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Thread: CHAIR DESIGN 101
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21st May 2014, 03:32 PM #1
CHAIR DESIGN 101
At a recent meeting of Obsessive Compulsives Unanimous, where the roll was called and checked 7 times, I was heard to commit to making some chairs!
Not just ANY chairs but "something special to match the tables I made for my girls......
the secret project ... near the end of the journey
the problem (sorry, opportunity!) is that these tables were made to be used as a dining table, a breakfast bench, a desk and a hall table and so they are a non-standard height.
I referred to Uncle Google hoping to find formulae for chair dimensions and there are plenty for STANDARD tables ... but not these. So, I was on my own
I have the final design and design details all sorted out via my usual process of sleepless nights but I could only confirm the dimensions by making what I have called my ERGONOMIC PROTOTYPE (EP)
20140521_131508.jpg
The EP is wider and higher than the final design but I needed to make it like this so I could adjust it easily while taking it around to various daughters places and getting them to sit at the tables. So far i have confirmed seat height above ground, foot rail height and arm rest to seat dimension.
20140521_131454.jpg
but I needed to experiment with the shape of the back splat and so used this method of sliding blocks and dowels to get the profile right,
20140521_131613[1].jpg
but the final back splats will be vertical so I then tacked some vertical slats to the dowels and gave it repeated bum-in-seat comfort tests. I will refer to the standard formulae for width etc
20140521_135029.jpg
the final bum-in-seat-confirmed-shape is quite subtle with slight concavities above and below the maximum curve. I will now copy this profile and, yup you guessed it, back to Uncle Google to learn how to steam bend!
fletty
PS, sorry about the quality of the pics but, to be honest, I was too lazy to come up to the house and get my real camera?a rock is an obsolete tool ......... until you don’t have a hammer!
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21st May 2014, 04:00 PM #2GOLD MEMBER
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Glutton
You are not only OCDC but a glutton for punishment as well.
Don't know where you find the time, but look forward to the next instalment.
How many chairs was that again????
Greg
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21st May 2014, 05:48 PM #3
Excellent Fletty. I'm pulling up a chair...maybe a stool...to watch this one.
Greg I reckon 3 daughters x minimum 2 chairs each = a lot of work.Those were the droids I was looking for.
https://autoblastgates.com.au
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21st May 2014, 06:47 PM #4
Hope you have a few degrees on the seat.
The construction using the low arms instead of stretchers is problematic if dowels are used.
Easy to weaken the joints if the kids lean back too far.
Solved that myself by having 3 legs, one at the rear.
Mortice and tenon seem to survive ok but that could be due to the users.
H.Last edited by clear out; 21st May 2014 at 06:48 PM. Reason: Typo
Jimcracks for the rich and/or wealthy. (aka GKB '88)
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21st May 2014, 08:49 PM #5
Greg, hmmm, Tony got it right 3 x 2 = a bl**dy lot of work!
That beeeautiful Australian Red Cedar you milled for me PLUS the stunning crotch pieces I got from the auction last year give me enough timber, if not willpower, to make at least 8. The crotch pieces should give me the 8 shaped crest rails that I will need to get CNC'd with the family crest and name in Celtic font (many thanks to those who have volunteered to help!)
the GRAND PLAN is to make at least 6 and name each chair after one of my ancestors as per the flettrek blog of my travels through the islands in Northern Scotland.
Clear out, you raise some very good issues but I am still hoping to avoid stretchers on the side. The joins to the legs are rebated and pinned mortices and the joint at the front of the armrest will be a multiple finger joint.
I will probably make one from cr@ppy timber and test it to destruction before I commit my stash of red cedar? I would even consider a concealed metal splint like I saw on some Orcadian chairs after which these are styled
I made some good progress today. I get a little tired and jaded when I don't have a project on the go!
flettya rock is an obsolete tool ......... until you don’t have a hammer!
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21st May 2014, 11:09 PM #6
Hi,
This one might interest you if you have not already seen it.
Chair.jpg
RegardsHugh
Enough is enough, more than enough is too much.
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21st May 2014, 11:28 PM #7
wow Hugh, that's awesome......
l'm going to give up on the chairs and just make EP's!
My daughters are a bit out-there (they get it from their mother) and, having seen this l think my daughters wld prefer the quirkiness
flettya rock is an obsolete tool ......... until you don’t have a hammer!
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22nd May 2014, 12:05 AM #8Taking a break
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Interesting way to go about it.
For future reference, (seeing that you were looking for a formula/rule to go by) seat height is generally 240-280mm below table height and about 480mm above the floor or 450mm above an undercarriage for high chairs/stools.
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22nd May 2014, 11:36 AM #9Senior Member
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With respect, the first photo looks like the kind of chair you sit on after being asked what you would like as your final meal ...
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22nd May 2014, 12:14 PM #10New Member
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Interesting project!
I'm working on a dining chair project of my own at the mo, and after making a prototype set the seat height at 450mm. Those members of my family whose legs are shorter than other (AKA my wife) feels this is a bit high, but I am sticking manfully to my guns - any shorter seems to low and my own OCD aspect is chicken to deviate too far from the standard 480 - 500mm.
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22nd May 2014, 06:41 PM #11
Making chairs is like making seats for vehicles as far as dimensions go............measure floor to back of knee, back of knee to rear in seated position, then width at broadest point. I see you have already done this to a point. Like the racks of torture you've come up with so far but ya math is lousy cause where do you n H sit when visiting or the wee ones once out of high chairs Then there is safety issues quirky or not with design for wee ones.
Here you might find some interesting info on the Orkney Chair ............ is that the nah can't be way.
grab a coffee or Red
Edited to add - will have to be a case of bring own chairs for the girls maybe when all togetherLast edited by wheelinround; 22nd May 2014 at 06:48 PM. Reason: to add suggestion
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23rd May 2014, 12:40 PM #12Senior Member
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this looks interesting, I'll be watching this one for sure.
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24th May 2014, 06:17 PM #13
full steam ahead.....!
A full day in the shed ... woohooo..... oh, fix the vacuum cleaner first .... ahuh .... yes ... of course ..... the autumn leaves ....ahuh... yes, of course!
OK, I've googled steam bending, many times, and I'm aware I'm in danger of being a jig junkie ... spend all of the time making tools and jigs but making no woodwork. Time to stop looking and DO!
i started to make the plywood box
20140524_130219[2].jpg
which is double walled and held together with screws because the steam weakens the glue (thank you Google), the dowels hold the workpiece so that it is surrounded by the steam
20140524_141053.jpg
I gathered some odds and sods of pipe fittings
20140524_140605_1[2].jpg
fitted them to the sealed end
20140524_140802.jpg
and then assembled the whole menagerie, Wheelin's MIL's boiler, my MIL's hospital tray frame, chewing gum, duct tape, fencing wire.....
20140524_152116.jpg
and fired it up!
Apparently I need to achieve 90+ degrees and an hour per 25mm of thickness. Did I get there?
20140524_165100.jpg
wooohoooo.....!
flettya rock is an obsolete tool ......... until you don’t have a hammer!
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24th May 2014, 07:09 PM #14
Great job on the steamer Fletty. I'll have a couple of dim sims please.
Those were the droids I was looking for.
https://autoblastgates.com.au
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24th May 2014, 10:22 PM #15
Yum Char on the patio looking forward to it.
No fire under that Fletty no wonder you can't get it hot........ just don't use my wood stash
I'll bring the potato peels hear it makes great hooch