Advice Needed

[RonRock]

I am in process of restoring this garden bench. I am at the point that I have to decide on the type of joinery for the White Oak wood frame that I have made. The original was made out of what I assume was the cheapest lumber available. It don't seem to me that it lasted more than a year before going bad. So I like the bench and want it to hold up to the Iowa weather for some time. I was told that White Oak would be a good choice.

Sorry I got off track. But thought the wood type might be pertinent. Originally the wood frame had 2 1/2" top and bottom rails, and 2" sides. And it was mitered and had a tenon cut into the side (style) and mortace in the top and bottom. I assume that it was glued also. But that made a odd miter cut 51.4* as near as I can measure. Pretty hard to cut that angle reliably. So I have a few other choices that will be do able.

I have made my style's 2 1/2" to match the top and bottom. That makes a 45* miter, but also widens the bench by 1" no big problem with that I can simply make the bottom slats 1" longer to match. But that also moves out the side frame and will cause more stress on the screws that join the wood to the side frames and cast iron back panel. I could make my joint then rip off 1/2" on each side. That would leave my miter looking "odd" but not a big deal.

I could also make a square joint with either biscuits or dowels. I'm not sure how strong either of those would be. Of course it will be glued with exterior glue this time, so that should help. I've never had a problem with glue on interior work, never needed it for exterior work before.

Sorry long winded. Anybody have any thoughts on my "best" option?

[jteneyck]

Mortise and tenons are your friends with anything outdoors.  Epoxy or Gorilla Glue would be your best glue options or use drawboard M&T's and forego the glue.  Personally, I prefer the glue option.

[RonRock]

Mortise and tenons are your friends with anything outdoors.  Epoxy or Gorilla Glue would be your best glue options or use drawboard M&T's and forego the glue.  Personally, I prefer the glue option.

Thank You, jteneyck. I didn't even think about Gorilla Glue. Might be a good idea. What Epoxy would be considered? Never used an epoxy in woodworking.

I could do a mortise on the top and bottom with a 45* miter. Then make a tenon on the sides.

I was planning on Tigtebond Exterior glue. Mostly because I didn't even think about Gorilla glue.

Also never heard of drawboard M&T's.

Edit, After my reply I did a Google and found out about Drawboard M&T. Good in some situations, but probably overkill for this project. It's just a garden bench after all. But thanks for the eye opener. Good to keep in mind.

[jteneyck]

Why the need for 45 degree miters?  What I see in your photos suggests 90 deg M&T joints would work and look just fine.  

Just about any epoxy is good.  I like System Three's T-88.  West Systems and Total Boat also are well respected with a long, successful history.  

John

[Willyou]

White oak is a good choice. I agree with M&T joints (no miter) with epoxy glue. My only concern is the thickness (or thinness) of your rails and stiles. You don't say how thick they are, but they look pretty thin for M&Ts.
How are you going to mount the CI panels? I suggest that you do a little research to see how much the CI will expand and contract over the temperature span it will be subject to (if any. I don't know). Be sure you allow for that or your frame could be pulled/pushed apart.

[Willyou]

Deleted double post. Sorry.

[iclark]

Just to point out the obvious:
The mortise into the top rail does not need to be a through-mortise. By not going all the way through, the end grain of the vertical is not exposed to the weather.

[RonRock]

White oak is a good choice. I agree with M&T joints (no miter) with epoxy glue. My only concern is the thickness (or thinness) of your rails and stiles. You don't say how thick they are, but they look pretty thin for M&Ts.
How are you going to mount the CI panels? I suggest that you do a little research to see how much the CI will expand and contract over the temperature span it will be subject to (if any. I don't know). Be sure you allow for that or your frame could be pulled/pushed apart.

Thanks guys for the help.

My frame is 3/4" oak.

The cast iron is mounted to the oak by screws into the wood in the backside. On the outer cast iron frame there was originally threaded inserts into the wood and screws through the cast frame into the inserts. I plan to simply follow that.

My thoughts on a miter cut corner is that I could do a through cut for the mortise. If I leave the joint square I will have to figure out how to do a stopped cut for the mortise. Part of the reason I first considered biscuits. Sadly I sold my mortise cutter years ago after it sat unused for some time. I knew better at the time not to sell it, but it took up bench space and used very little.

I would much rather have that joint square than mitered, just not sure how.

[jstraw]

I’ve redone a couple of benches. With the hardware and the mounting method that the manufacture used originally, the original did not have mortise and tenon joints. I did use epoxy if needed. If you need tenons, perhaps floating tenons cut with a router would be easier.





I used some leftover ipe deck boards for these. Definitely weather resistant, but added some serious weight to the bench.

[Willyou]

3/4" thick should be plenty for good M&Ts. The photos just makes them look thinner.
You can make good stopped mortises with a router or remove most of the material using a bradpoint bit in a drill press and then clean out the rest with a chisel.
That sounds like a good mounting system for the CI. However, I stress that if the CI has any expansion/contraction within the +- 110-120 deg range it will be subject to, it could push/pull your frame apart.