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Thread: Question for you engineer types

  1. #16
    Join Date
    May 2015
    Location
    NW Indiana
    Posts
    552
    Hey Mark - similar to what I'm thinking about. Bought the wood for it but it's getting pushed behind the dining chairs the love of my life has ordered. And it looks like you are deep in a conversation with someone in that pic.
    If you don't stand for something, you'll fall for anything.

  2. #17
    Join Date
    Jul 2007
    Location
    Inkerman, Ontario, Canada
    Posts
    440
    Priorities.

    I had a lot of fun messing with chair designs exploring structure, most were just rough prototypes of ideas i had, i would love to get back into doing some again, concentrating more on the style aspect.

    In that photo i was speaking to the customer that i was building the dining table for, there were also ten chairs that went with it. I have to be conscious of posting old photos with other people in these days, so i generally crop them out.

    Go crazy have some fun with your design, you will be amazed at how strong wood can be.

    Quote Originally Posted by Bill Carey View Post
    Hey Mark - similar to what I'm thinking about. Bought the wood for it but it's getting pushed behind the dining chairs the love of my life has ordered. And it looks like you are deep in a conversation with someone in that pic.

  3. #18
    Join Date
    Dec 2010
    Location
    WNY
    Posts
    6,051
    I'm an engineer and my opinion is B will be stronger because the grain of the tenon will be optimal when running horizontally. In contrast, no matter which way you orient the grain in A you will have less than optimal strength somewhere.

    John

  4. #19
    Join Date
    Jul 2007
    Location
    Inkerman, Ontario, Canada
    Posts
    440
    part6.jpg
    While B may be the more obvious choice, on face value, but the OP didn't give us all the variables, and it is therefore difficult to give an accurate answer, i like to get as much info as possible about the application before i would write some way off or recommend another.

    Grain direction makes a difference and I don't see that you will have less than optimal strength in A. I don't see much if any strength difference in doing the joint like A or B, depending on the application.

    There are many ways that you can do a joint, mortise and tenon, with side shoulders and top and bottom shoulders, without top and bottom with one or the other, with inset or angled shoulders, you can also do bridle joints or combination joints, depends on the application, stock size, length, species grain direction and load. Lots of variables and joints can be designed around those variables to best suit the application.

    Quote Originally Posted by John TenEyck View Post
    I'm an engineer and my opinion is B will be stronger because the grain of the tenon will be optimal when running horizontally. In contrast, no matter which way you orient the grain in A you will have less than optimal strength somewhere.

    John

  5. #20
    Bill Carrey,

    I hope I'm understanding the situation.

    When the situation is drawn to scale and given the 20" projection supporting an unknown weight near the outermost point, I'd suggest:

    Shelf Bracket_20 IN_Wood_8.2.19.JPG.jpg

    1. If the weight is on the outside end the outer edge should be thickened.

    2. If it's convenient, for maximum bearing, the diagonal bracket bottom should be as close to 45 Deg as possible.

    3. Supporting the shelf at the outside means the tendency is for the bracket to pull away at the top. I think that 3/4" diam, hardwood dowels will resist this tension better- and be much easier to make than the angled through tenon. Anyway I think the tenon will remove too much material from the 2" X 2" vertical support and not leave enough on the sides. The lowest dowel is shown shortened, but could be drilled through and cut off flush. That would increase the gluing surface area. If appearance is a factor, it could project a bit and be cut vertically as a visible peg end.

    Alan
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