I hope this is okay to post here. If not, let me know where I should go.
I built a standard table using mostly scrap wood. The top is a very nice piece of half-inch plywood, attached to 2x4 apron surrounding the sides. Legs are screwed into the apron (not mortise and tenoned because I was lazy). I’m typing on it now with a laptop and seems sturdy now but when I put my monitor setup, it becomes very top heavy. Since I tend to “pull” on my desk to move my chair, it would likely topple, which would be very bad™.
I’ve been frantically searching online of ways to counter-act this and methods don’t seem clear as to how they work. For example, some woodworking websites suggest adding cross braces across the legs. The page doesn’t explain why this works. I am guessing it spreads the force of weight across the braces towards the back legs?
I also found some plans that show a rising standing desk. Ignoring the moving parts, I saw that the legs were parallel to the desk, joined by what I’ll assume is mortise and tenon. This plan seems a bit more doable with the tools I have, and has a similar shape.
My monitor stand also functions as a rising desk and MUST sit on the front of the desk. So the apron is set back roughly 5 inches in the front so that it can clamp in. I estimate it’s roughly 20 pounds with the monitors on it. I know I could just buy 20 pounds of weight and put it on the back but given that tables should be tables, I figured I would ask here for suggestions.
I’ve got family stuff today and I’ll try to reply as I am able. Thanks in advanced.
Any pictures? Cross braces on the legs are meant to stabilize them and keep them from flexing. It adds a lot of strength so I would highly suggest it. Put the braces about a third of the way up the legs and that should help. You could also consider adding a bottom to the desk legs that ties the two left legs together and two right legs, and comes out further to the front than the legs do. You’ll have to be careful about tripping, but some angles braces at the front going up to the legs could make that a little less likely.
I think I see the problem, if I understand correctly the building of your desk. The dimensions are alright, I’m guessing the table itself is not very massive/heavy and, by what you said about the apron set back on the front, the front legs are, also, set back those 5 inches which already put the centre of mass quite high and to the front. Adding the monitors and stand worsens it, moving it higher and forward, barely to the edge of the rectangle formed by the legs. Also, you’ve mentioned the legs move slightly, again moving the centre of mass further to the front. This flexibility in the joints, and probably also the monitor stand, means that if it tips past a certain point it will tend to tip even more.
So the solution imo—given that moving the weight back is not an option—is to move and/or angle the front legs to the front, reinforce them in the shape of a triangle and maybe brace them better to make the whole structure sturdier, any giving in the joints will make it tipsier. The last detail that could help, but very slightly probably so not a solution by itself, is how well your chair rolls, and how fast you want to get closer to your desk.
Omg you explained this very well. I didn’t take into account that moving the legs back would move the center of gravity.
God damn it. Physics! You bitch!
I think the triangle approach is not possible. I am beginning to wonder if my approach (e.g. table with an apron) is the wrong approach.
You can add a horizontal span where the legs meet the floor to help make it a bit more stable thanks to a wider base. Think something similar to the upside down Ts on some standing desks, but instead of one vertical riser you would have two.
It could be as easy as screwing some scrap wood at the base of your existing legs that produces out the front 5-6". Depending on where the desk is and if they would be a hazard you could go even longer.
So, wild thought. If you can’t brace from the front to prevent tipping, the other option would be to lock down the back. It also sounds like you need a smoother surface for your desk chair.
What if you laid down a sheet of plywood and attached the rear legs to it? If the rear legs can’t lift, the desk can’t tip to the front.
What are the dimensions of the table? Do the legs move when you pull on it, or does the whole table rotate/shift? I’m trying to understand if it’s the legs wobbling or the table itself. If it’s the legs, bracing will likely help a bunch to solidify the frame.
The dimensions are w: 25" x l: 48" x h: 30"
The legs move slightly when pulled (it could be sturdier and the brace would certainly help with that) but the whole table shifts. If I pull with the monitor stand on it, the table would fall over.
Given that the legs move a little bit, I would suggest adding at least a small amount of bracing in addition to whatever you choose to do to fix the center of gravity problem.
Also, bracing helps to stiffen the structure by resisting forces that would make the wooden rectangle into a parallelogram. Here is an illustration:
Can you anchor it to the wall?
I would prefer not to. I could but it would only be on one side of the table.
In that case, (I think) the problem is you pulling on it. Those dimensions feel really reasonable. I think you’re saying that without the monitors it doesn’t have this stability problem, but do you pull on the table the same way without the monitors on it?
Something that would potentially help me in this situation is a beam from leg to leg across the back near the floor. It’ll provide a little weight, but also let you use your feet to either counter balance the pull, or in my case, I would be moving myself using my feet and that bar. If you have clamps, it’s easy to try out with scrap wood of the right length.
You are correct: with nothing on it, the table is fine. But with the weight of the monitor stand near the front, pulling my chair causes the table to tip.
Based on comments and other drawings I’ve seen so far, I’m thinking you’re right. I’m going add a crossbeam across the legs (the two sides and in the back).
My goal was to build the desk with subpar wood so there are some twists and cupping in the wood. So getting every square is a challenge.
A quick (maybe not elegant) fix is to add stretchers to the bottom, along the short sides. Then add weight (like sandbags) over the stretchers to bring the cg down.
