please critique my chair repair plan

[skeetstar]

Folks, I know this will be really basic for many of you, but I'd like some guidance/approval of my plan to repair some chairs.

They are bespoke made farmhouse kitchen chairs, Elm allegedly, though they don't show much grain. The joints are coming apart due to a teenager (!) swinging back on the rear two legs. Owner had done some repairs on a couple of the chairs with steels screws running front to back to draw the joints together. I plan to;

1. remove all screws from the repaired chairs.

2. gently ease the joints apart and clean off old glue residue

3. Glue joints with PVA

4 plug the screw holes with suitable dowel, probably have to drill them out to a bigger diameter to accept the dowel

5 cross dowel through the tenons from the inside, drilling the holes such that there is no evidence of cross dowelling on the outer faces. Ill only be able to do this on the lower rails/stretchers, and not the seat rails. The seat rail joints will need to be dowelled through the outside faces.

Would 12mm dowels be the right sort of size?

Does that sound the correct approach? Be grateful for any advice that might be forthcoming.

 

[Jacob]

Angle irons in strategic places. Particularly under the back leg to seat joint.

 

[mrpercysnodgrass]

First off, definitely not Elm, definitely Beech.
Your approach sounds fine but I would not use PVA unless the joints are nice and tight and I can see they have machine made mortice and tenons so they are almost certainly not a tight fit. Make sure you get all of the old glue off, a combination of a sharp 1/4" chisel and an old hacksaw blade will do that for you. As for glueing, I personally would use West System Epoxy with their microfiber filler. I know this is an expensive option but you will have two big advantages, 1. The joints will not come apart again even when being tested by an enthusiastic teenager! 2. There will be no need to dowel the joints.

 

[mrpercysnodgrass]

P.S. The chair in the photo has some woodworm infestation so it would be wise to treat that while your at it.

 

[Yojevol]

First off, definitely not Elm, definitely Beech.
Your approach sounds fine but I would not use PVA unless the joints are nice and tight and I can see they have machine made mortice and tenons so they are almost certainly not a tight fit. Make sure you get all of the old glue off, a combination of a sharp 1/4" chisel and an old hacksaw blade will do that for you. As for glueing, I personally would use West System Epoxy with their microfiber filler. I know this is an expensive option but you will have two big advantages, 1. The joints will not come apart again even when being tested by an enthusiastic teenager! 2. There will be no need to dowel the joints.

Agree with Mr Percy

 

[TheUnicorn]

P.S. The chair in the photo has some woodworm infestation so it would be wise to treat that while your at it.

you've better eyes than me, where are you seeing worm?

 

[Fitzroy]

I did an almost identical repair to a chair a few years back to a very similar chair. I used 10mm dowel, I put two in the top tenon and 1 in the lower as it was smaller. However 2 was overkill in hindsight. We hate the chairs and have planned to replace for years so not a careful job. Used Araldite (5 mins epoxy) as joints were very gappy!

The biggest pain was the joints were pinned and glued and although loose l, it was still a pain to get apart.

 

[TheUnicorn]

I was under the impression that epoxy set hard quickly, but that the flipside was it was brittle, do you not need a degree of flex for joints that expect a bit of stress?

 

[Against_The_Grain]

The glue joints look to have quite a large amount of slop judging by the pictures, PVA is good for tight joints but absolutely useless if they are not. If the thickness of the tenon is less than the width of the mortice I would laminate small pieces to the tenon faces and pare down until it is a snug fit in the mortice, that way the glue will stick properly and then proceed with your plan of gluing, screwing and then plugging.

 

[mrpercysnodgrass]

you've better eyes than me, where are you seeing worm?

 

[sawtooth-9]

Don't use PVA - clean the joints and use epoxy.
The result will outlive you !

 

[skeetstar]

Great, thanks all, I'll go with that epoxy option. Yes I see what looks like wood worm flight holes, I'll check them in the flesh, so to speak, and treat as necessary.

Appreciate the input from all who've taken the time to respond, thanks

 

[Richard C-D]

Just to be a bit awkward I'd suggest a slightly different procedure. First thing try to get all the front to back rails and stretcher joints apart, not just the back ones, don't forget to label each part. Try cleaning off the old glue with water, wrap scraps of wet towel around the tenons and stuff the mortices with wet towel. PVA quite often softens when wet and then can be removed. Try not to remove any wood. When clean and dry try test the fit and as mentioned before add thin wood to the tenon if sloppy.
I would use animal glue as it is strong but can flex more than epoxy, it sticks to wood that has been glued with modern glues better than PVA and it can be removed easily and re glued. Obviously the chair should be clamped while the glue sets.
I wouldn't put any dowels through the joints as any force on the joints can split the wood of the uprights. Never put screws or metal brackets on lose joints. Add corner blocks on the inside if there aren't any.
This is the way I've done it for forty years with no subsequent problems.

 

[TheUnicorn]

re. woodworm, that's a lesson for me, I'd have been looking for more of a peppering of holes, perhaps it's too late by then and the damage is done?

 

[glenfield2]

At the risk of incurring the wrath of proper woodworkers I fixed our pretty but not very valuable wobbly dining chairs using Gorilla Glue foaming epoxy glue. Tapped each chair apart, glued, held together again by clamps and straps. Cleaned off surplus foam afterwards. Simple and seems to have worked so far. (Two years on.)
…I’ll get my coat.