In Praise of the Centre Bit.

[AndyT]

It's maybe worth noting too that the older type of centre bit was still listed in catalogues in the 50s (which I feel isn't really very long ago) - and was cheaper than the 'fast cutting' sort. I guess it was the rise since then of the small electric drill, as the first power tool for any diy-er, that killed off the demand for braces in general and the bits to go with them. Hence compromises like the cheap flatbit, burning its way through anything in its path...

 

[Jacob]

Flat bits are excellent but they can't do what a centre bit can do (with or without lead screw) - which is to reverse the hole i.e. to wait for the point to just show and then drill from the other side.

 

[Andy Kev.]

Flat bits are excellent but they can't do what a centre bit can do (with or without lead screw) - which is to reverse the hole i.e. to wait for the point to just show and then drill from the other side.

What I'm looking forward to finding out, once I've got them sharpened up, is whether or not the fact that they have lead screws means that they will split thinnish pieces of wood (as my normal augur bits do).

 

[Cheshirechappie]

Flat bits are excellent but they can't do what a centre bit can do (with or without lead screw) - which is to reverse the hole i.e. to wait for the point to just show and then drill from the other side.

What I'm looking forward to finding out, once I've got them sharpened up, is whether or not the fact that they have lead screws means that they will split thinnish pieces of wood (as my normal augur bits do).

Must admit, I don't know the answer to that one, either. The 'Renaissance Woodworker' video matches my experience with the older sort, in that they are much less prone to splitting thinner stock than twist augers (I wouldn't go so far as to say that they totally eliminate any possibility of splitting). It'll be interesting to hear any reports of performance of the newer type of centre bit with leadscrews.

 

[Cheshirechappie]

I think it is noteworthy that (prior to the dominance of auger bits) sets of brace bits are invariably (IME) mixed in type, as you say. It implies that the buyers knew, understood and exploited the strengths and weaknesses of each type, and used them appropriately.

BugBear

The Lost Art Press publication of 'The Joiner and Cabinetmaker' illustrates a Melhuish catalogue entry from 1912, showing a set of 36 bits. It consists of:

12 old-type centre bits, 3/16" to 1 1/4"
2 turnscrew bits, one forked
6 countersinks (2 each flat, rose an snail, 1 off 1/2" and 5/8" of each)
5 shell bits, 1/8" to 3/8"
5 nose bits, 1/8" to 3/8"
2 sash bits, 3/16" and 1/4"
3 rimers, 1 each square, half-round and hollow
1 Jennings pattern twist auger, 1/2"

Available in Black, price 10/6, Bright price 12/-, or Straw Coloured price 13/6. [That's shillings and pence - today those prices would be 52 1/2p, 60p and 67 1/2p. I wish!]

Interestingly, no bit roll is mentioned. Was the purchaser expected to make their own storage arrangements, or stung for the roll as an extra, one wonders?

I think that would be a fairly typical general joiner's kit; cabinetmakers and other specialist trades would have slightly different requirements. The Jennings auger is for dowelling, the rimers and countersinks for fitting screws to ironmongery and brassware (in the days before better standardisation of sizes), and the other bits for general drilling. Interesting that the sizes of shell bits and nose bits duplicate each other - it may be that one type or the other was preferred for different tasks, such as through holes, long-grain drilling etc. The sash bits are clearly for one main purpose. The centre bits are for larger, shallower holes, and the fact that the range of sizes is more comprehensive suggests that they were expected to do the bulk of drilling work. Also worth a mention is that very small holes would be produced by bradawls or gimlets, both non-brace tools. Most craftsmen would have at least two or three, and perhaps several sizes of both.

You don't come across many intact sets; hardly surprising, really. Most kits suffer wear and tear, losses and breakages over time (especially the smaller sizes of bit), and subsequent additions. I suspect also that most craftsmen would not have bought sets, but would have spread the cost by purchasing individual bits as the need arose, and made up their sets that way. That seems reflected in the contents of kits that come up for sale today, anyway.

The 1938 Marples catalogue uploaded to Toolemera by AndyT also lists sets of 24, 36 and 48 bits. I suspect they were available long before 1912, and some while after 1938.

 

[AndyT]

It'll be interesting to hear any reports of performance of the newer type of centre bit with leadscrews.

Here we are then. One manky bit of thin softwood from the scrap box, held down to a backing board, and a 3/4" flatbit in a sixpenny brace:

Even right by the end, there is no splitting effect. (A bit of short grain has detached, but the wood is not split.)

Let's cut the end off and try again, using a bit with a leadscrew.

Going once:

Going twice:

Gone!

I think the difference is clear. For an encore, a 1 1/4" centre bit in just enough wood:

Despite the wood already being split, a tidy hole is made.

To be fair, I also tried drilling into a stronger bit of 2x4, away from the edge, and found that the fast cut bit worked well, and was easier to use, as I did not need to press down. Indeed, the old style bit tended to choke up when it was about 3/4" down and I needed to remove it and pick resinous residues off the centre spike. I'd say that using the fast cut bit was much like using an auger bit, but potentially easier to manage than something 9" long and cheaper to buy (if bought new, back when they were easily available).

 

[Cheshirechappie]

Interesting! Thanks for that, Andy.

The conclusion is that neither 'older' nor 'newer' centre bits could definitely be said to be better. Both have pros and cons. In fairness, the need for large holes near the end of thin stock is not an everyday problem, though if the occasion did arise, having some older bits to hand would be a decided advantage. I suppose the best answer is to have some of each, especially if you drop on a few bargain assortments on Ebay or carboots!

PS - Nice little braces, those sixpenny jobs, aren't they? For smaller work that doesn't need too much grunt, I rather prefer mine to the heavier Stanley 10" ratchet job. Changing bits is faster, too.

 

[Andy Kev.]

Interesting! Thanks for that, Andy.

The conclusion is that neither 'older' nor 'newer' centre bits could definitely be said to be better. Both have pros and cons. In fairness, the need for large holes near the end of thin stock is not an everyday problem, though if the occasion did arise, having some older bits to hand would be a decided advantage. I suppose the best answer is to have some of each, especially if you drop on a few bargain assortments on Ebay or carboots!

PS - Nice little braces, those sixpenny jobs, aren't they? For smaller work that doesn't need too much grunt, I rather prefer mine to the heavier Stanley 10" ratchet job. Changing bits is faster, too.

I had to laugh when I read that because it suddenly is an everyday problem when you decide to make a spaghetti measurer. I bought a book of ideas for making things from offcuts (name of author escapes at the moment and I'm not at home as I type) and therein is a spaghetti measurer. I decided to make one using only hand tools and the Augur for the biggest hole split some 3/8" American Walnut. So I ended up cutting some 1" walnut without problems and resawed it. Hence my new-found interest in centre bits.

Thanks to AndyT for the experiment. I have a cunning plan for eliminating the split with the screw type which I've just bought. Once my slip stones arrive and everything is sharp, I shall report.

Incidentally, for those who may be interested, here's a link to a German bloke's website where he talks about bits:

http://www.holzwerken.de/werkzeug/bohre ... eler.phtml

If there are any parts of it which are of particular interest, let me know and I will translate.

 

[undergroundhunter]

Would it not help to start the hole for the lead screw with a birdcage awl? This would possibly remove some of the wedging action caused by the lead screw. I haven't tried it, its just a thought.

Matt

 

[nanscombe]

You're almost getting to the point of having to drill a pilot hole for the lead screw, like a normal woodscrew :lol:

 

[Sheffield Tony]

When chairmaking it is not at all uncommon to need to drill a hole near the top of a leg, with a drill bit up to 1/2 the size of the wood itself. A pilot hole - I used 3mm for a 5/8 Irwin pattern auger - makes splitting caused by the leadscrew a lot less likely.

 

[Cheshirechappie]

I had to laugh when I read that because it suddenly is an everyday problem when you decide to make a spaghetti measurer. I bought a book of ideas for making things from offcuts (name of author escapes at the moment and I'm not at home as I type) and therein is a spaghetti measurer. I decided to make one using only hand tools and the Augur for the biggest hole split some 3/8" American Walnut. So I ended up cutting some 1" walnut without problems and resawed it. Hence my new-found interest in centre bits.

Thanks to AndyT for the experiment. I have a cunning plan for eliminating the split with the screw type which I've just bought. Once my slip stones arrive and everything is sharp, I shall report.

Incidentally, for those who may be interested, here's a link to a German bloke's website where he talks about bits:

http://www.holzwerken.de/werkzeug/bohre ... eler.phtml

If there are any parts of it which are of particular interest, let me know and I will translate.

Laugh? Well - yes - you can't do anything else, can you really! Absolute proof that in general, it's not a good idea to generalise!

Good luck with the spaghetti measurer. Let us know how you get on; it's bound to add to the general stock of knowledge.

Thanks for the link, too - Google Translate did a pretty fair job, except for the technical terms, but it was fairly easy to spot the dodgy translation and sustitute the proper word.

--------

Just a thought about using a pilot hole to prevent the leadscrew of a twist auger (or new-style centre bit) splitting stock - that will stop the screw pulling the bit into the work, so there will have to be a bit of axial force applied to the brace to get it to cut. That may not be such a bad thing, since the operator can determine the rate of cut, rather than having it set by the lead of the screw. For larger holes, which take quite a bit of grunt to drive at the rate set by the screw, that could be a definite advantage, especially in harder woods.

 

[nanscombe]

When drilling a pilot hole for a woodscrew you make it smaller than the actual screw so although there is less material to act as a wedge, and split the wood, there is still enough for the thread to bite into otherwise the screw wouldn't hold.

I would imagine that the lead screw would be the same.

 

[Corneel]

This thread was the inspiration for me to finally sort my small collection of centerbits. Mine really only fit in my sixpenny brace (lovely name), because they don't have a square taper but a flat one. I had to file some of them to make them fit better, but that's sorted now. All bits sharpened and I even made some holes in a block of wood for storage.

Nice bits, but they are slow! But it is fun to be able to run that large 1 5/8" one with such a small brace.



No idea really if I will ever use them...

 

[Andy Kev.]

I had three goes with my newly sharpened 1 1/2" bit and split three bits of wood and that despite having drilled pilot holes. I reckon two things: a. the pilot holes were'nt quite big enough i.e. they might be need to be as big as the core of the thread where it is thickest at the top and while I got the cutting part of the bit to be seriously sharp, I couldn't get the scoring element more than routinely sharp. That's obviously a weakness of technique on my part but I wonder if inadequate scoring could contribut to splitting. The wood was very dry American cherry about 3/8" thick.

 

[Jacob]

I blame the wood - too thin. These bits are for bigger stuff. If you want 1 1/2" holes in thin stuff it'd be better to do it through a thick piece and then slice it up. And you shouldn't need pilot holes.

 

[Phil Pascoe]

As an aside - a spaghetti measure is pointless, every time you find the right sized measure, someone will buy spaghetti of a different length.

 

[Cheshirechappie]

I had three goes with my newly sharpened 1 1/2" bit and split three bits of wood and that despite having drilled pilot holes. I reckon two things: a. the pilot holes were'nt quite big enough i.e. they might be need to be as big as the core of the thread where it is thickest at the top and while I got the cutting part of the bit to be seriously sharp, I couldn't get the scoring element more than routinely sharp. That's obviously a weakness of technique on my part but I wonder if inadequate scoring could contribut to splitting. The wood was very dry American cherry about 3/8" thick.

I think I'd try a pilot hole virtually the same as the largest diameter of the centre point. That would eliminate the wedging effect of the taper point. The problem would be holding the drill steady enough to get the outer spur to start cutting a true circle; if that circle could be marked out and 'started' (dividers with a sort of cutting gauge knife filed on, maybe, or a sort of very short trammel made up from a scalpel blade and a panel pin), you'd stand a chance.

Sadly, this is one instance when the 'old sort' centre bits would be in their element - the centre pin working like a birdcage awl cutting the fibres rather than wedging through them.

 

[Jacob]

I had three goes with my newly sharpened 1 1/2" bit and split three bits of wood and that despite having drilled pilot holes. I reckon two things: a. the pilot holes were'nt quite big enough i.e. they might be need to be as big as the core of the thread where it is thickest at the top and while I got the cutting part of the bit to be seriously sharp, I couldn't get the scoring element more than routinely sharp. That's obviously a weakness of technique on my part but I wonder if inadequate scoring could contribut to splitting. The wood was very dry American cherry about 3/8" thick.

I think I'd try a pilot hole virtually the same as the largest diameter of the centre point. That would eliminate the wedging effect of the taper point. The problem would be holding the drill steady enough to get the outer spur to start cutting a true circle; if that circle could be marked out and 'started' (dividers with a sort of cutting gauge knife filed on, maybe, or a sort of very short trammel made up from a scalpel blade and a panel pin), you'd stand a chance....

If you are having to do all that it's simply the wrong tool for the job. Unless you are desperate and have no choice then you have to struggle!

 

[Phil Pascoe]

Yes. Just use a forstner and have done.