Ancient Time Honored Skills

First, just to prove that progress IS being made, here are the three completed aileron hinges.

Three more to go.

But what I really want to talk about today is, what seems to be, the lost art of sharpening drill bits.  This interest was brought on because somehow I have managed to misplace the drill point gauge that I have had since I don't remember when.  At least 40 years.

I grew up believing that, if you wanted to drill holes in things, you needed a small assortment of tools.  The first being some means of turning the drill bit, such as a hand drill or drill press. Back in those days you usually had an "egg beater" style of hand drill, a 1/4" electric drill, and, if really affluent, a drill press.  Obviously, you needed drill bits, too.

But nothing stays sharp forever, so two other tools, a bench grinder and a drill point gauge are necessary.  As observed above, I lost my old faithful drill point gauge somewhere along the way. 

Being the naive type, I trotted down to my local hardware store, which has a very fine inventory, and got blank looks when I asked for a drill point gauge.  Nobody, but nobody, in the store had heard of such a thing and had never heard of anyone sharpening drill bits.  Everybody just assumed that dull bits got thrown away and new ones purchased.  Unbelievable.

On a hunch, I stopped at the local NAPA on my way home.  The gentleman at the counter (with gray hair) at least had heard of a drill point gauge.  However, they did not have one in stock.  The best he could do was offer to sell me a dedicated (made in China) drill sharpening machine at something well north of $100.  For sharpening drill bits?  Give me a break!

I finally found a drill point gauge at L.G. Isaacson.  But first, a brief description on how drill bits are sharpened.  A good bit has four characteristics:

1.   It is straight. That is set at the factory and you can't change it.
2.   The cutting lips are sharp and are raked back from the point at 59 degrees.
3.   The bit slopes back from the cutting lips to clear chips.
4.   The point, where the two cutting lips come together, is centered.

A bit gets dull when the cutting lips are no longer sharp. The process of returning them to a good sharp condition is, with a little practice, very easy.

You hold the bit, as shown below,  with the cutting lips at a 59 degree angle to the wheel, parallel to the floor.

Note that I have drawn a line, with a Sharpie, at a 59 degree angle to help me keep the bit aligned properly.  Just touch the bit to the wheel and then give it a slight clockwise twist while lowering the far end of the bit just a tiny little bit. Flip the bit over and do the same to the other side.

If you did it correctly, and evenly, your lips will be sharp, the rake will be correct, the angle of the lips will be 59 degrees, and the point will be centered.  How do you know if you got it right?

Why with the point gauge, of course.

Here you can see how the point gauge is used. The angle on this bit is slightly off, so it needs to go back to the grinder.  To check the centering of the point, just compare the two sides of the drill to the number etched on the gauge.  You will note that the point on this bit aligns with the "5" line on the gauge.  The other side should do the same (it does).

The final test is to drill into a piece of mild steel. At the right speed and feed rate you should get nice curly chips.  If not, back to the grinder.

See, that is not so difficult.  And you get years of use out of a drill bit instead of just a few holes.