Trestle Dining Table Revisited (completed)

[derekcohen]

Time to re-visit the dining table, and move in a new direction. I have design, this time, a trestle table. The design is aimed at complimenting the (DC 09) chairs. To do this, in part the table legs must reduce clutter, which is the advantage of a trestle table ... the legs are tucked out of the way.The base is to be Jarrah, which is a particularly hard and stiff wood. I have used in in many builds, as many are aware. One of the advantages this has given me is the option of building with thinner stock. All the trestle tables I have seen come with rather chunky legs and stretchers, and this is not the aesthetic I prefer.

I have made up some basic drawings and plans, but nothing I want to show here. Instead, I am posting photos of tables I found which have similarities - this is just to offer up some concepts to aid in visualising what I am planning. My design is different in important areas, but there are indeed similarities ...Here is a table made by Borge-Morgensen, which has similar dimensions for the parts. The construction is very similar.





The top will be made from Rock Maple, and 1825mm long (72") x 900mm (35") wide, and 30mm thick. At present my first choice is to use a shallow elliptical router bit, creating a pillowed (very slightly rounded) face to soften the edge. This is in keeping with the chairs, which are all curvy. The second choice - if this leaves the top looking too thick - is to use a shallow undercut chamfer. Note that the top will be curved along all sides.Something like this Nakashima table ...



The legs link to the chairs through an oval shape I plan to give them (the legs of the chairs are oval) ... both in the horizontal and vertical parts. Joinery is pinned loose mortise-and-tenon and not the bridle joint in the Nakashima photo.The light Rock Maple top will appear to float on the dark Jarrah base. That is the intention.

A comment about the DC 09 Chairs I built: When we were planning to build a larger table, it was necessary to add two more chairs. My initial thought was to find bentwood carvers to join the existing bent wood chairs, but we did not like their looks, and went searching for something else. Much of our furniture is contemporary, Mid Century-styled (as you may have noticed from my builds), and so I decided to add two modern carvers (we do not mind a mix-and-match), and use the table to blend all the pieces together.



I managed to do a little work on the trestle table in between watching the Olympic Games.

The mortise and tenon joinery is all loose tenons, which is easier to do accurately since all are through mortises. Plus I can orient the grain in the tenons for maximum strength (i.e. no run out).



With the exception of the cross support, all mortises are 1/2" x 70mm wide x 40mm deep. The cross support mortises are 1/2" x 40mm wide x 40mm deep.



The loose tenon stock is made simply and quickly: thickness quarter sawn Jarrah, saw to width, and round over with a 1/4 round bit in a trim router.



One correction for the loose tenons: the loose tenon is actually 80mm (3 1/8") long. The root is 40mm. And will be pinned at each end. That is pretty substantial. The rail will be wedged.

Regarding the choice of loose tenon joinery in this build: I have a preference for traditional mortise-and-tenon joinery. When I started making the chairs, this is what I did - integrated tenons from the seats. Then it became evident that they were vulnerable to breaking owing to run out. That is not a risk to take with chair legs. I started again, and this time used loose tenons, which allowed me to choose quarter-sawn stock.

The wedged M&T legs ...

... need to be echoed in the table. Hence the round ends (made with a router) in the table legs. Also the oval table legs linking to the oval chair legs.

Now we get to the interesting part. What I start with will be quite different from what ends up finished. There is very little that will not be carved away. Remember, the table is intended to blend with the two chairs I built. For this reason, the two vertical sections and the horizontal cross support will be oval in cross section. I have not seen this before ...



A template for later use ...



All the base parts cut to length and width, and mortised ...



A loose fit. There is just over 1m (40") between the trestle ends, with a 16" overhang planned. 72" long in total. Note that the top support is wider than the base. Both will be carved away for an "organic" blend with the upright sections. It looks a little stick-like at present ...



Here is one leg or, rather, one upright. Everyone likes looking at shavings and planes. Start with a jack ... in this case a Stanley #605 with a radiused blade ... follow with a HNT Gordon Trying Plane to remove any tearout, and more shaping with smaller planes ...



Planing down to the marked curved lines ...



The tiny high angle BU smoother I made worked its magic ...







Time to turn that thick blocky base into a shapely, organic foot for the post.

It needs to be said that I binned the first feet I shaped as they ended up too thick looking. I want slim. I realised that a reason for this was that the blocky base was not wide enough (at 80mm), and so I built new ones, this time 110mm wide. In the photo below, the first is being shaped with a scrub plane into a half-ellipse to match the posts ...

This was followed up with a trying plane ...

Prior to shaping the base, it was drilled for the dowels which will later be used to draw-bore the mortise-and-tenon joint ...

The feet are too thick, and this will be reduced with a taper. Below the beginning and end is marked out ...

A succession of woodies are used (as was done in shaping the curves). First a scrub plane removed the bulk of the waste. This produces a rough finish ...

This is followed by a jack plane, which has a less aggressive radius to its blade ...

A trying plane now smooths out the surface ...

Finally, a smoother is used for the finish ...

It is relevant at this point to recall that the table top with be curved at the sides and ends, similar to this Nakashima ...

The ends are marked with a slight taper, about 8mm each side ...

This time I used a Stanley #604 with a close chipbreaker since it handles reversing grain best of all ...

The end curves were marked ..

... and the waste removed with a block plane.

This is combination after sanding to 400 grit ...

Hopefully, tomorrow may see the trestle table base completed.

Regards from Perth

Derek

 

[six-point socket II]

Wow, that is an interesting build. I bet it’s going to be a spectacular table when finished. Love the amount of hand shaping with the planes. Not that I have build anything to this extent, but I gave a few of my hand tools a little work out on my latest project and the amount of joy and inner peace it gives me is just unmatched … I guess it must be similar for you when that rectangular piece of wood takes on the curves and desired shape. Thank you for sharing all those detailed pictures!

Kind regards,
Oliver

 

[Crazyraceguy]

That looks really great Derek. I like the design and the choice of wood. The lowering of the trestle is a nice touch too. I see a lot of them that are so high that it compromises stability.
Are you going to do all of that shaping to the upper mounting rails?

 

[smorgasbord]

Nice build. Some comments, though:

1. The second & third paragraphs are the same.
2. The “Nakashima” table looks to be a Nakashima-inspired table, not a true Nakashima build. Not that that matters.
3. Are you worried your nicely ovaled uprights will be weak at the joints? The corners of the mortises look very close to the outside edges. In retrospect, I would have reduced the tenon thickness and maybe width a tad, too.

 

[Crazyraceguy]

1. The second & third paragraphs are the same.

I saw that too, thought I was losing my mind. I bet some copy/paste action was involved there  [big grin]

 

[derekcohen]

...
Are you going to do all of that shaping to the upper mounting rails?

Yes ... coming shortly.

Regards from Perth

Derek

 

[derekcohen]

Nice build. Some comments, though:

3. Are you worried your nicely ovaled uprights will be weak at the joints? The corners of the mortises look very close to the outside edges. In retrospect, I would have reduced the tenon thickness and maybe width a tad, too.

It could only be weak if there was movement, along with side-to-side and front-to-back racking. There is both a central rail and a table top to pull all into further rigidity. Plus, the wood is Jarrah - very interlocked grain and hard wood. I am confident the construction will last many years.

It is an interesting issue. I see so many builds that are overbuilt. This seems to me to be a feature of US furniture building, where cabinets and drawers are really bulked up. Look at quality English and Australian work for a contrast. My aim, from the start, has been to build lightly-but-strongly, maximising the aesthetic.

Regards from Perth

Derek

 

[derekcohen]

1. The second & third paragraphs are the same.

I saw that too, thought I was losing my mind. I bet some copy/paste action was involved there  [big grin]

Sorted ... think of it as a stutter

Regards from Perth

Derek

 

[derekcohen]

The last two structural areas for the base were the central rail, which was also planed into an ellipse ...



... and the upper, support rails ...



These also required tapering, which I shall not go through again here. Instead, I will move to the completed - but dry and unfinished - trestle base. I would have preferred to have it all done, but the weekend came to an end. Rats.





These will provide some idea of the curves and, hopefully, organic feel I was aiming for ...







Regards from Perth

Derek

 

[smorgasbord]

It could only be weak if there was movement, along with side-to-side and front-to-back racking. …
It is an interesting issue. I see so many builds that are overbuilt. …My aim, from the start, has been to build lightly-but-strongly, maximising the aesthetic.

Movement won’t be the cause, but an indication of joint failure. There are YT videos testing joints, and failure from too thick tenons is a thing. Probably OK under normal use. 

That said, right-sizing the tenon wouldn’t affect the visible proportions of the table.

 

[derekcohen]

The numbers are different from the impression taken from a photo.

The section is 30mm wide. The mortise is 12.5mm wide, where a 1/3 Rule would advocate 10mm. The extra thickness if the tenon adds to stiffness, and the thinnest section of the shoulder is 8mm thick. Does that sound weak?

Regards from Perth

Derek

 

[smorgasbord]

The numbers are different from the impression taken from a photo.

The section is 30mm wide. The mortise is 12.5mm wide, where a 1/3 Rule would advocate 10mm. The extra thickness if the tenon adds to stiffness, and the thinnest section of the shoulder is 8mm thick. Does that sound weak?

Honestly, it looks weak. Here’s your photo, annotated:
[attachimg=1]

The blue lines show your 8mm mortise wall thickness.
The red lines show the weak spot, where the upright might split under load. That looks to be closer to 5mm, but even 6mm is far weaker than the tenon it holds.

Again, I agree probably not a problem under normal use. 

 

[Mini Me]

Unless you have worked with Jarrah you would find it difficult to appreciate how hard and strong it is. The proof will be in the pudding but I would back the Jarrah myself.

 

[derekcohen]

The numbers are different from the impression taken from a photo.

The section is 30mm wide. The mortise is 12.5mm wide, where a 1/3 Rule would advocate 10mm. The extra thickness if the tenon adds to stiffness, and the thinnest section of the shoulder is 8mm thick. Does that sound weak?

Honestly, it looks weak. Here’s your photo, annotated:
[attachimg=1]

The blue lines show your 8mm mortise wall thickness.
The red lines show the weak spot, where the upright might split under load. That looks to be closer to 5mm, but even 6mm is far weaker than the tenon it holds.

Again, I agree probably not a problem under normal use.

This is an interesting issue, so I will add a little more of my thoughts. Yours are very welcome.

Back-and-forward movement is not going to occur as the central rail and the table top will lock the legs in the vertical. This will remove the concern about the 8mm mortice thickness being weak.

Your concern is the 5mm thickness at the corners of the mortise. My understanding is that downward force on the table top creates potential side-to-side movement. Where the strength is needed is at the ends of the mortise, and there it is about 18mm thick.  Don't forget that the root of the tenon is 40mm, and then the tenon is pinned as well. There should not be any lateral movement inside the mortise to stress the walls.

The base is especially solid, with not only a deep root, but is double-pinned. This should be especially rigid.

As MM wrote, "The proof will be in the pudding ..".

Regards from Perth

Derek

 

[six-point socket II]

Beautiful base!

Kind regards,
Oliver

 

[smorgasbord]

Your concern is the 5mm thickness at the corners of the mortise. My understanding is that downward force on the table top creates potential side-to-side movement. Where the strength is needed is at the ends of the mortise, and there it is about 18mm thick.  Don't forget that the root of the tenon is 40mm, and then the tenon is pinned as well. There should not be any lateral movement inside the mortise to stress the walls.

This is all academic, but I do feel there’s value in discussing joint internals for strength. If the top upright joint were to fail, it might be from someone sitting on the long edge of the table. That essentially cantilevers out by half the width of the table. That would put compression on the side of the tenon closest to where the person is sitting and tension on the other side of the tenon.

The center pin would, of course, resist the joint separating, but there the mortise walls are 8mm versus the tenon at more than 12mm. If the glue were needed to hold it together, then the far side of the tenon might blow out the upright at the thinnest part - the corners. This is essentially across the grain, relying on wood fiber adhesion for strength, which is the weakest direction of wood.

Not that this will happen, but I personally would have used a thinner tenon. Since I own a DF700, I’d probably have put two 10mm dominos in there, as long as I wanted. And I’d look to space them such that there wouldn’t be as thin a corner of mortise to upright.

If one really felt that a thinner Jarrah mortise wall is as strong as a thicker domino, one could use 12mm dominos, again adjusting the spacing to not produce thinner corners.

But again, you’ll probably be fine.

 

[derekcohen]

A quick video demo of how rapidly elliptical shaping can be done with hand planes (and that more of the power side may wish to incorporate these into the work flow) ...


That is unlikely to gain any followers to my channel!

Regards from Perth

Derek

 

[derekcohen]

I have always found glueing up far more stressful than cutting the parts and planing them to fit precisely. My fear is always that something will move and the result will be a mis-match of parts. The additional concern is that the joinery may not be strong enough, and that my insistence on not over-designing joinery will prove that I am a hopeless amateur.

An important feature of the mortise-and-loose-tenon joinery is ensuring that the tenon does not move. Glue alone may suffice, but I have added 3/8" diameter pegs or dowels. Now I recently purchased a dowel maker on Temu for the grand sum of $19 AUD. How good could this be? Well, in short, it is pretty damn good, to my surprise.



But it would be the wrong way to make pegs/dowels for these joints. That jig make great dowels for filling holes, but for pegging tenons you need grain that does not have run out, is straight and strong. This means making pegs from rived stock. This was then pounded through a LN dowel plate ....



The peg holes had already been drilled in the base and upright, as shown previously. The loose tenons were glued into the bases and upper stretchers (but not the vertical stretcher yet). Now the holes were extended through the tenons ...



... the excess sawn off ...



... and the stubs sanded away ...



Sanding is the better choice here of using a chisel since the dust will fill any gaps in the pegged holes. Just add glue and sand flush.

Once the base and upper stretchers are complete, the vertical stretcher can be glued and clamped, first to the base ...



... and then the upper stretcher is added ...



While clamping all together, the level is checked to be parallel. This was found to be within 0.05 degree. Happy with this.

The loose tenons for the cross stretcher are sawn for wedges ...



The tenon is shaped for later ...



The wedges are sawn roughly to shape, and then planed to match each other using a simple fixture made for the purpose ...



Before the cross stretcher is glued, the underside of the bases are given protective pads (made from Crubber). These raise the ends about 2mm, ensuring both stability on the floor as well as a non-slip ...



Finally, the cross stretchers are added and the ends clamped together ...



Attention and time was given to ensuring all was perfectly square, and remained so once clamped up ...



The first coat of Whittle Evolution hard wax oil (Classic) was rubbed on. A second coat was added a day later. The colours in this Jarrah just popped out ...







Returning to the design of this trestle table base, the aim was to build something to meld with the DC 09 chairs I built. How have we done?  Keep in mind that the table top will be Rock Maple.



The elliptical sections of the trestle base hopefully match the legs and arms of the chairs ...



Lastly, with regard the strength and stability of the slim sections in mind, I tested this by pressing very heavily on the ends of the upper rails. They did not budge  [smile]

Regards from Perth

Derek

 

[six-point socket II]

Thanks for the update, it’s really a beautiful build!

Kind regards,
Oliver

 

[Crazyraceguy]

Wow, that really is fantastic.  [eek]