Thread: Shaping chair seats

Originally Posted by Woodwould

Ideally the legs should be a snug fit for at least 1/2 to 2/3 of the sockets before the sockets taper outwards very slightly at the top. In effect, the tops of the legs then become dovetailed into the seat and should never budge.

Make sure when you insert the wedges that they are situated at right angles to the grain of the seat. Otherwise the wedging action could split the seat.

Woodwould,

what method is used in tapering a socket, do I just file away?

Zelk

If I could indulge you just for a moment. There are two principle methods of attaching legs to solid seats:

1. Blind tapered sockets (wider at the bottom) are bored in the underside of the seat with a special (7 degree?) taper bit. The tops of the legs are turned to match the tapered sockets and friction (and a very little glue), hold the structure together.
2. Cylindrical tennons on the tops of the legs protrude through nominally parallel through-sockets in the seat and are wedged from above. The parallel sockets are often just left as is by the uninitiated, but the best solution is to taper the tops of the sockets so the wedged tennons flare out, thereby firmly locking the legs in place.
   Because the wedges are situated at 90° to the seat's grain, the flaring of the top of the sockets need only affect the area of the sockets that the wedges will force the sides of the tennons into.
   
   Therefore, and to finally answer your question, a half-round rasp is a good choice of weapon to carry out the flaring with.

Originally Posted by Woodwould

If I could indulge you just for a moment. There are two principle methods of attaching legs to solid seats:

1. Blind tapered sockets (wider at the bottom) are bored in the underside of the seat with a special (7 degree?) taper bit. The tops of the legs are turned to match the tapered sockets and friction (and a very little glue), hold the structure together.
2. Cylindrical tennons on the tops of the legs protrude through nominally parallel through-sockets in the seat and are wedged from above. The parallel sockets are often just left as is by the uninitiated, but the best solution is to taper the tops of the sockets so the wedged tennons flare out, thereby firmly locking the legs in place.
   Because the wedges are situated at 90° to the seat's grain, the flaring of the top of the sockets need only affect the area of the sockets that the wedges will force the sides of the tennons into.
   
   Therefore, and to finally answer your question, a half-round rasp is a good choice of weapon to carry out the flaring with.

With the second method, do you glue the tenon and wedge?

Zelk

Originally Posted by zelk

...do you glue the tenon and wedge?

Yes, both the tennon and the wedge. Sorry, I ommitted that little detail.

Zelk - I should have explained myself better. One of the 'standard' ways to fit legs coming through the seat is to ream the leg hole in the seat slightly tapered (from above). You make a saw-cut in the top of the leg (about 2/3rds of the depth of the seat). Some people drill a hole through the bottom of this saw cut to reduce the risk of the leg splitting beyond that point - probably overkill if the BOTTOM of the leg is a snug fit, which it should be. You then size a wedge which, when driven into the cut, expands the top of the leg & nicely fills the gap, thus locking the leg in place very firmly. Same principle as the wedged through-tenons on well-made doors. I've seen 150 year old chairs assembled this way, without so much as a spot of glue, & those leg joints looked as good & tight as on the day they were made!

It's hard to see from the pic if wedging would have filled the gap, in your case, but you could try it with some scraps & see how it works - it's the easiest wedging method of all, really. There are a few other tricks like "fox-wedging" where the leg is assembled into a closed socket. You remove a bit from the bottom of the socket, cut the leg as for the open joint, then size the wedge so that as you drive the leg home, it expands the end just enough to lock the leg very firmly in place. Get it right & it's magic, but get it wrong, & you have either a loose leg (not so bad as long as you can pull it out & try aagain) or you split the seat by overdoing it (or orienting the wedge to the seat grain in the wrong direction)....

In most windsor designs I make, I use simple, closed sockets for the legs. The danger with these is that very rough use can punch the legs through unless the top of the leg fits snugly against the bottom, which is quite hard to do, actually. I always make stretchers overlength enough that I have to flex the legs very hard to get them in place (ever wondered why they're called STRETCHERS?) Once popped in place, they hold themselves, and hold the legs firmly in their sockets at the same time.

Depending on the design of the leg, & how it flexes under load, it it may need no glue for any of the undercarriage joints. If all of the leg flexing under the weight of the occupant occurs below the stretcher joint, it can remaain unglued, safely. I picked up this point gazing at some very old chairs one day, after noting how they were slightly 'springy' when sat on. These chairs were also probably assembled with legs less 'dry' than the stretchers, too, which was another common 'trick' used by chair makers. The stretcher holes were drilled with spoon bits that make a hole slightly larger internally, so that when the very dry tenon (dried to near 0% MC by heating in hot sand) swelled a bit as the leg dried & shrank, you got a very sound, locked joint. I don't own a spoon bit, & would like to try the technique one day, but even without it, I still use little or no glue when assembling the undercarriage of most chairs. Once it's all in place, it can be darned difficult to get it apart again - DAMHIK!

In my view, through joints are overkill on most chairs, but necessary on anything stretcherless like your stool. I'm a questioner - I constantly ask myself why things are done the way they are - is it tradition (in which case is there a good reason for the tradition) is it simply for effect, or does it serve no purpose other than the maker thought it should be domne that way? You see examples of all of the above all the time. So I experiment & try different things just to see - (sometimes with disasterous results, of course! ) but all good fun.

Sorry - a long rambling reply to a simple question!!

Woops - the conversation between you & WW went on while I was replying, so apologies for the duplication!

There, you have a slight difference of opinion re glueing, but that's waht life's aall about!

And yes - tapering the top of your leg holes with a coarse round rasp is the way if you don't have a reamer.

Cheers,

Originally Posted by IanW

The stretcher holes were drilled with spoon bits that make a hole slightly larger internally...

I'm aware of the shrinkage effect of unseasoned sockets grabbing well-seasoned tennons, but I haven't come across the holes you describe. How are the holes larger internally (I presume you mean bell-shaped), do you think the chairmaker wiggled the bit around as he was boring the hole? How have you witnessed this?

I always glue Windsor type joints - not in the same fashion that I swab glue in mortice and tennon joints in other furniture forms, but I glue them with thin glue as much to swell the fibres as anything else. Wedges have been known to back out and actually fall out completely, so some glue on those doesn't do any harm either.

Originally Posted by Woodwould

I'm aware of the shrinkage effect of unseasoned sockets grabbing well-seasoned tennons, but I haven't come across the holes you describe. How are the holes larger internally (I presume you mean bell-shaped), do you think the chairmaker wiggled the bit around as he was boring the hole? How have you witnessed this?

WW - take a look at these:

http://www.thebestthings.com/newtools/clifton_bits.htm

As I said, I've only read about the method & seen the joint cut through at a woodshow once. FWW did quite a good article on them a very long time ago - possibly a Mike Dunbar effort, can't remember. I presume when they talk about "manipulating the brace" they mean turn the top round in a circle to make the bell-shaped hole (thankyou! I was trying to think of a descriptive word at the time, but had a senior moment )

Originally Posted by Woodwould

I always glue Windsor type joints - not in the same fashion that I swab glue in mortice and tennon joints in other furniture forms, but I glue them with thin glue as much to swell the fibres as anything else. Wedges have been known to back out and actually fall out completely, so some glue on those doesn't do any harm either.

Agree with your sentiments wholeheartedly. I actually do put a smidgin of glue on most wedges, precisely for the reason you mention. One of the reasons I stopped using glue in certain places is because PVA glues (with which I had a pasisonate love affair many years ago), have a nasty tendency to grab when longish tight-fitting joints are pushed home. After a couple of disasters with sliding dovetails, I began to question just what the glue was for, & decided whatever it was, it wasn't adding much to structural integrity. I now either use a small amount of glue only at the end of a SD, or none at all if the rest of the structure, once fully assembled, will hold the part in place adequately without it. Makes disassembly that much easier, should it ever be necessary. I'm finally getting to the stage where I hope some of the things I make will a) last long enough & b) be considered worth repairing, if necessary. (That is, if there's anyone left on the planet still actually working wood in another 50 years time or so. )

I have finally returned to the 'true path' of using hide glue relatively recently. For a long time I was, I'm ashamed to admit, a victim of laziness & the propaganda that 'modern glues are so much better". Hide glue had become a dim memory as that foul smell at the back of the woodworking room in primary school days. About 10 years ago, I saw the light and began to rediscover its joys & sorrows. As I'm sure you well know, mixed right & handled well, it can actually 'lubricate' the assembling joint, yet grab once things cool off a bit. However, I'm still mastering all its little tricks & intricacies, & am a long way from feeling as confident with it as I'd like. At least so far, I have had way fewer failures with HG than with the various formulae of PVAs that have graced my bench over the years.

Cheers,

Thanks Woodwould and IW,
at this rate we may end up writing a book.

I still wonder whether the suitability of the wedge method is dependant upon the stability and hardness of the timber used? I am using Kauri Pine which is stable but soft.

As I expect the stools to have a hard life, I was careful to use suitable diameter tenons with maximum possible length. Should one leg break, I'd like to be able to replace it easily. I have shaped the legs with a shoulder which butts up against the underside of the seat. No doubt, the thought of using the wedge method with no glue appeals to me. One of the legs on my Grandpa's stool did break and was replaced. The hole did not appear tapered, but the tenon obviously was and there was no glue used.

Zelk

Originally Posted by IanW

WW - take a look at these:

http://www.thebestthings.com/newtools/clifton_bits.htm

I have a selection of spoon bits and one of those tapered reamers too. They're an odd beast to get the hang of, but are excellent at making clean entry and exit holes at the rakish angles involved with making Windsors.


PVA is to glue what the dowel is to fine furniture joints - they get the job done, but there's no substitute for animal glue and the mortise and tennon joint. I was suprised to read you strayed off the true path, but am relieved you regained your direction.

Originally Posted by zelk

I still wonder whether the suitability of the wedge method is dependant upon the stability and hardness of the timber used? I am using Kauri Pine which is stable but soft.

Possibly - but the Americans used very soft wood (white pine) for seats, which is supposedly why they used such thick chunks, necessitating the characteristic deep carving to avoid looking clunky. White pine is appreciably softer than good Kauri, IMO.

To glue or not to glue is your decision - the worst that can happen is that a wedge will back out or a leg come loose - both easily fixed. Amongst the bits made by my father that I noticed on the old home farm recently was a milking stool he cobbled up with a hatchet & brace & bit, from a rough chunk of not-too-hard hardwood with some Stringybark legs (I can dimly remember watching him do it & wondering at his accuracy with that axe!). Even the tenons were quickly shaped with the hatchet and fixed with nothing more than wedges. Probably took him less than an hour (though to me it seemed like a few minutes) & that stool is still as solid as a rock after being used morning & night for at least 40 years until they stopped keeping house cows 15 or so years ago.....

Originally Posted by Woodwould

I have a selection of spoon bits and one of those tapered reamers too. They're an odd beast to get the hang of, but are excellent at making clean entry and exit holes at the rakish angles involved with making Windsors.

Well WW, you'll have to teach youself to make that bell hole - then you can show us. As I said, I'd like to have a go at it someday, & make a whole chair with no glue at all, just for fun.

I think I'll wait for the Aussie dollar to regain some value before lashing out on a set of spoon bits, though.

You missed a set of used spoon bits and a taper bit on eBay within the past week Ian. I can't remember the figure, but they went for very little. I watched them because there was one size that I don't have, but then I thought it was ridiculous buying four or five bits just to score one.

Originally Posted by Woodwould

You missed a set of used spoon bits and a taper bit on eBay within the past week Ian. I can't remember the figure, but they went for very little. I watched them because there was one size that I don't have, but then I thought it was ridiculous buying four or five bits just to score one.

Dontcha just hate it when someone tells you you missed a bargain?

One of these days I'll come across a couple of useful sizes, when I actually have some cash in my pocket & in the right mood......