Monday, 13 June 2016

Upgrading an X-trestle table, part 2

This post continues the story of enlarging/upgrading an X-trestle table of the previous post. I wanted to add a rim to our X-trestle table in the style of the medieval trestle table top in the 'Onze Lieve Vrouwe ter Potterie' museum in Bruges, Belgium. There, the parts of the rim are connected with a mitre joint. The actual joint is hidden, but the wooden nails used to fasten the joint can be seen at the underside of the table.

 Left: the underside of the Bruges table, where you can see the dowel pins to fasten the mitre joint. Right: the top of the Bruges table, between the rim and the middle of the table is some space to allow for wood movement.

Adding a rim means that the sides of the original table had to be squared. As this proved to be difficult to do with the table saw, the table top was sawn into four planks that could be easier handled. These were then glued again to each other. The thickness of the table was reduced from 5 to 3.4 cm, the thickness of the planks bought for the rim. The width of the rim was 11 cm.

 The re-glued and squared tabletop with the planks for the rim.

The rim and the original table top were to be connected with a tongue and groove, so a groove had to be cut. This was done using a router. Some extra space (3 mm) was given for the movement of the wood.

A 12 mm groove was cut at the edge of the tabletop with a router.

Left: Cleaning the groove with a hand router plane. Right: The table top with one added rim. A loose feather connects both. The feather was later glued into one groove.

The 45 degree mitres of the rim were cut with a drop-saw. A flat, loose tenon was used to connect both sides of the mitre. For this, in each 45 degree mitre a mortise had to be cut. Also here a router was used. A double screw vise (a modern version of the medieval double screw vise) clamped to the rim was used as a stable platform for the router. The router used to side supports, gliding over the screw vise, allowing only side movement. Then, side movement was blocked by two stops, thereby ensuring an exact measurement of the mortise.

Left: The double screw vise is clamped to the 45 degree angle of the rim and rests on a portable workbench. 
Right: The router has two side supports sliding along the double screw vise.

Left: Two stops ensure the maximum length of the mortise. The width of  the mortise is set by the width of the cutter. 
Right: Cutting with the router in process.

Cutting the mortise on the long rim was more problematic, as it did not stably fit in the portable workbench. This time the rim was clamped against a wall table. The portable workbench was now needed as a platform to stand on while operating the router.

The stretcher connecting the X-trestles with the tabletop were originally secured with brass screws to the table top. There is, however, a much better and more medieval way to secure this stretcher to the tabletop. This is a sliding dovetail, which also allows for movement of the wood. A sliding dovetail can for instance be found on the X-trestle table shown in the previous post and on a kitchen table in Chateau Martainville (France). The sliding dovetail used for my X-trestle table is in turn fixed by the rim of the table.

Left: The medieval kitchen table of Chateau Martainville, Martainville, France, with a sliding dovetail for the legs. 
Right: Detail of the 16th century X-trestle table showing the sliding dovetail.

The stretchers with the dovetails made on a router table.

Using the router to make the corresponding dovetail groove in the tabletop. Eventually a little wax was needed to be able to shove the dovetail stretcher in.

The stretchers were cut to the size of the tabletop with a 60 degree angle. Here you can see the difference between the blank oak of the tabletop and the 'aged' oak of the X-trestle.

Try-out of the dovetail stretchers with the X-trestles.

Now the tabletop was ready to be assembled. The loose tenon for the mitre joint was glued (which is essentially unnecessary). A jig was used to drill the four holes for the wooden pins of each mitre joint. This ensured that the holes were at exact the dame places at the four corners of the table. 

The table assembled, just before the wooden pins are added. 
The new stretcher to connect the two X-trestles can be seen on the left side of the table top.
Left: A set triangle is used to define the place of the drill jig. Right: The mitre with the four pins.

The next step was to adjust the X-trestles, the wedges and large pins to the same style as the rest of the table, e.g. making them blank oak again. For this scraper (for the large flat surfaces) and sanding machine (for the smaller and curved surfaces) were used.

Scraping and sanding the X-stretchers clean.

Also, a new larger stretcher connecting the two X-trestles was needed, as the two sliding dovetail stretchers were set further apart (necessary due to the enlargement of the tabletop). This stretcher is secured by wedges to the central point of the X-trestle. Finally, the table received three coats of linseed oil as protection against regular use as dining table. The finished table now measures 196 by 97 cm.

The underside of the table gleaming with linseed oil. The new stretcher (also oiled) is on top of two blocks to prevent it sticking to the table top.

The X-trestle is secured by two large pins to the table top, while the X-trestles are fixed with a wedge to the horizontal stretcher.

The final upgraded X-trestle table together with different X-type chairs and a strycsitten, ready for a medieval dinner.


  1. Looking good. I guess you have a floating spline in your mitre joint? Is that how the Dutch original is? It is difficult to tell from the photo you presented, but i am sure you inspected it and have an idea how it was made. By the by, those are very medieval looking tools you have used to make it;-)

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  3. Uwielbiam tu zaglądać bo zawsze jestem mile zaskoczona ! Podziwiam i pozdrawiam cieplutko <3