# Designing legs for large larch tabletop

I want to make a wide table. For this purpose I bought a larch tabletop with dimensions: 40 x 800 x 2000 millimetres (1.6" x 31.5" x 78.7"). This tabletop according to my computations is about 50kg (110 lb) based on information I found that larch is about 700kg per 1m3.

Previously I thought about buying some height-adjustable legs from Ikea and mounting them simply with screws. But recently I thought that for such a heavy tabletop it wouldn't be enough.

So I searched online for some time and came up with this custom leg scheme (this is 1 pair of legs):

So the basic idea is to have 2 pairs of these leg assemblies and cut 4 corners from the tabletop for legs to fill them in. What I am not sure about is what dimensions for A, B, C, E should I use for whole construction to be sturdy (taking in account, that there will be weights on the table, ideally I want be comfortable with 2 80kg person sitting on the table).

Also, I have some concerns about wiggles along the wide side. Maybe I should add some connection between the assemblies (along the wide side), though not in this solution because it will take place under the table or require extra work to make panels embedded into wooden tabletop.

So can I use legs like this for such a tabletop?

• "So the basic idea is to have 2 pairs of these legs and cut 4 corners from the tabletop for legs to fill them in." Definitely don't do that — see first bullet point in @Ashlar's Answer. There is no fundamental problem with metal legs used for a solid-wood tabletop, as long as the mounting method allows for expansion and contraction. Have a search here for "tabletop" and "movement" and you should find numerous previous Answers which can guide you towards an appropriate way to attach a wide tabletop like this to whatever legs you eventually go with. Commented Dec 30, 2019 at 9:11
• For these legs, are you a welder, were you going to make them yourself? Commented Dec 30, 2019 at 9:47
• @GraphussupportsMonica Most likely I would make an order in local metalworking workshop Commented Dec 30, 2019 at 9:57
• OK in that case they could install brackets for you on the inside edges of the legs. These will be for screws to hold the tabletop. The screws won't go through simple drilled holes as that doesn't allow for movement, instead there should be short slots (10mm is probably long enough but have them make them longer) for the screws to ride in. This way they can slide back and forth as needed during changes in the width of the top as the moisture content of the wood changes through the year as humidity goes up and down. Commented Dec 31, 2019 at 7:56

A table may look simple, but there are some important points to keep in mind when designing one:

• Wood expands and contracts across its width and depth, but not in its length as a result of seasonal humidity etc. This means that if you notch the corners to accept the legs, while the width of the top will expand the legs will not because they are connected by the horizontal cross piece of your leg assembly. This will lead to a great deal of stress on the leg frames that could lead to big problems over the seasons. It would be better to build a table leg frame and fix the table top to the leg frame with wood buttons or metal table top anchors.
• The horizontal brace on the leg frame is very necessary. You will also need one that connects each side of each leg assembly to the other one creating a three dimensional frame.
• The horizontal braces (aprons) must be connected to the legs securely to prevent the legs from racking due to moving the table or putting uneven loads on it. This is often accomplished by creating glued mortise and tenon joints. There are other ways as well,but for a heavy table that people may sit on you want those connections to be very secure. (I would recommend at these aprons be at least 20mm x 80mm). Remember that you must be able to sit with legs sliding under the aprons comfortably so take that into account in your design.
• The legs should be at least 60x60mm which would be more than adequate for strength and thick enough to accommodate 20mm wide tenons centered on the leg. Beyond that you may want them to be thicker or taper for purely aesthetic reasons.

I recommend that you do a little research by looking closely at tables constructed by other woodworkers (not the ikea out of the box kind) and study how they have done it. There are also a lot of related questions on this site that you can search for by a search subject or selecting specific tags such as tables and joints.

• Thanks for detailed answer. While reading mortise and tenon part of your answer I thought that I've missed one point in my question. Legs will be made from metal with use of welding. Will your points apply for this? Commented Dec 30, 2019 at 2:46
• Steel legs will not allow for expansion of top either. You will need some type of screw connection from legs to table top that allows for expansion. Figure 8 table top connectors should do the trick.
– Ashlar
Commented Dec 31, 2019 at 3:57