sharpening brace bits

[marcros]

I wanted to try something from the Anarchist's Design book, which requires a tapered reamer. I found a cheap one on ebay (although looking at it it might be a bit small for the second project I had in mind). I am waiting for these to arrive, but when they do how and what parts do I sharpen?

Am I right in thinking that I have bought a tapered reamer, a couple of small spoon bits, a shell bit and a spoon bit with a lead screw?

 

[AndyT]

Nearly. Terminology is a bit loose, but given that there is a specialist bit used by chairmakers that you could pick up water in, let's reserve the name Spoon Bit for that sort.
So I'd say to expect a reamer, two nose bits, a shell bit and a gimlet bit.

The reamer and the shell bit cut on the leading long side. It's easiest to just lay a fine file flat across both long edges and file them both flat together. Remove any burr from the outside but don't file away any of the outside of the cylinder.

Same for the nose bit but most of the work of that one is done by the little turned over tab, which can be delicately sharpened on the inside, a bit like the spur of an auger.
Gimlet bit is similar to the shell bit for sharpening.

 

[marcros]

ah ok. that makes sense because when I looked for spoon bits they were much bigger.

The nose bits, shell bit and gimlet bits- are they different variations for the same purpose, ie generally making a hole? Or do they have particular uses for the different types?

 

[AndyT]

The nose bits, shell bit and gimlet bits- are they different variations for the same purpose, ie generally making a hole? Or do they have particular uses for the different types?

Good question. I don't think it's true to say that newer types are better.

I think the survival of older types probably had more to do with ease/cheapness of manufacturing.

But with so many variables of timber type, grain direction, size of hole, closeness to edge, speed, sharpness etc there must be some cases where picking one sort over another brings a big improvement. I have tried out all the different types I have and they all work, but I can't remember enough to construct a chart, sorry!

 

[marcros]

the bits arrived yesterday along with a Stanley brace and Stanley eggbeater drill so I had a chance to have a look, but only some low quality quickly grown softwood offcuts to hand. The timber was far from ideal even for testing.

they all drilled a hole successfully. the far side of the hole resulted in a lot of tear-out but that may have been a number of things. The one with the screw on the end (gimlet bit?) was prone to splitting thin wood, but it is a huge screw to drive into the wood so entirely unsuited to that task. It was better in the thicker piece.

I also used the tapered reamer. I gave it a quick tickle up on a diamond plate, but may need to get a slip stone to touch up the insides. the straight parts now have a small flat on the top, as they would with using a file, so I am not sure whether it is correct. it feels sharpish but wants a bit more attention starting from a coarser plate or a file as suggested. It did however work on both the thick and thin test piece, although it did seem to tear a bit at the hole. I would expect that a good portion of this was due to the timber though because I noticed it on the part between growth rings. I think I also drilled the starting hole with the gimlet bit so it may have already tried to split to some degree.

The bits all seemed quite slow in performance and slightly harder work when compared to auger bits. I hadn't sharpened them, but they felt ok to my finger. I didn't measure them, they were smaller than I expected from the picture and would fall into the size range where I would likely use a drill rather than a brace.

 

[AndyT]

Ah yes, you could add depth of hole and thickness of wood to the list of variables!

And fwiw, I have made more splits than holes when trying to use a gimlet bit.

 

[Boringgeoff]

The sharpening method Andy laid out in #2 is how I would do it. To reduce tear-out on the exit, try clamping another piece of wood behind and you may also find boring a skinny pilot hole helpful as well.
Cheers,
Geoff.

 

[MikeG.]

Good question. I don't think it's true to say that newer types are better.

I think the survival of older types probably had more to do with ease/cheapness of manufacturing.

But with so many variables of timber type, grain direction, size of hole, closeness to edge, speed, sharpness etc there must be some cases where picking one sort over another brings a big improvement. I have tried out all the different types I have and they all work, but I can't remember enough to construct a chart, sorry!

I'm pretty sure they're all for drilling into end grain, other than the reamer, of course. They look like small versions of the pipe-making augers that were used to hollow out elm logs to make riser pipes for hand pumping water out of a well.