How to fix a swivel chair with a cracked seat.
Someone gave me a swivel desk chair, 7-way adjustable, either $350 or a cheaper imitation of $350, probably the latter since I can't find a brand name on it. This is what it looks like:
Someone sat on one arm (moron!) and broke the wood or wood-like bottom to the seat cushion, so that the left part of the seat sags when I sit on it, and the left arm tips away from me when I put my arm on it. The arm only tips because 1/3 of the seat backing bends down
I do need a desk chair, so I want to splice the seat backing.
I hope you can picture the situation. Still pictures won't help much. You all know what the underside of a desk chair looks like and you can imagine that where the arms attach is about 4 inches deep and 6" wide, on each side.
The break line is available for repairs in the rear third or half of the seat, but, not surprisingly, in the front it broke right next to the bracket, the sort-of flat plate, 6" x 6", that holds the seat to the seatpost, However the plate protrudes down 3/16" at the corners where the screws are and there is a 3/16" "slot" for almost 4" between the front and rear corners of the plate. It looks like I can slide something underneath in the middle.
So what would you do to fix this?
The bottom of the seat is covered in cloth. I could remove that now to make my plan but I'd rather have a general plan first.
What is the basis, the backing, of the cushion probably made of? Plywood? Masonite? And how thick is it?
Assuming it's wood, or plywood, I could get a strong piece of wood and set the grain perpendicular to the break, and use screws to attach it, but would screws stick in the backing or is that so think they would they rip out.
How much could they stick out the top of the backing before they stuck into my bottom when I sat down?. I'll get someone else to sit in it when I can, to measure, but do you have a guess? Or I can talk off the cloth and glue the splint to the original wood.
Or I could use a steel plate or a few flats.
The flats might slide under the metal seat attaching plate and they might not need any more attaching than that at that end. At the other head I'd use round-head wood screws. Although maybe the increasing diameter of wood screws is a bad idea in this case, because since the backing is so thin, once they loosen at all, they'll fall out. Maybe sheet metal screws, although their pitch is smaller. ???
Or a steel plate. How thick? A plate would need cutouts to make notches for the rear attaching area of the seatpost plate, and for the area where the arm attaches.
Or a combination. Steel flats in front of the arm rest slid under the seat bracket, rammed in place and they wouldn't need attaching to the currently sagging part of the seat because all the forces would push the seat down on to the metal, and nothing would separate them.
And behind the arm rest, some fairly thick wood slid in via a cut in the cloth, covered with glue on the top side.
Most of my weight is probably in the middle 6" of the seat, which is still good, but some is pushing down a bit to the left of that. The repair only has to be strong enough to hold that up.