Replies

1. 
   AdamCherubini | Apr 08, 2006 06:53pm | #1

   Sounds like you have shells, not spoons.  A spoon bit would hold water when held level.  A shell bit won't.

   With that out of the way, sharpening is a simple matter.  The profile is usually shaped like a finger nail or turning gouge as you say.  All you need to do is make that edge sharp.  Don't grind it or try to make a concave bevel.  You can usually just hit that bevel with a fine mill file, then clean up the burr with a fine india cone (stone).  You need to sharpen all the way up until the finger nail runs out and intersects the side. The side is not sharpened.  Technically, if you only turn your brace one way, you only need to sharpen half of the bit.  But don't.  Sharpen both sides. to get a precise location, you can ratchet shells and they will walk around a bit.  That's how shells work.

   You'll also notice that the cross section isn't semi-circular.  The concave side might be, but the convex side isn't.  Don't "correct" this.

   Best advice I can offer is not to try to "out smart" your grandfather. He knew what he was doing.  Just hone what you see and try it.  Be prepared to use of the most butt kicking drill bits you've ever used before.  These puppies are blazingly fast, easy to sharpen, can bore at very low angles, and rarely cause breakout.  Shells are a superior boring wood boring technology.  Ditto for center bits.

   Adam

1. 
   AndyE | Apr 09, 2006 01:21am | #2

   Adam, I just picked up a brace and a couple of spoon bits at Garrett Wade in NYC. Haven't had a chance to put them to use yet.So to clarify from your response: Am I correct in thinking that where the spoon bits turn up at the end the shell bits would be "open"? I tried Google-ing shell bits and didn't find much there. If that is the case then it sounds like the the bit uses the corner where the side and the end of the curve meet to do the cutting. "You'll also notice that the cross section isn't semi-circular. The concave side might be, but the convex side isn't. Don't "correct" this."-What is the reason for this shape? I would guess that if is flattened instead of egg shaped it would reduce friction in the hole with the outside of the bit. Without having one to look at that is just a guess.Andy"It seemed like a good idea at the time"

1. 
   AdamCherubini | Apr 09, 2006 03:28pm | #5

   I think you have it right on both counts. I have a pretty extensive collection of these bits. E-mail me off line if you need pictures of this sort of stuff. Its so much easier to understand these things when you see them (or see them working). I routinely demonstrate the use of these bits for Pennsbury's visitors. They are so very peculiar looking and function so well, it helps plant the seed that there were efficient methods of woodwork 300 years ago. Adam

1. 
   pzgren | Apr 13, 2006 01:20am | #6

   Adam, Dave, Andy,

     Very interesting and informative thread. Thanks for the question and for the answers. I learned quite a bit here.

   Thanks again!

   James

2. 
   DCarr10760 | Apr 09, 2006 05:35am | #3

   Hi Adam,

   Thank you very much for the response.  I'll give them a go.

   My plan was to make an 18th century type brace and use these bits (mounted in wood).  But now I am learning to do some blacksmithing and may make center bits instead and keep these for general use.

   Do you know how 18th Century bits were fixed into the wooden tapered shanks so that they wouldn't spin?

   Much obliged,

   David C.

1. 
   AdamCherubini | Apr 09, 2006 03:23pm | #4

   18th c bits are characterized by their "flat tangs". So where modern augers have a square cross section tapering tang which fits the brace's chuck, 18th c bits were roughly rectangular and just tapered in the forging process. The tapers weren't uniform bit to bit. The tangs were then let into tapered woden pads or pods in a similar fashion as tanged chisels are mounted in handles. I start by boring a hole in the end grain using a special bit called a nose bit then enlarge the hole with either larger bits or tiny chisels. They might have burned the bits in- a practice I don't recommend.Center bits are deceptively complicated. Good luck making them. I hope other smiths follow your lead.BTW- we use the term "smith" or "black smith" but this can lead to confusion. No American horse shoeing black smith ever made center bits. Black smiths work iron, typically with some aggrarian interest in mind. The men who made chisels and bits were specialists called "cutlers". There were cutlers in America in the 18th c, but not many and they weren't all that prolific. This is all said just so we don't get the impression that every corner smith could bang out these specialty steel items. The could not and did not. So if you encounter some difficulty, don't feel bad. All that said, I know smiths who have made center bits and they didn't seem to make too big a deal out of it! They say shells and spoons are considerably easier to make!Some people similarly confuse carpenters and cabinetmakers. Its a similar analogy.Adam