See if you can figure out what they are made of such as maple, Oak or Pine.
Go to the lumber store and buy some 2" x 2" lengths in the same kind
of wood. Cut the 2" x 2" longer than necessary.
Turn the 2" x 2" 's down to match the posts that are now in the
back of the chair. Once you have what you need to replace the back of your old
wooden chair then cut them to the required length.
If you are replacing the rungs between the legs you will want them to
match. Try taking a good one out and use that as your example for length and
design. This will keep your old wooden chairs looking all the same. A good tip
is if you need to cut anything of the new rung make sure to cut the same
amount of both ends,. This will keep the pattern in the middle.
You will need to buy some glue. A good glue is titebond. This glue dries
clear and is waterproof. Some people say do not use wood clamps go to an old
tire shop and get an inner tube. One that is not in too bad of shape. Cut the
inner tube into lengths about 1" to 1 1/2" wide strips the length of
the tube. Now once you have glued the rungs to the old wooden chairs wrap the
rubber strips around all four legs and tie off. This will hold your rungs
tight until the have dried.
Now glue the slats in the back of your old wooden chair taking the rubber
strip and leaving 6 " or more on top of the back of the chair so you will be able to tie it. Take the strip and go
under the chair seat and up the front of the old wooden chair pulling the
strip tight and tie it at the top. This will insure they remain tight until
the glue dries. This will also hold the back down to the seat until all is
dried.
One purpose of the rubber strips is that they will not leave dents that you
will have to sand out.
Once more you have the beautiful comfy old wooden chairs that you just
repaired.