How to make a thick oak wood tabletop

the solid oak tabletop

I recently had a customer that really loved the way we build a thick oak wood tabletop. He saw on our website one of our coffee tables and he liked the way it’s top looked. The top was made from oak wood, without any joints in the length of the boards, boards wide enough so the face of each board can easily be noticed.

After agreeing with the customer the way the tabletop should look, we agreed on a thickness of 4 cm and I started the work.

I had to drive a couple of hours to buy some beautiful oak pieces, around  5 cm thick and 1.1 m long. I have to admit that they were pretty cracked in the middle, but that’s the way local oak is, so I couldn’t do anything about it. Because of the cracks, I had to buy more wood than needed, to make sure I wouldn’t have to drive 50 km again for a small piece of oak.

the oak wood planks from which we will build the thick panel
The 5 cm thickness oak wood planks needed for the project

I did a little re-saw on the planks, to ease the jointer’s work and to save some wear on the knives.

we edged some oak wood planks to be able to make the 4 cm thickness table top
Edging the oak wood planks

I then moved on to the step where huge changes happen: flattening all the boards on all their four sides. As I planed them, I placed them next to each other, until I reached the desired width for the tabletop, 75 cm to be precise. Why 75 cm? Because the tabletop had to be 70 cm wide, but I added a safety margin, to be able to make slight adjustments before gluing everything.

the oak wood planks before planing
We placed the boards side by side to check that the width is enough for the oak wood tabletop

With the necessary boards prepared, I found that I had 2 pieces left out of a total of 7, meaning that I bought around 40% more. After all, it’s not bad, because I still have a few small things to make out of oak.

We started matching the planks, paying attention to defects on the ends, which were not allowed to be in the final tabletop, and to the grain of each plank, so that the final appearance would be as beautiful as possible.

the planks are prepared to build the oak panel
The straightened oak wood planks are placed side by side to check the size of the wooden tabletop

After matching the boards, I drew some lines to guide me in cutting each plank. I chose to cut them at 83 cm for a final length of 80 cm, to avoid small defects on the ends of the planks, usually caused by the planers snipe. Unfortunately, the large planer is not perfectly tuned and still leaves little snipe on the first and last 5 cm. With a bit of luck, I noticed a crack hiding in one of the planks and I was able to rearrange it before cutting the board. I erased the first pencil marks, so that there is no risk of making a wrong cut. Before I moved them from the table to be able to use the saw, I took the time to name each of them, so that I can keep the chosen order and pattern.

drawing the lines for cutting the oak wood panel
We marked the oak wood planks to cut them to the right length
after the tabletop has been sanded on both sides, it is cut to the required size
Marking the oak wood planks to keep the order

After cutting the broken or excess ends, I had to do something I did not really like, but I couldn’t get away without it: I had to set up the planer, in order to be able to fix the imperfect edges. That was also the time to plane all the boards at the same thickness. I made them 4.4 cm thick in order to leave a margin for straightening the panel after the glue dries.

cutting the ends of oak wood planks before gluing them with polyurethane adhesive
The damaged edges or the excess parts of the oak wood planks were cut

I put everything back and searched for possible spaces between the boards in the center of the panel, in case there were concave curved boards. It was not the case, but I saw some spaces on the ends, which meant a convex curvature. I tightened one of the ends with a clamp and I noticed the distance at the other end of the panel. If it is 1 – 1.5 mm, it is not a problem, it can be corrected by tightening. But at one of the joints the distance was more than a few mm, so I had to make another pass through the planer.

the imperfectly planed oak wood planks, at the edges, are planed again to fit better
There was a big gap between these two oak wood planks, so we had to correct it
checking that all the oak planks to fit perfectly before gluing them with polyurethane adhesive
After jointing the boards again, there was almost no gap remaining
checking the oak wood planks before gluing the tabletop
All the oak wood planks are cut and straightened and they are ready for gluing

After all the necessary fixes, I thanked myself for leaving a margin and I moved on to gluing.

For this tabletop a clamping force of approximately 2150 kg (6 kg / square cm, as stated in the polyurethane adhesive instructions) was needed. I have calculated the force of a clamp to about 500 kg, so because of the fact that I only had 4 functional clamps, I concluded that it is not a problem if the total force is somewhere at around 2000 kg as long as the boards are squeezed tight.

I spread the adhesive, using a trowel, so that it covered the entire edge of each board (I forgot to take pictures at this stage, but it is obvious that it was well spread by the way it dripped on the sides) and I tightened the panel with the four clamps. Besides these clamps I used beech runners to correct the positioning differences in height. At 11 o’clock I tightened the last clamp and left the panel to stay until the next day, since on the adhesive bottle it clearly states to avoid any machining for 8 hours after tightening.

the oak wood planks are ready for gluing up
The polyurethane adhesive should only be applied on one edge to joint the planks
the application of the polyurethane adhesive on the edges of the oak wood planks
Applying the glue using the tip of the bottle, before spreading it with a spatula
the oak wood tabletop was glued using large clamps
We used clamps and rectangular bars to avoid any bending
gluing the oak wood planks with polyurethane adhesive to build the thick tabletop
The oak wood panel remained straight after tightening, thanks to the additional bars
when gluing, we used a beech wood plank to get a flat tabletop
The wooden planks are stiffer than the metal ones

After some years of using this method, we designed and made our custom 4-way panel clamps, in order to reduce the time spent with tightening and flattening an oak wood panel. You can find the free plans in there dedicated blog post.

A new day, a new step – the most enjoyable: turning a bunch of planks into a real tabletop.

I removed the excess glue with a very sharp spatula (it cuts similar to a chisel) and I did a few passes with the orbital sander using a coarse 50 grain sandpaper.

after the polyurethane adhesive was dry, the excess is removed and the oak wood table top is sanded
The polyurethane adhesive was completely dry after more than 8 hours
we removed the excess of the polyurethane adhesive
We removed the excess of the polyurethane adhesive using a sharp spatula and some coarse sandpaper
the desk top requires a lot of patience to be perfectly straightened
Even after sanding, the tabletop was not perfectly flat

The counter top came out very well, except that when moving my hand over it, it felt a bit uneven along a couple of the joint lines. So I took the router and used the new straightening jig I had recently done. Although the pictures seem to show very large differences between the cuts, they are very small and after another pass with 50 grit sandpaper, everything was as level as it should be.

our method used in the workshop to straighten the surface of an oak panel
We used the router and a homemade jig to straighten the panel

Another step (I also forgot to take pictures in this stage) was the cut to the final size. I used a piece of melamine board with two perfectly straight edges, cut at 90 degrees, and a handheld circular saw.

I have agreed with the customer that the edges should be rounded on top and beveled on the bottom. Besides the aesthetic reasons, since it was going to become a table, it is important that the edges are not sharp, to make the finish last as long as possible. For rounding I used the router with a roundover and beading router bit, but for the beveled edges on the bottom I only had to use the vibrating sander, with 40 grit sandpaper on it (it acts just like a rasp, but with a textile backing).

the milling drill for rounding the solid oak wood tabletop
Rounding the edges of the oak wood tabletop using a quarter-circle router bit
to obtain a rounded edge, the oak top is rounded with the router and then it is sanded
The fine sanding is required after routing, in order to achieve a seamless rounded edge

After finishing with something intermediate, that is 120 grit sandpaper, I moved on to the knots and small cracks fixing. I used a home made putty, by mixing a water based lacquer and the sawdust left from the initial sanding. You might ask why I did not use other planks if there were cracks in the ones that I chose: Because there were only small surface cracks that did notĀ enlarge even in the temperature variations caused by sanding. But the main reason was the beautiful grain on these boards. Considering the high elasticity of the putty I used and the polyurethane finish, I’m sure nothing will happen. However, I told the customer that if a crack somehow shows up over time he should let me know and I would fix it right away. (It’s been over two years now, and the tabletop seems to be still in great condition, so I was right about these cracks).

the wood cracks are filled with knife putty
The small cracks that we had to fix with wood putty
a mix of glue and fine oak powder to fill the small wood cracks
The home made putty is made out of acrylic and sanding oak dust
the small cracks of the oak wood planks are filled with the mix putty
The cracks filled with our home made special putty

I let the putty harden until the next day, when I made some small corrections where it was needed (at one of the knots on the back, where there was a very large volume of putty that I had to add, some small corrections were needed).

The final finishing followed, with fine 180 grit sandpaper, which gave the tabletop such a perfect look, that I almost didn’t want to spray it anymore, in order to not change it’s beauty. I don’t know how much you can see in the picture because the workshop was a bit dusty, but it looked great:

the perfect finishing of the edges of the oak wood tabletop, before varnishing
The solid oak wood tabletop is ready for varnishing
the thick solid oak wood table top was sanded on both sides
The very smooth surface will help a lot to obtain a finish close to perfection

But a deal is deal, so I moved on to the spraying phase: I washed the gun with some acetone (it is called D1016, but it’s 99% acetone, and it smells horrible, even when wearing a pretty good half face mask). Then I mixed some creepy substances with an equally horrible fragrance, that is polyurethane, hardener and thinner, D1010. Because it was very nice outside I moved the counter top on the balcony and sprayed a pretty thick primer layer. This way I avoided all sorts of stupid methods of ventilating the room and moving the compressor elsewhere so it would not blow up due to the vapors caused by spraying.

the solid oak wood tabletop has been primed
The polyurethane primer was applied outdoors
after the complete finishing of the solid oak wood tabletop, a protective polyurethane primer is applied
The top surface of the oak wood tabletop was the first covered with the primer, so it will be harder when doing the final sanding

After a few hours, when the primer had hardened, I made the final sanding: using the orbital sander and 320 sandpaper for the top and also 320 grit sandpaper for the edges, but using only man power to avoid a too deep sanding. I took care for the primer to be hardened really well, since if it is not completely hardened, the sanding will result in a mixture of dust, something sticky and small bits of sandpaper. This combination might make you start over, which meant that I wouldn’t be able to deliver the counter in time. I was relieved that everything went well with the final sanding, so I prepared the other substances (also with a lot of “perfume”, obviously): a special scratch resistant, with a 20% gloss level. I applied it in a thick enough layer to withstand the wear, but not too thick, in orderĀ to avoid drips that would have ruined everything.

After another two to three hours of hardening, and with the help of the baking paper (since the top was pretty heavy, there was a risk of damaging the finish while transporting the top), I went to meet with the customer. I handed him the tabletop, along with the instructions: “Do not use it until tomorrow”, “Do not put it on anything before covering it with baking paper” and “Take care, it’s pretty heavy!”

how to finish a solid oak wood tabletop with polyurethane varnish
The semi-gloss scratch resistant PU finish
the solid oak tabletop
The detail of a corner of the solid oak tabletop
the oak wood tabletop made out of continuous lammelas
The character of this oak wood tabletop is given by the surfaces of the oak planks that we used

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