job with little skill required from the operator and the learning 
curve is rather shallow ...and short.
Keep the bit(s) sharp.
As to that speed, a 13/32" bit should run slow enough you aren't going 
to want to drill many with a hand held drill, or you'll be smelling 
burnt insulation. Running at the proper/slow speed will likely overheat 
the motor and I can testify to having burned up the largest, variable 
speed, 1/2" drill motor I had and I'd just taken it out of the box. If 
you are a glutton for punishment and use the T-handle you *might* be 
able to stall one of those. I can, have, and burned it up...literally. I 
felt it lose torque, saw it blowing smoke, and before I could let go of 
the trigger it was blowing flames.  Man that thing did stink! BTW I was 
using a 7/8" bit.  Don't even think about trying one that size unless 
you are in really good shape as you can get hurt.


Roger (K8RI)
> 73,
> Guy, N7ZG
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