Knockdown table top?

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Forum topic by leftcoaster posted 04-17-2019 12:16 PM 637 views 0 times favorited 17 replies Add to Favorites Watch
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390 posts in 1960 days

04-17-2019 12:16 PM

I’m making a knockdown dining table for overflow seating on holidays. As it will be covered with a tablecloth, I’m cheaping out and using some tongue and groove cedar siding a buddy gave me for the top. The table may get used outside, so this is a plus.

I don’t want to glue up the entire tabletop as it will be about the size of a sheet of plywood – awkward to store. I have glued up two halves, which is more manageable.

What’s a good way to join the two halves temporarily, for use on the table? There is a tongue and groove, but that’s not secure without glue. Assume I don’t want to screw and unscrew into the panel bottom repeatedly.

Maybe two blocks glued underneath with matching through mortises? I could pass a loose tenon through and hold it with a wedge?

17 replies so far

View mahdee's profile


4291 posts in 2851 days

#1 posted 04-17-2019 12:29 PM

You can screw two blocks-one at the end of each panel and cut a U shape that fits snug over the two blocks. If you taper the edges of the blocks inwards and the U out, then there is no chance of it falling


View Blindhog's profile


185 posts in 2132 days

#2 posted 04-17-2019 12:37 PM

If you have a festool domino, the connectors work well…..............


-- Don't let perfection get in the way of plenty good enough

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John Smith

2925 posts in 1246 days

#3 posted 04-17-2019 12:37 PM

if only used during the holidays for overflow dining,
and mostly used outside, why not just throw a piece of
3/4” plywood over a couple of sawhorses.
then after the get-together, all goes back to the shop to be
used in whatever you need it for.
(just seeing too much effort being put into a project that will not be seen
as it will be covered with a tablecloth and only be used a few times a year).



-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

View Delete's profile


439 posts in 1455 days

#4 posted 04-17-2019 12:57 PM

The easiest way is to do same as you would do for any solid top that requires that you allow for wood movement. Make up 8 tabs like in the sketch. They screw into the underside of the table top four to each section and register into slots cut into the apron. The top is two sections so I assume the base will have an apron. Loosen the screws 1/2 turn, pull the tabs back, and remove tops. Install top, slide tabs into slots tighten screw half turn, done. You don’t need to clamp the two sections together, you already have T&G to join the to sections flat, you just need the means to join the two sections firmly to the base.

View Nubsnstubs's profile


1774 posts in 2813 days

#5 posted 04-17-2019 01:41 PM

View leftcoaster's profile


390 posts in 1960 days

#6 posted 04-17-2019 02:26 PM

So many good ideas here! Really appreciate the creativity of the group. Couple of things:

I’m a hobbyist, so I treat projects like this as skill building exercises. Aside from the milling, I made the trestle base by hand and was mostly successful at getting a friction fit. So, metal fasteners aren’t my first choice, useful as all of those seem to be.

As it’s a trestle, I can’t use buttons because there’s no apron to screw into.

I like Mahdee’s idea a lot—sounds like a faceplate for a double light socket—the blocks are sort of tenon like and if I made a rectangle rather than a U, it would have two through mortises to capture each block.

Another variant of this idea would be to mortise the blocks and orient the mortises so they run parallel to the top, then secure them with bypass wedges. Mahdee’s idea is appealing because sliding on the retaining “plate” wouldn’t stress the attachments of the block as much as tapping in the wedges might.

View Delete's profile


439 posts in 1455 days

#7 posted 04-17-2019 03:03 PM

Knowing it’s a trestle style changes everything. Heres an idea:

Since your top is two sections cut the three center uprights shorter and the two outside uprights longer to mortise into the two top sections. To assemble, join your two T&G’ed sections, drop in place over the four tenons, install wedges, done. The whole assembly is knock-down.

Here’s the link to my post.

View jonah's profile


2136 posts in 4382 days

#8 posted 04-17-2019 03:14 PM

I’d use one of these, rather than making something. If you’re only using it twice a year, why spend the time to overengineer something?

View leftcoaster's profile


390 posts in 1960 days

#9 posted 04-17-2019 03:33 PM

Carlos that is an awesome idea.

Jonah, it’s a hobby and so not entirely a rational decision. And, yes, it’s fun for friends to see the fruits of our labors, no?

Also, my cost of materials is a third of that table, which is two feet short and would have to be stored at full width. Definitely a good option for most people!

View smitdog's profile


470 posts in 3188 days

#10 posted 04-17-2019 03:48 PM

Is there anything underneath to support the weight of the top? If not your joint is going to have to bear all the weight. What if somebody sits on the table? You don’t want your joint to break and someone come tumbling down. I’d just screw some heavy runners to the bottom of it across the joint to spread that load out. You could dado the joint or use biscuits to keep the tops aligned then screw the supports to the bottom. It would act kind of like a hidden apron of sorts. Not completely tool-less but it would be plenty strong.

-- Jarrett - Mount Vernon, Ohio

View sepeck's profile


505 posts in 3224 days

#11 posted 04-17-2019 06:32 PM

So, years ago I was helping sew some pavilions for some friends, I made a table using a plan for a knock down shop table. For the top, I used a large sheet of melamine covered plywood which I trimmed the edges with pine to make it look more ‘purty’. It followed me around for 20ish years in many different uses (also known as the table of doom).

It looked very close to this picture

If I made one today, I’d probably use Canexican's saw horse design for the base

Now I used a full sheet of plywood, but you are doing something temporary, rather then complicate it, just set up your base (whatever you choose) then put the two top pieces on and use gaffers tape on the bottom to hold it together. Should last you the evening easily.

Now, if you want something more long term that ‘folds’ then you can look at this 16c Italian folding table design for the top. Granted, you wanted a split top but I figured I’d toss it in for historical reference and other ideas.

On an unrelated note, looking for those links accidently landed me on the Pinterest rabbit hole which took me an hour to escape.

-- -Steven Peck,

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756 posts in 3230 days

#12 posted 04-17-2019 06:34 PM

View sepeck's profile


505 posts in 3224 days

#13 posted 04-17-2019 07:04 PM

Just watched this on YouTube....

Might help.

- ScottM

Matthias is as always, ruthlessly pragmatic. Where was this 20 years ago? /sigh

-- -Steven Peck,

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756 posts in 3230 days

#14 posted 04-17-2019 07:44 PM

Matthias is as always, ruthlessly pragmatic. Where was this 20 years ago? /sigh

- sepeck

Marbles…. Who woulda thunk it…

View Sylvain's profile


1249 posts in 3582 days

#15 posted 04-18-2019 12:36 PM

I like Matthias Wandel table except that I would use the 2X4 with their width vertically instead of horizontally to minimise sagging.

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

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