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  1. #1
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    Default Strong dowel joints?

    Hey everyone, I’m currently drawing up plans for a timber/glass display table. The glass I’ll be using for the top will be 3/8” thick (I was recommended this thickness for strength) and although I’ve never been involved with glass in my life, I’d assume it’s pretty heavy in a 900x650 panel.

    The table design only has 3 glass panels (top, front and side) while the remaining sides will be timber top to bottom. My preference for the leg design is to look like a mortise-tenon joint as them I’ll have 4 endgrain corners on the top.

    However the length of the timber I have won’t be long enough to make a tenon, and I figured my next best bet was to simply dowel it. But because of the weight of the glass on the front right corner I am concerned if timber dowels will be strong enough? Could I substitute them with stall bar the same diameter? Or is there a better method I could use? Thanks guys 😃

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  3. #2
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    Default

    a 900 x 650 glass panel 3/8" thick will weigh around 15 kg, which is not that much at all for a table frame to support.
    regards from Alberta, Canada

    ian

  4. #3
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    What size is your timer what is the table going to display e.g. weight, I would be including corner brackets

  5. #4
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    I can only imagine that this glass will not be a single point load.
    Many of my house windows are 60 x 90 sliders. Heavy but more awkward than anything.
    Lifting them out for washing is a PITA.
    Glued dowels ought to be OK.

  6. #5
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    Thanks guys. The timber will most likely be 50x50mm and yes the glass will be supported on all sides, I plan to have it recessed so it’s flush with the timber top and can’t just slide off the frame.
    In regards to regular dowel, would I be better off doing several I say an X pattern or just do two vertically? Thanks again everyone 😃 and thanks for the 15kg Ian, I was assuming much more haha.

  7. #6
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    2 vertical dowels should do; if you have them in an X pattern, the ones on the inside will cut into each other and be kinda useless anyway.

    Also, it's a good idea to have the glass toughened and any exposed edges ground so they're not sharp.

  8. #7
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    Hi Alexander

    I agree with Elan; glass should be toughened and edges polished.

    You might like to check with your glazier whether 3/8" is adequate for the size of your table panel. It must be able to withstand some ill-treatment!

    I have toughened glass sheleves in my kitchen cabinets - maximum size is 700 x 300 mm - and glazier recommended 8 mm toughened glass. When loaded with crockery you can see some deflection. Certainly wouldn't want anything less than 8 mm in my case.


    Cheers

    Graeme

  9. #8
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    I wouldn't use dowels on a glass table. That's a job for mortise and tenon. As your timber is too short to cut a tenon you could use slip tenons cut from a separate piece of timber. You then have the luxury of selecting a suitably strong piece of stick for the slip tenons.
    Dowels are for canary perches.

  10. #9
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    Quote Originally Posted by rustynail View Post
    I wouldn't use dowels on a glass table. That's a job for mortise and tenon....

    Dowels are for canary perches.
    Rubbish. For all practical purposes, dowels are just as strong as loose tenons.

  11. #10
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    Lots of really helpful advice guys 😃. I’ll definitely be in touch with a professional glazier before I start the build, but wot the frame being relatively chunky I should still be able to have it recessed into the top no problems.

  12. #11
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    Quote Originally Posted by elanjacobs View Post
    Rubbish. For all practical purposes, dowels are just as strong as loose tenons.
    Watch your mouth kid.

  13. #12
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    Quote Originally Posted by rustynail View Post
    I wouldn't use dowels on a glass table. That's a job for mortise and tenon. As your timber is too short to cut a tenon you could use slip tenons cut from a separate piece of timber. You then have the luxury of selecting a suitably strong piece of stick for the slip tenons.
    Dowels are for canary perches.
    Quote Originally Posted by elanjacobs View Post
    Rubbish. For all practical purposes, dowels are just as strong as loose tenons.
    Actually, I would say it depends on how well designed the table and where the joint is.

    If the rails are resting on top of the stiles and the dowels are just to stop lateral movement in the joint then dowels are fine.

    If the rail is butt-joined to the side of the stile - in which case the dowels could be considered load-bearing... Loose tenons are at least a bit stronger structurally used in that way.
    I may be weird, but I'm saving up to become eccentric.

    - Andy Mc

  14. #13
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    Quote Originally Posted by Skew ChiDAMN!! View Post
    If the rail is butt-joined to the side of the stile - in which case the dowels could be considered load-bearing... Loose tenons are at least a bit stronger structurally used in that way.
    Yep, butt joined 😂
    But only 4 of the 8 connections will require a dowel. As the table will be sitting against a wall corner the back two sides will be timber top to bottom, most likely rebate joined to the verticals, with the top horizontal rail attached to these firmly.
    The reason I opted for dowel was because they’re hidden. As I said before would using a metal rod in place of a weak timber dowel be more beneficial?

  15. #14
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    Quote Originally Posted by alexander95 View Post
    Yep, butt joined 😂
    But only 4 of the 8 connections will require a dowel. As the table will be sitting against a wall corner the back two sides will be timber top to bottom, most likely rebate joined to the verticals, with the top horizontal rail attached to these firmly.
    The reason I opted for dowel was because they’re hidden. As I said before would using a metal rod in place of a weak timber dowel be more beneficial?
    Metal? Not recommended. If you want to go that route I'd usggest dowels, then screw through from the other side, with the heads countersunk & plugged. They'll be hidden, right?

    Why? Metal expands/contracts with temp changes more than anything. Timber, change in humidity is a bigger factor, although temp does affect things. So the metal and timber would move at different rates, eventually causing the glue to fail.

    It's also one of the reasons why we try to make the loose tenons out of the same timber as the carcase they're going into. Using a different timber can have similar issues as different wood types have different movement rates. (Another argument against dowels in general. )
    I may be weird, but I'm saving up to become eccentric.

    - Andy Mc

  16. #15
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    Quote Originally Posted by elanjacobs View Post
    ..... For all practical purposes, dowels are just as strong as loose tenons.

    Aren't dowells just round loose tennons?

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