Author Topic: Chippendale side chair - knee blocks  (Read 8175 times)

Nobel

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Chippendale side chair - knee blocks
« on: December 02, 2014, 12:55:26 PM »
Hello everybody,

I had a quick question about attaching knee blocks on a chippendale side chair that I am in the process of attempting to build. I made my own plans based on pictures from Gene Landon, Israel Sack etc. and some drawings that I found in some other books (Lester Margon and Franklin Gottshall). I used Mary May's plaster cast for carving the ball and claw feet. All great fun.

Not having access to an original chair has not massively inconvenienced me, I think. However, I do have some questions. One relates to the knee blocks.

Since the grain on the knee blocks runs the same way as in the leg, the contact with the front and side rails would be end grain in the knee block. The question is therefore: how do you attach the knee blocks?

Do you just glue them to the legs, and not bother attaching them to the rails? Or is there hardware involved?

I'd much appreciate your insight on this.

Thanks for a great forum, by the way. It is a wealth of information for a hobbiest like me. I found the discussion on whether you use straight tenons or straight mortices for attaching the back legs of chairs to the side rails very interesting. I went with straight tenons and angled mortises.

Thank you,

Vincent Nobel
London, UK

daveknuth

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Re: Chippendale side chair - knee blocks
« Reply #1 on: December 02, 2014, 08:36:10 PM »
I am by no means an expert but on all the chairs I have made, the knee blocks are glued to the leg only and just butt up against the bottom of the front and side rails with no glue between the rails and the knee block.

Tom M

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Re: Chippendale side chair - knee blocks
« Reply #2 on: December 03, 2014, 08:09:59 AM »
Don't forget the rose-head nail!
Tom Meiller, SAPFM Member #684

Ken Johnson

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Re: Chippendale side chair - knee blocks
« Reply #3 on: December 03, 2014, 08:42:01 AM »
I am a little confused by your comment about end grain.

The leg and the knee block do have their grain in the same direction, vertical.  You should be able to glue long grain to long grain on the side of the leg and the knee block.  The end grain would go against the rail. You can glue it, but the main strength is the long grain.

Ken

Antiquity Period Designs, Ltd.

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Re: Chippendale side chair - knee blocks
« Reply #4 on: December 03, 2014, 08:53:10 AM »
I always apply glue (I use hot hide glue) both the long and end grain of the knee block. I then secure it with a rose-headed nail driven from the under side of the knee block into the leg.

Dennis Bork
Antiquity Period Designs, Ltd.
Professional period furniture maker since 1985.  Received a B.S. degree in physics then apprenticed and worked as a wood patternmaker for 12 years. Retired Dec. 2018.

Nobel

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Re: Chippendale side chair - knee blocks
« Reply #5 on: December 03, 2014, 09:39:53 AM »
Ken,

Indeed glueing to the leg is not a problem, but i was wondering whether it also needs to be attached to the rail. That is where the endgrain is, so I didn't think glue would be much help.

I'll whack in a nail for comfort.

Have any of you found such nails on original 18th century chairs?

Thank you,

Kirk Rush

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Re: Chippendale side chair - knee blocks
« Reply #6 on: December 04, 2014, 08:21:51 AM »
Yes, there are period pieces where the knee blocks have nails, too, but be sure to use a wrought head nail.

Kirk

Peter Storey Pentz

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Re: Chippendale side chair - knee blocks
« Reply #7 on: December 04, 2014, 07:04:27 PM »
Vincent,

There are many period chairs (and tables, also) that have knee blocks that are glued, with or without wrought nails.  I recommend using a wrought nail driven into the rail as a form of insurance against loss over time.  A lot of chairs have had one or more knee blocks replaced.  Also, sometimes the knee blocks are referred to as 'knee returns'.  PSP

Jeff L Headley

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Re: Chippendale side chair - knee blocks
« Reply #8 on: December 07, 2014, 06:25:24 PM »
OK! Just as a thought could the wrought nails have been added later? I would like to think our knee blocks would fit and stay on without nails. But maybe not. When reupholstering a slip seat remove the original fabric. A tight seat is a constant outward pressure which will cause stress on all joints. Remember angled mortises with straight tennons.

Nobel

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Re: Chippendale side chair - knee blocks
« Reply #9 on: December 08, 2014, 08:42:35 AM »
Thank you all for your input.

Indeed i have used straight tenons and angled mortises, both at the front and the back, even though all the drawings i have found in the different books i own show a straight mortise and angled tenon at the front. Some show the same at the back.

If i ever get this chair finished i'll post a picture, though i may comeback before that with another question.

Thank you

Vincent

Nobel

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Re: Chippendale side chair - knee blocks
« Reply #10 on: April 13, 2016, 10:38:49 AM »
I haven't had much time to work on this last year (none) but I am hoping to pick it up again. So here is another question:

What is the purpose of the shoe? Why can the back splat not be tenoned straight into the back rail? I have the shoe made so it is just curiosity I guess.

thank you

chrisstorb

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Re: Chippendale side chair - knee blocks
« Reply #11 on: April 13, 2016, 01:57:56 PM »
Certainly the splat can be tenoned directly into the seat rail. Chinese chairs that influenced the West's move to curved or "India" backs were made this way. A plinth or shoe however, raises the bottom of the splat off the seat and its upholstery. I've replaced many broken spats and have seen many splats replaced by others. We are very glad for the separate shoes that make this a much easier job than if the spat were tenoned directly to the seat rail.
Mid-18th century chairs that are upholstered over the seat rails have their splats tenoned to the rear seat rail and a removable shoe fit around the splat is nailed to the top of the rear seat rail to allow for the current and future textiles to be nailed to the frame.

Nobel

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Re: Chippendale side chair - knee blocks
« Reply #12 on: April 13, 2016, 05:28:57 PM »
That explains the shoes I found that only fit around the splat , rather than the splat fitting into it.

Thank you

Freddy Roman

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Re: Chippendale side chair - knee blocks
« Reply #13 on: April 13, 2016, 11:46:03 PM »
Great explanation Chris.
Freddy Roman
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