Sharpening brace bits

[Ken Masco]

I just acquired my first brace and bit set on Ebay. Seems as though someone attempted to sharpen the bottom edges although with a pretty rough file or stone. The worm tip seems fine on all of them. I tried a few bits on some cherry stock and they cut the first 3/16th or so fine then they bog down and are hard to crank. Question; are there sharpening services that can bring these back to full function? If I have to sharpen them myself is there anyone out there that has experience and advice?

[David Weaver]

Buy an auger bit file. There are probably a few places that sell them - TFWW is one.

The auger bit files have purpose designed safe sides and a shape that will allow you to sharpen the bevel on the bits and touch up the wings (if they are dinged up or dull) without filing areas you don't want to file.

[Zahid Naqvi]

a few pointers

1. when sharpening make sure you only sharpen/file the top side of the cutting edge. Imagine a bevel down hand plane, if the bevel angle is greater than the bedding angle of the blade the non cutting edge of you plane blade will make contact with wood first and your plane will just glide over the wood without cutting. It's a little hard to describe verbally, but if you have a large size brace bit in front of you when you read this it will make perfect sense.
2. Make sure you lead screw is sharp. The digging in part in a brace is all done by the lead screw, if that is not properly sharpened it will not travel.
3. Since you mentioned previous attempts to sharpen, one thing I have noticed in old brace bits is over enthusiastic sharpeners. Who will file off the last bit of the lead screw such that the area where the screw and the cutting edge overlap there is a little gap which will stump/kam the screw. Once again hard to explain but with a bit in your hand it is immediately noticeable where you should not file.

I have been able to sharpen brace bit using a small diamond file, the one you can use to touch up router bits etc, and needle files to get into corners. I found this guide from Alf (http://www.cornishworkshop.co.uk/bracecleaning.html) incredibly useful, as well as this article (http://www.popularwoodworking.com/woodworking-blogs/chris-schwarz-blog/the-essential-brace-bit) from The Schwarz

[Jorge Rico]

Are the bits designed for soft or hardwood? I'm not sure if this is correct terminology but a "flatter" or "shallower" pitch at the cutting edge combined with fine lead screw threads usually means a bit designed for hardwood. A "steeper" pitch combined with coarser threads in the lead screw is usually asociated with a bit deisgned for softer wood. What you're describing sounds like the behavior of a softwood bit in hardwood.

[Ken Masco]

Thank you Zahid, I'll sit down with the bits and your guidence this weekend.
Jorge, how can I tell if they are for softwood or hard wood? They came in a wooden box that says Navy Auger Bits on the label

[Bill Houghton]

Jorge, how can I tell if they are for softwood or hard wood? They came in a wooden box that says Navy Auger Bits on the label

I'm not Jorge, but I'll offer some thoughts. The lead screw on bits designed for softwood will be significantly coarser than the screw for hardwoods. This is a relative thing, and can be tricky if you don't have examples of both to compare; but the lead screws for softwood will resemble the screw pitch on a regular wood screw, while the screws for hardwood will be noticeably fine in pitch. Further trickiness comes from the fact that there are (relatively rare, in my experience) mid-pitch screws.

Bits with a solid center - it looks like the shank above the twisty part just continues all the way through to the end - are usually designed for softwoods (some folks call these "Irwin pattern" after the company that kind of dominated this particular niche). While this is NOT universally true, Jennings pattern bits (see below) are most often designed for hardwoods.

By the way, Zahid didn't mention one additional sharpening rule: NEVER file the spurs - rounded cutters on the perimeter of the bit "face" that nick the wood as you turn the bit, freeing up the chips for the cutters to remove - on the outside, even to remove filing burrs. These must be the diameter of the bit, or a tad larger, for the bit to work. File the inside only. Any filing burrs will be removed by your first hole.

Jennings pattern bit:
201859 201860

[Jorge Rico]

Bill said it perfectly so I will refrain from adding to his description.

[george wilson]

But,if the spurs are damaged,like turned like fish hooks,you'd have to file them.

[Jim Koepke]

There are a few threads here on SMC with more information about braces and bits.

http://www.sawmillcreek.org/showthread.php?13090-The-Incredibly-Versatile-Sweep-Brace

http://www.sawmillcreek.org/showthread.php?167266-Auger-bit-question

http://www.sawmillcreek.org/showthread.php?131238-A-Bit-About-Augers...

To answer your question:


Question; are there sharpening services that can bring these back to full function?

The cost to have someone sharpen them for you would likely be more than a new set would cost.

I tend to pick up spare bits when I find them at yard sales and such. Those that can be rehabbed go into my extras box.

The first time you hit a hidden nail or screw you will understand why I like to have extras of all my sizes.

jtk