Thread: Prototype Dining Chairs

Hi John

Someone much smarter than me once said that the engineering of a simple dining chair was much more complex than a Boeing 747. Maybe that is why I like the design phase of design and make so much.

I have never made a chair like you are proposing, but ... The overall shape is reminescent of the profiles of Regency balloon back dining and hall chairs of 200 years ago - they always seemed to put a lot of effort into ensuring that the grain direction flowed around the balloon; given the stresses when a chair is abused (eg rocked) I am a little concerned by the vertical grain in your chair back.

Balloon Back Chairs.jpgRegency Balloon Back Chairs c.1800

It might be worth your visiting a few antique shops and also googling to see if you can get any insights from these antiques.

Secondly, prototyping in rosewood must be a first. I thought that was why plantation timbers were invented - radiata, nitens, meranti, whatever.

Thirdly, a few random thoughts:

• If you round over the edges more then you will lighten the visual footprint, and increase the elegance,
• How are you going to attach the back to the base? Really high stresses are involved,
• Have you tried finishing and polishing an offcut of the rosewood to see what the end result may look like?
• Rear legs on chairs are usually splayed backwards a little to discourage people from rocking.

I shall be watching you progress with great interest. Please feel free to PM me if there is anything that you would like to discuss privately (or if I annoy you!)

Originally Posted by GraemeCook

Hi John

Someone much smarter than me once said that the engineering of a simple dining chair was much more complex than a Boeing 747. Maybe that is why I like the design phase of design and make so much.

I have never made a chair like you are proposing, but ... The overall shape is reminescent of the profiles of Regency balloon back dining and hall chairs of 200 years ago - they always seemed to put a lot of effort into ensuring that the grain direction flowed around the balloon; given the stresses when a chair is abused (eg rocked) I am a little concerned by the vertical grain in your chair back.

Thanks for all the input, Graeme.

I have made a total of five chairs, all for kids, and all like those in the pic below.

Suite.jpg

The reason there have not been any other chairs was wonderfully explained by Graeme.

Is the seat to be square or tapered toward the back? Will the seat be flat or leaning back at a slight angle? It goes on. The design of a chair can be very complex, and if one variable is changed, chances are so are several others. Chairs can be a bloody nightmare. That's why I have limited myself to kids chairs so far.

First let's address the vertical grain on the back of the chair. Not sure if being two one inch boards glued together helps or not, but strength was a minor concern for me until I took it out of the clamps after glue-up. It's very strong and now causes me no concern whatsoever. Answering this strength question was part of the reason for making the prototype.

I am familiar with NG Rosewood and with finishing it. I bought a small pack at a good price, and am working my way through it. The last piece made with this timber was a tall chest of drawers made for my nephew.

I struggled with the design for a while ... that struggle continues. Wanted to use cabriole legs with aprons shaped to match the legs. This made any shape other than square problematic. After a bit of messing around I asked myself what is the most celebrated chair ever made? My answer was "the Hans Wegner round chair". It has a square rather than tapered seat, and usually there is little to no tilt to the rear for the seat. The back legs are not splayed to the rear by much, if at all. Most joints look fragile, and are certainly not substantial. It breaks nearly all the "rules" for chairs we read about. And yet, if a woodie refers to "the chair", most know the Wegner round chair is being spoken about. It is both beautiful and iconic.

So I am trying to not be bound by rules and conventions. I want a pretty chair, preferably with a low back. It also needs to be comfortable.

Joining the back to the chair is planned to be done with two 8 mm tenons on either side (and probably, epoxy glue). The plan is to make a prototype and to severely test it. Given that all the surfaces of the tenon flats will be glued to long grain, I am optimistic.

At this stage I've not even finalised the design. All I'm doing is prototyping bits and pieces I am reasonably sure will form part of the final design.

Does anyone have any bright ideas about rounding over the edges of the centre piece for the back?

Time to make a complete chair ... still a prototype and still subject to change.

First a template for the cabriole legs was made. Found an existing template that was close and extended it by 15 mm.

Template.jpg

Then the timber was dressed, cut to length and marked up, followed by cutting on the band saw. Then the legs were cleaned up on the linisher, but still squared, and examined to check that all four were pretty much the same.

Square.jpg

Finally the legs were rounded off, first on the linisher, then on the spindle sander. Finally they are hand sanded to get them smooth and straight.

Rounded.jpg

Next the aprons will be prepared ... when I get around to them.

Please do not suffer under the misapprehension that cabriole legs are difficult to make. I made that mistake ... until I decided to make a single leg ... and surprised myself with how quickly and easily the first leg was made. Timewise I allow half a day to make four cabriole legs big enough for a sideboard or similar.

The aprons were marked out with the leg curves on each end. Then they were passed over the table saw with an angled blade a couple of times to trim most of the waste off before assembly.

Aprons were joined to legs with two 8 mm X 50 mm tenons in each joint. Aprons rough sanded by "rolling" them on the linisher and then finished with a ROS. Everything will be hand sanded before the backs are attached.

IMG20220316092945.jpg

But they did not look right. The centres of the aprons were too low, resulting in too much "movement" in the bottom edge. 10 mm was removed from the lower part of each apron and the result is much better. Might even take another 5mm off.

Sides of the back have been cooked and are clamped onto the jigs that put some twist in them. They were left in the clamps overnight.

Back assembled and sitting on the base. Got the curve for the back right this time. Top yet to be rounded over and 5 degree slope not yet cut into bottom of base.

IMG20220317091434.jpg

This time the grain direction is different in the top section of the back. Don't like it much, but there it is. Also a piece was added that joins the bottoms of the sides together. Most of this will disappear behind the cushion, and it adds strength.

Originally Posted by John Samuel

Joining the back to the chair is planned to be done with two 8 mm tenons on either side (and probably, epoxy glue). The plan is to make a prototype and to severely test it. Given that all the surfaces of the tenon flats will be glued to long grain, I am optimistic.

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Does anyone have any bright ideas about rounding over the edges of the centre piece for the back?

I would use hide glue over epoxy. It will allow for future repairs to the chair without destructive disassembly. Liquid hide glue is fine.

Antique sets of chairs that have always been together often have variations within a set because they were made with hand tools. These differences might not be immediately obvious unless you look closely. Rounding over would have done using a rasp and/or spokeshave by previous generations of chair makers. They are still good tools for the job. Don't stress if there are subtle differences.

Originally Posted by markharrison

I would use hide glue over epoxy. It will allow for future repairs to the chair without destructive disassembly. Liquid hide glue is fine.

Antique sets of chairs that have always been together often have variations within a set because they were made with hand tools. These differences might not be immediately obvious unless you look closely. Rounding over would have done using a rasp and/or spokeshave by previous generations of chair makers. They are still good tools for the job. Don't stress if there are subtle differences.

Oops ... too late, Mark.

The epoxy is at the plastic stage as I type. I doubt it's the end of the world, but thanks anyway. I decided to avoid cutting mortices at odd angles with the Domino. The back is being held on with clamps 'till the glue sets, and it is a lovely fit. Once the epoxy has set (tomorrow) I'll drill 7-10 holes for dowels from underneath using my Kreg pocket hole jig and a wedge made up to get the dowells in the right position/angle. I'll put 2-3 dowels into each upright of the back, and a few into the member joining the sides at the bottom. I like this method of dowelling because the dowells are a perfect fit, given that the joint is already made. I do a similar thing with drawers.

I managed to get the edges rounded over and sanded smooth. As you suggested, the job is not absolutely perfect, but I doubt anybody other than thee and me would notice. I'll get another chance to hand sand everything before applying lacquer.

At any rate I am very happy with the chair for now, although all bets are off until it gets the bum test. I'll make a drop-in frame that sits on and into the aprons and upholster it with elastic webbing and foam.

This chair is a prototype. If it does not come up to scratch for any reason I'll amend the design and make another until I am happy with the job. I like the cabriole legs and the effect gained when the aprons are shaped to match the legs. I'm thinking of making another (one day) where the design is more like the balloon back chair Graeme posted earlier.

If I do that, what would you blokes recommend; steam bending the back legs or cutting the shape out of a larger section of timber?

Originally Posted by John Samuel

This chair is a prototype. If it does not come up to scratch for any reason I'll amend the design and make another until I am happy with the job. I like the cabriole legs and the effect gained when the aprons are shaped to match the legs. I'm thinking of making another (one day) where the design is more like the balloon back chair Graeme posted earlier.

If I do that, what would you blokes recommend; steam bending the back legs or cutting the shape out of a larger section of timber?

I have not made a whole chair, but I have restored balloon back chairs including creating new balloon back tops.

In theory; it should be possible to steam bend backs and rear legs. If you have the tools and experience or just want to give it a go, I can see no reason to not try it.

I just cut the tops to shape from larger blocks with a bandsaw then refined the shape with spokeshaves and rasps. I just eyeballed it. I'm pretty happy with the outcome and I am my own harshest critic.

When I compare the results to the other chairs in my circa 1880 Australian red cedar set, I can see no difference in the grain pattern to what I built. This leads me to believe that the original craftsmen used the same technique.

Thanks, Mark.

I'm inclined the same way.

The chair itself is finished, including lacquer.

Lacquer on.jpg

Sitting on top of the seat can be seen a frame that drops into place between the aprons as well as sitting on top of the aprons. No fasteners are needed to hold it in place. The upholstery supplies to finish it have been ordered, so now we wait for it to turn up.

Finished.

Elastic webbing stapled to the removable frame. Felt cover over that, followed by foam cushion, the dacron and finally the fabric.

IMG20220328135100.jpg

She who must be obeyed is most impressed with the soft, comfy seat. However, she thinks we need a redesign to give her lower back more support.

I think the 50 mm foam is too thick and would drop it back to 25-35 mm. The elastic webbing means a thinner foam would not be a comfort issue.

Next prototype ... perhaps ...