Broken Dining - Chairs Need Bracing Ideas

[Brian Kent]

These dining chairs are 21 years old and are heavily used. We have houseguests each week who are on the hefty side (260 lbs to over 300 lbs) and play games at the table for 6 hours at a time.

I have repaired them many times, including several rounds of complete disassembly, cleaning out all old glue. Re-gluing, clamping, screwing. But the forces are strong and persistent on these lightly braced joints.

We are ready to add new bracing to the design, even at the risk of problems in stain-matching or having painted metal showing.

So I am open to your ideas on how to improve the design.

I have 4 other photos that are failing to upload, so I will keep on changing formats and see if I can make it work.

[Brian Kent]

Trying to load more photos

[Mike Henderson]

If you took the chairs apart and did some good loose tenons in the side seat rail to back joints, and you glued them with good glue, AND you put good corner blocks inside the seat area, there's not much more you can do. You could add bracing lower on the chair legs, from front to back and one across those braces, and that will help.

But perhaps the best thing would be to make some more robust chairs for your guest. Make them of a wood like pecan (hickory) and make the back and seat side rails beefy so that you can put in a strong mortise and tenon joint between them. That joint that gets the most stress so you have to make sure that area is very strong. The wood choice needs to be something firm and strong, not wood like mahogany that gives too much.

Mike

[Brian Kent]

Sorry. I have tried about 20 times to load photos that would show the underside. Each joint consists of 2 dowels. Then there is a corner brace which had a finger joint on each side. There is one screw through the corner brace to the leg.

[Mike Henderson]

Sorry. I have tried about 20 times to load photos that would show the underside. Each joint consists of 2 dowels. Then there is a corner brace which had a finger joint on each side. There is one screw through the corner brace to the leg.
Take those joints apart and put in a loose tenon. Two dowels in that joint are absolutely not sufficient - they just do not have sufficient glue area to hold.

I've repaired quite a number of chairs. If you put in a good loose tenon, it will hold much better than those dowels. I never (no far) had a chair come back with a loose joint after I put in a loose tenon in that joint. Use epoxy glue to glue them and leave them in clamps overnight.

Glue in the corner blocks and put at least one screw at each end of the corner block. Two screws (top and bottom) on each side of the corner block is better. Use beefy corner blocks.

Commercial chairs like those are often not well made in that joint.

Mike

[Brian Kent]

Mike, for the loose tenon, this looks like a time that the bead-lock tenons would work well. Have you seen any drawbacks to these?

Otherwise, how do you recommend cutting the mortises? I have usually used a Ray Isles chisel or drilled the mortise and chiseled out the waste. Routers are not my friend unless I have really solid jigs, but I have not made a jig for mortises yet.

[lowell holmes]

Mike is correct.

It just happens that I have some experience with dining room chairs. My daughter and her husband have a dining room suit that the chairs broke down at the dowel joints. After several attempts to re-glue the dowels, I bit the bullet and removed the dowels. I made mortises and slip tenons in the joints. After gluing the slip tenons in place, I put 1/4" dowels through the joints perpendicular to the tenons. The only way for them to fail now is if the wood in the chair fails. Brian, I chopped the mortises with chisels. If you take small bites with the chisel, it's not difficult.

It's been awhile since I did the repair and they seem to be holding.

[Mike Henderson]

Mike, for the loose tenon, this looks like a time that the bead-lock tenons would work well. Have you seen any drawbacks to these?

Otherwise, how do you recommend cutting the mortises? I have usually used a Ray Isles chisel or drilled the mortise and chiseled out the waste. Routers are not my friend unless I have really solid jigs, but I have not made a jig for mortises yet.
Unless you already have everything for those bead lock tenons, I'd just hand cut the two mortises.

The way I'd do it is to take the chair seat side and cut a mortise into it then glue a loose tenon into it. Set aside and let the glue set firmly. Then cut the mortise into the rear leg. Trim the mortise or the tenon so that you get a good fit. If you go too far (your fit is too loose), glue veneer to the side of the tenon.

As Lowell suggested, I'd chop the mortises with a chisel, although I might drill out the area a bit first to make it easier. Certainly, you can drill out the dowels if they didn't come out on their own. Depth is up to you but I'd go about 2" in the side rail. You're limited in the back leg so I'd go as far as I could without going all the way through (just for looks). I don't pin the tenons, just because the pin shows. If you want to pin, I'd recommend drilling from the inside and don't drill all the way through. That way you can pin and the pin won't show from the outside. But I believe a good mortise and tenon with good glue is sufficient by itself.

Another approach I've used is to use the Festool Domino to make your mortises. I find that one tenon is not big enough so I make two cuts next to each other to make the mortise wider. Then I cut the sides of two dominoes and glue them together to make a wider domino (tenon).

You live fairly close to me so if you want to bring one chair (or even a couple) over to my house, I'll work on them with you.

Mike

[ron david]

those types of chairs are made to fail.chairs are also the most used piece of furniture in your house. if you are frequently having those people around, I would suggest getting better built chairs. there is not enough strength at that rear joint to sustain large people when they push back on them esp. if they don't lift their backsides when they go to push the chair back to get out of it. chairs with rungs usually help with the stress to the backs of chairs. most all chairs will have to be repaired for looseness in their lifetime.
good fitting joints are always required and glued properly usually makes a good joint
in those chairs a m & t joint will also fail. epoxy is not the answer. epoxy is no better than any other adhesive if the joint is made and executed properly, but turns the item into a throw away in case of failure. I think that epoxy add confidence to people who are unsure of their skills
ron

[Lee Schierer]

I agree with Ron, it is time to get some more robust chairs for your "hefty" friends. The long lever arm of the back, coupled with the small joint area lends itself to failure when heavily loaded.

[glenn bradley]

The repair as Mike suggests is the first phase of a fix for this. The second is to realize that these are "dining" chairs. You sit down, you eat, you get up, you leave. Gaming table or bar chairs are constructed differently and will take the hours of sitting, shifting,leaning, stretching, etc. that goes on around a gaming or cocktail table. Get some of these and break them out for "game night" and be happy.

[Andrew Hughes]

I also say time for new chairs, here's a nice looking chair in the maloof style. I think its mesquite.

[ron david]

The repair as Mike suggests is the first phase of a fix for this. The second is to realize that these are "dining" chairs. You sit down, you eat, you get up, you leave. Gaming table or bar chairs are constructed differently and will take the hours of sitting, shifting,leaning, stretching, etc. that goes on around a gaming or cocktail table. Get some of these and break them out for "game night" and be happy.
there are dining chairs and then there are dining chairs.
ron

[Mike Henderson]

Just a comment on why I recommend epoxy. As Ron commented, if your joint is "perfect" it doesn't much matter what glue you use - any modern glue is stronger than the wood. But when I'm making a recommendation to someone else, I don't know if they can make a "perfect" joint and epoxy has gap filling qualities. PVA, for example, does not have gap filling capability. So epoxy is a "safer" recommendation.

So why do I use epoxy. I think I'm pretty good at cutting mortise and tenon joints but epoxy is "safer" in case I'm not as perfect as I thought I was. And as far as epoxy being a permanent glue, any glue except hide glue is essentially permanent.

Mike

[lowell holmes]

The chairs I worked on are teak and are heirlooms..

It was not a matter of getting new chairs. If that were to happen, it would be make new chairs.

[ron david]

http://imagizer.imageshack.us/v2/1600x1200q90/673/jmRuKw.jpg (https://imageshack.com/i/ipjmRuKwj)
as the little sign in the shop window says, i did est my business in 1975 and I do work out of a commercial outlet by myself. did have 3 employees and I believe that I let them all go in early 1980. the work wasn't getting done that I wanted done and I despise comebacks. repairs are the main part of what I do. so in 40 years I have repaired quite a few chairs so you understand what has to be done to them so that you and the customer are happy and they don't come back. for adhesives I usually use hide glue. I have always used it and get it 5lbs at a time. if a chair comes in for being loose; it gets completely taken apart and reassembled. all dowells if so it is so equipped get removed and replaced. the other problem today is buying dowells that are up to size so i end up making most of them. Mike stated that I commented, " if your joint is "perfect" it doesn't much matter what glue you use" m but I didn't say that. What I said is, "epoxy is no better than any other adhesive if the joint is made and executed properly, but turns the item into a throw away in case of failure". if you make a joint that is loose you are doomed for failure sooner or later; most likely sooner
people use epoxy because mostly it is quicker and less work. there is a suposedly good millworking shop down the street that make wonderful looking fir exterior doors, when they make them though they leave a 1/16" inch gap at the tenons and fill the spaces full of epoxy upon assembly. they are laid up on a good flat surface so that everything just seems to float level and done. these doors are expensive and if there is ever a problem with them you just replace them.
most PVA glue joint can be loosened by injecting vinegar into them and let sit for awhile. you may have to refesh the vinegar a few times. I also but syringes and needles by the box. you just drill in with a .060" drill bit and put the vinegar in. if you require really fine needles; one of my old Chesapeake Bay Retrievers was diabetic and I saved all of her needles.
to me using epoxy to put chairs together is like having to wear a belt and suspenders at the same time. I don't mean to offend anyone by this. I do get enough chairs and that brought in by previous repairs where epoxy has been used and asked to save the piece afterwards.
here is one of my chairs and they do help in slowing down the racking problem. this one was made in 84 and customer4 still has in use every day
http://i908.photobucket.com/albums/ac281/padresag/furniture/armchair.jpg

and this was a rocking chair that I made for the 1st AAW exhibition at the San Antonio Museum of Art a few years back
http://i908.photobucket.com/albums/ac281/padresag/furniture/cmr2.jpg
http://i908.photobucket.com/albums/ac281/padresag/furniture/cmrdetail.jpg
ron

[Andrew Hughes]

Nice rocking chair Ron,The seat material goes along well with the curl in the maple. I wish others would show more of their work,It's really inspiring.Thanks
Sorry Brian if I am hijacking your thread.🐢

[Mike Henderson]

I guess my experience is different than Ron's. When I get a chair to repair, it's almost always with the two dowels that Brian described. I know that I'm going to replace that, so if I can't get the joint apart by pulling, I'll take a thin bladed saw, such as a Japanese saw and cut through the dowels. Then I rework the joint.

If I ever had a joint fail that had been glued with epoxy, it would mean that the wood failed and the mortise is now too big for the tenon. I suppose an alternate failure could be a break of the tenon but I would think that's pretty rare.

Anyway, since the joint must be reworked, I'll treat it the same as a joint with the dowels. If I couldn't get it apart by pulling, I'd cut the tenon and rework the mortise and tenon.

If the joint was glued with PVA and became loose, I suppose you could soften the PVA with vinegar and pull the joint apart but then you'd still have to rework the joint, or build up the sides of the tenon to fit the larger mortise.

Anyway, I have no problem with using a permanent glue. And I certainly do not see epoxy as making the repair quicker and less work. It's just a choice of a glue - the work and precision of the joint is the same.

Mike

[Let me add that the chairs I get are all commercially made chairs, 20th century, not antiques.]

[Pat Barry]

Hey Ron, why is it you say that you can't repair an epoxy joint?

Seems to me that if its holding together then it doesn't need to come apart and if its come apart then it seems to me you can clean it up, although that also means you need to epoxy it back together - you can't use hide glue, so if hide glue is all you use then you have a problem.

Can you esplain your point a little more?

[ron david]

Hey Ron, why is it you say that you can't repair an epoxy joint?

Seems to me that if its holding together then it doesn't need to come apart and if its come apart then it seems to me you can clean it up, although that also means you need to epoxy it back together - you can't use hide glue, so if hide glue is all you use then you have a problem.

Can you esplain your point a little more?
Pat; I am going to ask you 2 little questions then I will come back with answers for you. I usually don't ask questions but would like to make it clear when I answer you.
What do you do for a real time job?
Do you have a problem reading? you have quoted me as saying, "if hide glue is all that you use then you have a problem". I stated that I "usually" use hide glue. why would I have a problem.
ron

[Pat Barry]

Pat; I am going to ask you 2 little questions then I will come back with answers for you. I usually don't ask questions but would like to make it clear when I answer you.
What do you do for a real time job?
Do you have a problem reading? you have quoted me as saying, "if hide glue is all that you use then you have a problem". I stated that I "usually" use hide glue. why would I have a problem.
ron
I am an engineer and I specify and use epoxies of all types for products we make.
I read perfectly well - your problem is that you only use hide glue and therefore don't appreciate the benefits of epoxy

[ron david]

I am an engineer and I specify and use epoxies of all types for products we make.
I read perfectly well - your problem is that you only use hide glue and therefore don't appreciate the benefits of epoxy
you go back and read it. I realize engineers can't say that they made a little flub; it is not professional. I also may not have the education(formal) that you have, but I sure do know that usually and only are spelled differently. they also have 2 different meanings
the other engineer that has questioned me has also exaggerated what i stated . he said that I stated if your joint is "perfect" it doesn't much matter what glue you use" m but I didn't say that. What I said is, "epoxy is no better than any other adhesive if the joint is made and executed properly,
cheers
ron

[Pat Barry]

Interesting that you have such distain for engineering ron. None the less, I was only trying to understand where you were coming from. For example, on the chairs in question, the ones that precipitated this thread, do you think they were put together with hide glue? I highly doubt that they were, thus, the idea of taking them apart and then using hide glue to reassemble them seems a bit farfetched. After all, my understanding of hide glue tells me that it is not a very good gap filler at all and also is very brittle. While this may be desirable qualities in a new windsor style chair, it is hardly a good solution for a chair that already has loose joints due to previous adhesive failures in the joints. Epoxy, on the other hand has excellent gap filling qualities, and while it may not have the ultimate tensile strength or shear strength of the hide glue, it is a strong adhesive (proper selection of course, properly mixed, properly cured) -Note, I am not advocating the use of 5 minute epoxy for a chair application. Epoxies come in all flavors, for example, at work we have been investigating filled epoxies which have improved qualities such as strength, hardness, thermal conductivity, and adhesion, and there are literally hundreds of potential options on the market from various suppliers, all of which have qualities to be considered in making a selection. These epoxies are filled with other materials such as fiberglass, silica, alumina ceramic, etc that provide key improvements to various properties of the base epoxy. Thus, the engineering aspect of the job is to weigh those properties, understand the tradeoffs involved, understand the proper process requirements to best utilize the materials of choice and get the best performance. This includes understanding the end use of the materials and ensuring the selected one is appropriate. Its not just a matter of saying this is the glue I use, regardless of the situation because that's the way I have always done it.

[Brian Kent]

Let's keep this high on information and low on jabs.

So speaking of information, what kind of epoxy would you recommend for this application. All I have now is the 5-minute variety.

[lowell holmes]

So speaking of information, what kind of epoxy would you recommend for this application. All I have now is the 5-minute variety.

I like System 3 sold by Woodcraft. It's performed well for me.

[Mike Henderson]

Let's keep this high on information and low on jabs.

So speaking of information, what kind of epoxy would you recommend for this application. All I have now is the 5-minute variety.
I use West Systems but I don't know if it comes in small quantities. I have the gallon container of resin. The catalyst (or whatever the second part is called) comes in a smaller container.

I would think that the 60 minute epoxy would be good, but I'll defer to Pat for a recommendation. It looks like he knows a lot more about epoxy than me.

I've used System 3 in the past with good results.

Mike

[ron david]

I do use west systems for some things esp if I need a long open time as in laminating layers and forming, but they do have a lot of writing on the side of the can
1 skin sensitizer, strong irritant
2 may cause allergic reaction
3 may cause severe skin and respiratory irritation
4 avoid skin and eye contact
5avoid breathing concentrated vapours
6 do not ingest
7 use with adequate ventilation
8 use with liquid proof gloves, eye protection and protective clothing
then it gives the first aid recommendations
and then come the bold letters
Keep out of reach of children

I don't think that I see those kind of warning with my dry hide glue packaging
I don't have to be critical about measuring with hide glue just add a little more water if not it will thicken up in a while and I can leave the pot on all day; doesn't kick of a capable of burning you or something else

all that aside I actually use a variety of adhesives , but I mainly use hide glue for joints for various reasons
1 it is reversible and repairable if something ever happens to the piece in the future
2 most of the furniture that I work on used it originally and some of it has been around for 200 or 300 years and has been repaired a few times before and it it needs it in the future
3 it is convenient to me and it has the shear strength of other glues, but doesn't fill in for sloppy workmanship

epoxies are good glues but I believe that the have their places to be used. they are not a forgiving glue. with chairs if you use epoxy and have a joint failure it is pretty well a throw away, or if something else is damaged on the chair and it is required to take it apart to repair. if you have a joint failure; you just can't take one leg off to repair. it usually takes to legs to come off to facilitate a proper repair. epoxies can be undone with heat or sometimes the use of acetone, but what other damage are you going to do in the mean while.
there are also a lot of other glues that are available to assemble chairs and that are ready available. they also have enough strength properties and can be reversible. you don't see manufacturer's assembling chairs and table and that with epoxy.
I believe that most epoxy used to put chairs together is the fear that it is going to fall apart and insecurities about workmanship. if it is of proper construction most normal adhesives that are the market will adequately do the job
If I get any hide glue on my hands I just wash it off with soap and water. if it gets on my clothes it comes out in the wash and doesn't kill my dog if he happens to lick it.
If you are confident in what you do in assembling a chair you do not require epoxy!!!
ron

[John T Barker]

For the chairs I would try a long drying 2 part epoxy. For the guests I would try salads and cottage cheese.

[Mike Henderson]

Another place where I've used epoxy is when I have a very complex glue up that's going to take a long time to get together. The slow West Systems epoxy has a very long pot life - if you place your container in a bed of ice - epoxy generates heat as the components react and the heat speeds up the cure time. Don't ask how I learned this.

But if you mix up sufficient epoxy for the glue up and keep it cool, you'll have lots of time to get everything together. And epoxy is a good strong glue - just more expensive than PVA.

Mike

[West Systems offers at least two catalysts - a slow catalyst and a fast catalyst. In my experience, the slow catalyst means you have to leave the work in clamps overnight.]

[Jim Dwight]

Plunge routers make great mortises. I don't like the noise and it isn't the quickest way to do it but the mortises should be quite precise. It will be quicker than hand cutting them. The primary jig is a simple U-shaped holder with a hole in the bottom so you can put longer pieces in that way.

[lowell holmes]

Plunge routers make great mortises. I don't like the noise and it isn't the quickest way to do it but the mortises should be quite precise. It will be quicker than hand cutting them. The primary jig is a simple U-shaped holder with a hole in the bottom so you can put longer pieces in that way.

In some cases you are correct, the plunge router works great. I have two plunge routers a smaller one and the Dewalt 621. Neither would have been a match for the repairs I did.

In some cases, I just chopped the mortises. In some locations, I drilled adjacent holes and finished with chisels. I also used a self centering dowel jig to drill holes and finished with chisels.

I warm up to do the hand work by chopping practice mortises.

[Larry Frank]

I have read through this thread and there are great suggestions. However, I do not think that anything will work given the nature of the chairs and mainly due to the large size of the people. The chairs were never designed for that loading.

It is kind of like getting the right tool for a job.

I would buy some welded metal chairs for them. Enough is enough....