Does trestle table require top support? - Woodworking Talk - Woodworkers Forum
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post #1 of 22 Old 07-07-2019, 11:04 PM Thread Starter
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Does trestle table require top support?

I知 close to beginning sanding on an ash table I知 building based on my own design and a few online photos I used for inspiration (hence no plans to go off of).

See pictures below. I plan to attach the top to the bases using biscuit slots and some buttons I make with ash to allow wood movement.

My question is do you think I need a piece spanning between the top of the two bases? In other words, another piece running lengthwise that would be fastened to the underside of the top with more buttons.

My thinking is this would give the whole base structure extra rigidity if someone were to lean on the end of the table, thus reducing stress on the rest of the base痴 joints.

Would appreciate input on whether you致e built anything similar. I知 leaning towards this being overkill but am not opposed to spending some extra time on that piece. (I would however need to mill down some more rough saw ash which is time consuming with the deadline I have.)



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post #2 of 22 Old 07-08-2019, 06:03 AM
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What kind of joints do you have at the bottom of your end frames and at the ends of your long stretcher?
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post #3 of 22 Old 07-08-2019, 06:27 AM
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You need to provide dimensions.


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post #4 of 22 Old 07-08-2019, 07:56 AM Thread Starter
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Does trestle table require top support?

The lower stretcher is a cross lap joint. I知 thinking it will be a dry joint because I want to be able to assemble/disassemble the base in case we move. I値l maybe put a dowel through it that I can remove at a later point if necessary.

The top supports are attached to the legs with glue and (4) 2.5 wood screws and covered with 1/2 plugs.



The lower cross pieces are connected to the legs with 2.5 pocket hole screws and glue. I wanted that to be a through mortise joint but it痴 still a bit outside my skill level.

The top is 5/4 ash, 93.5 L x 43 W

Each of the legs is 3.25 x 3.25

Top of table will be 30 H

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post #5 of 22 Old 07-08-2019, 02:25 PM
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I don't know if this would help, but my father built a knockdown/trestle table about 25 years ago, the top is about 7ft long, 3ft wide, with the legs about 5ft apart, and made of 2x6" pine. No direct supports along the top, and is not permanently attached to the legs. It's still flat.
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post #6 of 22 Old 07-08-2019, 02:40 PM
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Depends on the rigidity of the joinery. If the bottom stretcher is solidly joined so there is no play, and the top is joined so there is no play, then it should be fine. Basically it comes down to the quality of the joinery. I've only built smaller trestle tables but they all had only one stretcher at either the top or bottom, none had 2, and they were all rock solid. But again, I've never built one that size and I think the top will play a significant role.
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post #7 of 22 Old 07-10-2019, 07:47 PM
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Quote:
Originally Posted by jbkennedy View Post
I知 close to beginning sanding on an ash table I知 building based on my own design and a few online photos I used for inspiration (hence no plans to go off of).
Good for you...sounds interesting. I love this style of table and build several traditional versions each year...

Quote:
Originally Posted by jbkennedy View Post
My question is do you think I need a piece spanning between the top of the two bases? In other words, another piece running lengthwise that would be fastened to the underside of the top with more buttons.
Usually there is (traditional about 40% to 50% of the time) on those with thin board tops.

I only use joinery...NO HARDWARE...Usually built traditional with only green or "unwaged" wood...and they are always "knock-down" as that is the nature of these tables, design and use context for the most part. They are the tables of the "common folk" and meant be be well used and last generations.

I would (very much) shy away from any "biscuit work" as these have not context in the table, are weak, and only meant for alignment when doing glue up and even then I find them worthless when compared to a toggle (aka free tenon.)

Quote:
Originally Posted by jbkennedy View Post
My thinking is this would give the whole base structure extra rigidity if someone were to lean on the end of the table, thus reducing stress on the rest of the base痴 joints.
Yes..and if you think you need it (your gutt!) THEN!!! you need it!!!

Feel free to send me an email...I'm on a timber frame project so do see them or this forum much accept on weekends or when I come into town...

Good Luck,

j
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post #8 of 22 Old 07-11-2019, 09:37 AM Thread Starter
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I知 leaning towards adding a top stretcher and two kickers, similar to this photo



The more I think about it, my cross lap joint is snug but not as tight as I wanted it. Given that I知 assembling during the summer and winter low humidity is around the corner, I worry about racking due to that joint loosening.

Maybe years down the road as my skills evolve I値l move towards all traditional joinery with no fasteners but for now, this will do job for a big Thanksgiving and Christmas spread!

I値l try to update the post with updates and final shots for reference.

Thanks everyone for your input.
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post #9 of 22 Old 07-11-2019, 10:06 AM
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I think you'll be ok, if you locate the trestles 18-20" in from each end, that's an unsupported span of about 58" max. You shouldn't have an issue with 5/4 ash.



BTW, the angled braces shown will not support the top from sagging.



If you were going that way, I'd be looking at angling the braces off the trestle bottom and angling up toward the middle). With or without a stretcher under the top running between the trestles.
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post #10 of 22 Old 07-11-2019, 11:03 AM
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sagging and the braces .......

Quote:
Originally Posted by jbkennedy View Post
I知 leaning towards adding a top stretcher and two kickers, similar to this photo



The more I think about it, my cross lap joint is snug but not as tight as I wanted it. Given that I知 assembling during the summer and winter low humidity is around the corner, I worry about racking due to that joint loosening.

Maybe years down the road as my skills evolve I値l move towards all traditional joinery with no fasteners but for now, this will do job for a big Thanksgiving and Christmas spread!

I値l try to update the post with updates and final shots for reference.

Thanks everyone for your input.
Quote:
Originally Posted by DrRobert View Post
I think you'll be ok, if you locate the trestles 18-20" in from each end, that's an unsupported span of about 58" max. You shouldn't have an issue with 5/4 ash.



BTW, the angled braces shown will not support the top from sagging.




If you were going that way, I'd be looking at angling the braces off the trestle bottom and angling up toward the middle). With or without a stretcher under the top running between the trestles.

Exactly! Just reverse the braces and angle them up towards the top.
A center spine will help prevent racking if the braces are connected to it. However, that may not be necessary, because the center plank of the top used as the anchor point, will prevent any racking also.


The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #11 of 22 Old 07-11-2019, 11:15 AM Thread Starter
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Quote:
Originally Posted by DrRobert View Post
I think you'll be ok, if you locate the trestles 18-20" in from each end, that's an unsupported span of about 58" max. You shouldn't have an issue with 5/4 ash.



BTW, the angled braces shown will not support the top from sagging.



If you were going that way, I'd be looking at angling the braces off the trestle bottom and angling up toward the middle). With or without a stretcher under the top running between the trestles.


Yes I知 not too concerned about sagging. The top is STOUT. But since I知 looking at going this route and the aesthetic won稚 change much by reversing the angled braces and I would gain some resistance from sagging, it might make more sense to do that.

I壇 never really thought about all the leverage involved in a table before building one of this size!
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post #12 of 22 Old 07-17-2019, 02:57 PM Thread Starter
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Quick update for anyone following along or considering this for your own creation -

As was suggested above, I went with my gut and added a top stretcher and two angled kickers.

The top stretcher is a lap joint which will be attached to the base with 3 screws.

With two lap joints and the angled kickers there is basically zero play in the base. And I can still take the entire table apart into four pieces if we temporarily need space or move some day.

I知 sure with proper joinery someone could have made this setup rigid without a top stretcher or kickers.

Tonight I値l be applying Rubio Monocoat finish. Tomorrow night I値l be attaching the top to the bases with z clips and possibly screws in the middle board.








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post #13 of 22 Old 07-17-2019, 06:03 PM
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Why rectangles "rack" .....

When you added the angled braces, that stopped the racking. The reason is a triangle will not collapse when pressure is put on the sides or a corner, unlike a rectangle, which will. Put a diagonal brace inside a rectangle and it will not collapse. This forms 2 internal triangles and that why bridge or construction trusses are all made with triangles.


No amount of joinery will replace the angled braces .... unless you use welded steel.
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The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 07-17-2019 at 06:05 PM.
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post #14 of 22 Old 07-17-2019, 09:54 PM Thread Starter
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Quote:
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When you added the angled braces, that stopped the racking. The reason is a triangle will not collapse when pressure is put on the sides or a corner, unlike a rectangle, which will. Put a diagonal brace inside a rectangle and it will not collapse. This forms 2 internal triangles and that why bridge or construction trusses are all made with triangles.


No amount of joinery will replace the angled braces .... unless you use welded steel.


Exactly! They made a huge difference.
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post #15 of 22 Old 07-18-2019, 08:17 AM
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I have never built a table without stretchers or otherwise supports.
I really like the table design in post No.8.
So this leads to the following question:
I know of calculators for joists and other house construction beams. Are there any charts or calculators for span lengths used in furniture construction?

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post #16 of 22 Old 07-18-2019, 10:07 PM Thread Starter
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I have never built a table without stretchers or otherwise supports.

I really like the table design in post No.8.

So this leads to the following question:

I know of calculators for joists and other house construction beams. Are there any charts or calculators for span lengths used in furniture construction?


I致e come across something called the Sagulator specifically for shelves but could probably be applied to tabletops. It calculates the sag based on size, span and wood species.
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post #17 of 22 Old 07-19-2019, 07:28 AM
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..............Sagulator specifically for shelves but could probably be applied to tabletops. It calculates the sag based on size, span and wood species.
I forgot all about "sagulator". Not having done any significant woodworking in several years, one tends to forget a lot, now couple that with age and, well, you get my point.
Anyway, I tried it using a 6/4 table top (using 1.5), 60" between spans, 30" front to back, southern red oak approximating 20 load in center only and whatever other items were on there and I came up with and acceptable limits or something like that. This was just a hypothetical shelf (table top) just to test out sagulator. If I were to actually build a table top with a 60" span, I would probably use 8/4 if for no other reason, just for looks.

Anyway, thanks again.

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post #18 of 22 Old 07-19-2019, 01:43 PM Thread Starter
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Alas the table is done (minus attachment of z-clips). Quite pleased with how it came out and I especially love the buttery smooth satin finish of Rubio monocoat which allowed me to maintain the light color of the wood.

One thing I知 not wild about is how much darker some pieces of wood are than others, specifically the legs. Not a huge deal but something I will like give more consideration for future projects.



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post #19 of 22 Old 07-20-2019, 10:13 PM
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Great JOb
Looks beautiful and the legs are what they are. Take it from me, I'm a leg man.

Walk through larger furniture stores and you will notice that even manufactured tables dont always have matching legs nor do tables and counter tops always have matching boards. That is what separates the natural from the artificial.

Be proud of your work.
And whatever you do, don't go around pointing out the legs to other folks. Let them see them on their own and they will comment.

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post #20 of 22 Old 07-21-2019, 01:32 AM
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Very nice work!

Quote:
Originally Posted by jbkennedy View Post
Quick update for anyone following along or considering this for your own creation -

As was suggested above, I went with my gut and added a top stretcher and two angled kickers.

The top stretcher is a lap joint which will be attached to the base with 3 screws.

With two lap joints and the angled kickers there is basically zero play in the base. And I can still take the entire table apart into four pieces if we temporarily need space or move some day.

I知 sure with proper joinery someone could have made this setup rigid without a top stretcher or kickers.

Tonight I値l be applying Rubio Monocoat finish. Tomorrow night I値l be attaching the top to the bases with z clips and possibly screws in the middle board.









Besides looking just awesome, it will come apart for moving! I don't know if there is a way to attach the top without fasteners, but that would be very cool if there was. I have found 2 sided carpet tape to be very "aggressive" so just a couple of strips would work. You just don't want a sudden bump to shift it on the base, especially with a table full of food and dishes.
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The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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