[TheForge] Drill Doctor

[theforge@mailman.qth.net]

Agree with all that. it's just not that hard to sharpen drills by hand. 
At least down to 1/4" and you can buy a lot of 1/8" drills for $100.  
Somewhere along the way drill sharpening got the same sort of mystique 
as forge welding. Ask your local machine shop guy for a quick lesson. 
After being shown how it just takes a bit of practice.

One thing that is true is that it's hard to freehand sharpen a drill 
and have the hole be right on size. This isn't much of a concern in a 
blacksmith shop. Take a look in your Machinerys Handbook. There is a 
chart of "probable hole sizes" using various size drills. Drills are 
roughing tools in a machine shop and not really meant to drill right 
on. That's what reamers are for (or a boring bar). If your hole has to 
be on size use several small drills first. A good policy anyway when 
drilling large holes.

Bob
__________


On Sunday, November 16, 2003, at 06:37 PM, Kevin Donahoe wrote:

> Roger,
>
> I know you didn't ask, but that never seems to stop me :)... I took a
> machine shop class 15+ years ago and the first night there, there were 
> two
> fellows trying to sell their drill doctors.  20 minutes later I found 
> out
> why as it was one of the first things we learned in the class.  With a
> decent grinding wheel or belt sander, it doesn't take much to sharpen 
> one.
> Using a drill gauge by General Tool for a few bucks, you can get them 
> just
> short of perfect.
>
> The technique, as I was taught was very simple.  It's easier to learn 
> using
> a larger bit.  Hold it with both hands, dominant hand in front, near 
> the
> wheel, week hand at the heel of the bit.
>
> 1-Hold the drill bit at 52*? horizontal at the horizontal tangent of 
> the
> wheel, so your grinding on the plumb surface.
>
> 2-Make sure the cutting edge is level/horizontal, and the length of 
> the bit
> is level, too.  I often rest my ring or middle finger on the rest that 
> runs
> in front of the wheel to steady things.
>
> 3-With light pressure on the wheel/belt, drop your hand holding the 
> heel of
> the bit straight down. DON'T TWIST! just keep the cutting face flat 
> against
> the wheel/belt as you drop the heel.  Keep a steady pressure and the
> trailing surface will have a bit more relief than the cutting edge.
>
> 4-Turn it 180* and repeat.
>
> It's more important that each leg of the bit is even length and angle 
> with
> the other than they are the exact 52*.  This can be judged fairly 
> easily by
> looking at the point, end-on.  With the drill gauge it's real easy to 
> tell.
>
> Clear as mud? :)
>
> In fact, there are a few other points for sharpening different 
> materials
> that make a job easier, ie if it's  cast iron, make the point more 
> flat than
> the 52*, if it's brass, lightly touch the sharp edge of the drill to 
> make it
> a chisel bit, and it won't bind.
>
> Kevin