Page 1 of 5 12345 LastLast
Results 1 to 10 of 47

Thread: Tight Wire Chairs

  1. #1
    Join Date
    Oct 2006
    Location
    Tokyo Japan
    Posts
    15,807

    Tight Wire Chairs

    OK here we go, I've started the build of two tight wire chairs.



    The chair makes it's appearance at about the 1:31 mark.



    A picture of the chair in use.



    here is a line drawing of it.

    From the source, here is what they have to say about the wear and tear of the chairs.

    In the show, after the chair is dropped from the Highwire, it bounces in the net; this does not hurt the chair.
    After the net is released, depending on how fast is comes down, it hits the stage at different angles every night.
    The damage is inconsistent and unpredictable so we want the whole chair to be built with strength in mind.
    The drop to the stage is about 2 meters, or just over 6 feet, twice a day, so building for strength is paramount.

    The design is all fairly straightforward, with the exception of the rear leg.

    To make that rear leg in one piece I think is a mistake, it will just snap. It splays out to the side and out to the back.

    I have the idea of making it out of several thin pieces of wood, and bending the rearward splay into the lamination, while leaving the width of the lamination wide enough to cut the sideways splay on the bandsaw, if that makes sense.

    I'd love to hear some ideas if you have them

    The front leg is most likely to fail, look at this picture....



    The close up is of the side of the front leg.



    How to make these corners stronger. I think that they are just simple Mortise and tenon, but know one knows for sure, as the paint is rather thick, but I've been toying with the idea of doing a sliding dovetail to make the joint stronger, but maybe that is not a good idea, and I should just go with mortise and tenon and then pin them as I did with the Chinese chairs....?

    The wood is beech, it is strong and works well, and as it is paint grade the simple grain does not matter.

    The chairs are reinforced with metal brackets and such, which I'll also be making, more on that later.

    Not nearly the volume of the Chinese Chairs, but they are certainly more complex.

    I'd certainly like you input on these.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  2. #2
    Join Date
    Dec 2006
    Location
    Yorktown, Virginia
    Posts
    5,022
    Very cool, but I hope you have more than a hand shake that says you are not liable for any chair failures.

  3. #3
    Join Date
    Jun 2008
    Location
    GTA Ontario Canada
    Posts
    12,264
    I think you have the absolute right idea with bent lamination's i am always reminded when it comes to something like you asking about of the Danish furniture industry. Chairs like this



    When you consider they take the full weight of a person on that single front leg.


    Perhaps several bent laminations assembled together.

    And for the wood i would look at using european beech as they do in plane bodys etc. Its a nice dense wood and stable and straight grain which should not present too many issues in laminating.



    This is the grain of the beech type I am thinking off. Its tough stuff have a small slab in my shop. Type of stuff used in those coffin planes made by Mathieson and used for many other woodworking tools through the ages. Stands up well to wear and tear and holds its shape.

    Looking forward to watching this adventure.

    Whats the news on the previous batch of chairs ? Have they been used and tested yet ? Customer delighted ......I take that for granted by the effort you went to.

    Best of luck.
    cheers

  4. #4
    Join Date
    Oct 2006
    Location
    Tokyo Japan
    Posts
    15,807
    Quote Originally Posted by Ted Calver View Post
    Very cool, but I hope you have more than a hand shake that says you are not liable for any chair failures.
    Yes that is spelled out in the contracts Ted
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  5. #5
    Join Date
    Oct 2006
    Location
    Tokyo Japan
    Posts
    15,807
    Quote Originally Posted by Rob Keeble View Post
    I think you have the absolute right idea with bent lamination's i am always reminded when it comes to something like you asking about of the Danish furniture industry. Chairs like this



    When you consider they take the full weight of a person on that single front leg.


    Perhaps several bent laminations assembled together.

    And for the wood i would look at using european beech as they do in plane bodys etc. Its a nice dense wood and stable and straight grain which should not present too many issues in laminating.



    This is the grain of the beech type I am thinking off. Its tough stuff have a small slab in my shop. Type of stuff used in those coffin planes made by Mathieson and used for many other woodworking tools through the ages. Stands up well to wear and tear and holds its shape.

    Looking forward to watching this adventure.

    Whats the news on the previous batch of chairs ? Have they been used and tested yet ? Customer delighted ......I take that for granted by the effort you went to.

    Best of luck.
    Yes Rob, European Beech is the wood to be used. I think making a basic caul that will allow me to glue up a bent lamination for the backwards splay, and then bandsawing out the sideways splay will work well.

    The other chairs have arrived and so far everyone is pleased, they now have to be fit together into a stack, then finished and then fit together again. I've been promised pictures along the way.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  6. #6
    Join Date
    May 2007
    Location
    Thomasville, GA
    Posts
    6,000
    The line drawing shows metal reinforcements at the bottom of the legs and across the stretchers. A 3-way metal brace at the top of the legs would strengthen whatever joint you use for the wood.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  7. #7
    Join Date
    Jul 2011
    Location
    The Gorge Area, Oregon
    Posts
    4,701
    Well this will be interesting, some engineering challenges for sure

    I think your bent lamination theory is spot on. I'm not sure how bad the current design is but your improvement would certainly be better (under the "better to over engineer theory).

    The vertical stress crack you're showing on the front leg is certainly interesting. I think that that joint is to sharp to do a reasonable bent lam there... I suspect a dovetail won't help much because of the failure mode (the rail isn't pulling out the leg is failing). I almost wonder if a metal strap running from the front of the leg up over the top onto the stretcher or maybe a tension rod run through the stretcher providing tension front<->back might be a solution...

  8. #8
    Join Date
    Oct 2006
    Location
    Tokyo Japan
    Posts
    15,807
    Thanks guys.

    Ryan, how about something like this....?



    Obviously not to scale etc, but you get the idea, the aprons are still mortise and tenoned into the top of the leg, and then a thin, 3mm thick piece of steel is let into the top of the leg and the tops of each apron for each front leg, screwed and epoxied into place it should not move. Of course the underside of each apron would still get the brackets like on the old chair.
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  9. #9
    Join Date
    Jul 2011
    Location
    The Gorge Area, Oregon
    Posts
    4,701
    Quote Originally Posted by Stuart Ablett View Post
    Ryan, how about something like this....?
    Something kind of like that yeah... I'm not a structural engineer and am struggling more than a bit to imagine the vectors on all the forces involved so take what I'm saying here for what that's worth (and I'm thinking out loud a wee bit here so play along and correct where it seems way off base, please ).

    What I think is happening on the front leg is the bottom corner of the leg[1] is impacting causing the chair to flex diagonally (direction indicated by arrows[2]) causing the joint at [3] to be flexed out at the end (3 isn't quite right but I think conveys the rough theory) ([1,2,3] indicate my rough scribbles in the picture).

    Click image for larger version. 

Name:	tightwire_chair_forces.jpg 
Views:	15 
Size:	34.5 KB 
ID:	92578

    Obviously the same thing should be happening to the rear leg. What I believe is saving it in that case is that there is sufficient material above the joint to prevent it from splitting (the forces ought to be about the same and we see the same indication of impact points on the corners of the legs).

    I think the crack there implies that the whole chair is flexing somewhat (you might be able to see evidence of this in the stretchers if there are compression points on the ends of them, maybe not though... depending on where it flexed). Its possible that the bottom rung is actually flexing up in the middle a bit I think that means that you might also be able to mitigate the issue somewhat by proper construction of those and maybe its all a moot point.

    I was thinking if there was tension all the way to the front of the leg it would help mitigate the flex as well, but I'm not sure on the best way to do that. Your idea certainly seems like a reasonable one to try.

  10. #10
    Join Date
    Oct 2006
    Location
    Tokyo Japan
    Posts
    15,807
    Basically I agree with your assessment Ryan.

    I don't know if I'll do the let in bracket, but I am now thinking of making the front leg out of a laminated piece too, and even including fiberglass cloth in between each piece of laminated wood.

    Should never split if I do that.
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

Similar Threads

  1. Just Under The Wire
    By Charles Hans in forum General Woodworking Q&A
    Replies: 11
    Last Post: 11-22-2014, 03:09 AM
  2. And you think your garage is tight...
    By Chuck Ellis in forum Off Topic Discussion
    Replies: 5
    Last Post: 09-15-2010, 07:31 AM
  3. Tight is Good !
    By Dave Hawksford in forum Finishing School
    Replies: 1
    Last Post: 03-24-2010, 03:46 PM
  4. Tight fisted turning
    By Pete MoncrieffJury in forum Lathe Project Showcase
    Replies: 4
    Last Post: 02-19-2009, 01:26 AM
  5. That Drill Chuck is on Tight!
    By glenn bradley in forum General Woodworking Q&A
    Replies: 19
    Last Post: 06-24-2008, 05:37 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •