Tips for repairing this broken stool?
Hi. This counter stool cracked clean through. I’m quite new to woodworking but would like to try repairing it. I have (or am willing to buy) the essential tools.
Any suggestions on approach?
I don’t think I can stretch the gap open to get glue in there without causing more damage. It’s also not clear how I’d clamp it. I’ve thought about cutting out a section and patching in a new piece of wood.
I'd bet you'll find dowels or loose tenons in each of those joints. The board that needs replacing runs for the backrest to the curve above the front leg; 3 joints total. To repair it cut it away at the backrest first with a VERY thin saw to see what you have. That puts the loose part in your hand.
I would then re-cut for the backrest joint and cut a "loose bridle" joint in both sides of the crack... Effectively a 1/3 thickness spline that can be inserted and clamped after the backrest joint is re-fit.
You could also cut through the front, rear, and leg joints and replace the whole part. I think the repair would look nicer.
That crack doesn't look like it's on a joint.
You could just keep things really simple and chisel out from below a hollow/mortise straddling the break and glue in a wood spline. This would be unseen after. You can create some jigs...scrap wood and clamps... to use to close the joint. Use Liberon wax sticks to fill any crack opening remaining.
That is one strange break. I would try separating it but if it won’t come appart, a spline from the bottom as suggested glued with J-B weld epoxy.
Did it break because the wood is figured, do you think?
Is it solid wood? I think maybe it's veneered over something like poplar ...maybe.... and that is a joint..curved section , straight section,curved section butt jointed, maybe finger jointed? and doweled or not and then veneered over. My bet.... that backrest design puts a lot of stress on that joint. I would attempt to separate that joint maybe with a backward clamp,easy does it like .It might separate enough to get glue into that joint.
Aint anybody ever taught you dont sit on the back of chairs?
I like the new piece of wood idea. There’s a lot of figure there so maybe make it an intentional design detail with a contrasting wood tone or brass or something.
Do you own a dozuki or similar thin kerf saw that can leave a glue ready joint?
If so, I’d try to saw out the crack. Then fit a repair in there. If you make it tight and clean, no clamps should be necessary as the tension in the rail should pinch it. Use epoxy since it will fill any gaps. Leave the repair oversized so you shape it back flush with sandpaper, plane, scraper, whatever.
Might not be the cleanest repair but repairs don’t have to look like they never happened.
Routing a slot for a spline like a couple folks said is a good idea.
Also, before doing anything drastic, definitely try to separate it and see if you can get glue in there. Pretty good chance you can get some glue in there. If you can and the breaks fits back together nicely I really don’t think you need clamps. There’s already tension there. Maybe use hide glue or epoxy since those will stick to themselves in case of failure.
I agree with the splines guys above. It's a break on one side only so it's going to be impossible to separate it enough to drill holes and get a dowel in the center of the rail. Cut a kerf on the bottom side, put a spline in the kerf and glue the break and spline in. Then make sure your guests don't lean back and stress the joints.
Another vote here for a spline - you could use a router to remove a 1/2" wide x 1 1/2" long slot perhaps 3/4" deep on the underside of the crack and put in a piece to bridge it.
I doubt just working glue in would be enough, though it is not impossible.
Have a watch of AT restoration on YouTube - he fixes a lot of things like this.
https://www.youtube.com/watch?v=xj2rAx8cOm8 (just one of his, not necessarily suitable for this project)
Tough spot to get a router under there...
I would use biscuits. They are compressed, so they expand when glued, providing a far stronger joint than a spline. Given it's broken once, I think you want to take your best shot at strengthening it. There are a lot of biscuit joinery tools out there that could easily fit in that space, but I see no reason a router with a slot cutter made for biscuits wouldn't work nicely. Here's what I would do:
Tip the chair upside down so you can access the repair from the bottom. Set the router to insert the biscuits at 1/2" to 3/4" from the edge of the arm, inside and outside (you'll be cutting into the surface under the arm, not on the sides). You may not have enough width to the arm for two, but that would be the best repair. You'll want to get as much of the biscuit into the joint as possible, so set the depth of cut accordingly. Once you have completed the cuts, I am pretty confident you can get the joint apart far enough to get some glue in there, then press the joint back together before gluing and inserting the biscuits. A frame band may work well. If you don't have one, a ratchet style hold-down strap might work also. Either way, wood or c clamps can be used to keep the strap in place so it doesn't slip off the curve on the front of the arm. Once the biscuits are inserted and the glue is dry (24 hrs min), trim the excess with a multi tool or flush cut saw (sometimes referred to as a "gents saw"). Any remaining voids can be filled with epoxy or other wood filler, since the repair will be on the bottom where it won't be visible. Good luck!
I didn't see this mentioned previously, but I may have missed it:
A few options for a quick fix:
1. Clamp a pocket hole jig on the bottom (largest size possible to get close to center of the cross-section at the crack). Or make a simple jig if needed. Then spread the crack slightly open, fill with suitable epoxy and screw together. You can likely find a nice matching plug for the hole. Or do it to both sides and make it intentionally contrasting.
2. You could do a variation of option 1 with a drill jig perpendicular to the crack. Flatten a spot at the drill start to prevent walking, then drill and install/epoxy one of several options: wood dowel, threaded rod, synthetic rod. Then assemble in the same manner as option 1. You would want to maximize the dowel size without making the surrounding wall too small. If the arm is 1.5" thick, maybe a 1/2" dowel.
I have done a similar repair on a weak cross-grain fracture. Easy, hidden, and strong.
Good luck with your fix.
There's an underlying problem - it's a poorly designed chair functionally-speaking. There seems a high probability that a similar crack will occur in the near future, especially now that there's already one crack which, even if repaired, will allow even more stress on the unsupported back rest.
If you want to keep the chair, it might be wise to devise a vertical support piece for that back, running between the back of the seat and the underside of the backrest loop. The problem would then become: what would be an appropriate shape/design for such a support such that it wouldn't detract from the overall look & feel of the chair?
I agree with Lat Axe. Though not exactly (actually, not at all) to the OP's question, the photos and the failure of the structure are a great teaching example of the importance of structural design principles in chairmaking.
To paraphrase somebody, "To fail to design is to design to fail."
+1 on the design issue.
Adding a brace/support roughly in this location might be one option for a reasonable strength improvement without making the reinforcement too complex. You could likely make it blend with the styling as well.