How to bend wood like this - Outdoor furniture project

[Jim Becker]

I would use epoxy resin both for the long working time and the bond. West Systems, Total Boat, etc.

[Michael Burnside]

I agree with Jim. However when you say "I was thinking that the high clamping pressure might make epoxy a great choice, but may be mistaken there for this application.", remember that epoxy doesn't need a lot of clamp pressure to work. In fact, too much and it is not a good idea. Epoxy has gap filling properties which may help you here on minor variances.

[Alan Lightstone]

I agree with Jim. However when you say "I was thinking that the high clamping pressure might make epoxy a great choice, but may be mistaken there for this application.", remember that epoxy doesn't need a lot of clamp pressure to work. In fact, too much and it is not a good idea. Epoxy has gap filling properties which may help you here on minor variances.

Whoops. I typed that backwards. What I meant to say was that I was worried that high clamping pressure would make epoxy a POOR choice. I corrected it above.

[Mike King]

For a really rigid glue line, I'd use Unbound 800. It is ok in exterior applications as long as it isn't continually exposed to water.

[Maurice Mcmurry]

I use West System epoxy thickened to paste consistency with collodial silica. It wets out amazingly well without running all over the place. The exceptional wet out characteristics insure that it will stick strong whether its quite thick or very thin.

[Alan Lightstone]

I use West System epoxy thickened to paste consistency with collodial silica. It wets out amazingly well without running all over the place. The exceptional wet out characteristics insure that it will stick strong whether its quite thick or very thin.

I tried that route yesterday with a couple of layers. Going to take off the clamps today (48 hrs). I'll then see how much springback (if any) I get from the first two inside layers. Strengthwise, I don't think I would be able to glue all 10 laminates together and then bend on the form. So my game plan is to do 2-3 layers at a time, perhaps up to about 4 layers, then winch in place and place clamps.

I also bought some West Systems extra slow hardener to get really long working time.

[Alan Lightstone]

OK. That's it. Waving the white flag. This just isn't working for me. With my setup, physical strength, etc... Steam bending or bent laminations are out for this chair. The pieces have springback, gaps between lamination, uneven height. Just not at all usable and a tremendous waste of wood. Was a somewhat interesting, but mostly frustrating exercise. Spent a good deal of money on winch/straps/mdf/ etc... And have taken up most of my workshop with jigs, etc... for this. Anyone need 2 steam generators and an extra long steam box (sigh...)

So I still need to make the chair (we've already bought the expensive cushions and really need replacement chairs out there. Building them like the originals (solid wood, but not using teak) is the new plan. A whole new set of questions pops up then.

To refresh everyone who's been so helpful memories, this is what the chair needs to look like:
Chair with Seams 1.jpg

The most difficult part is the chair back, which is 5-1/2" tall and 1-1/2" thick. I can easily make a pattern of the shape and rough cut it on my bandsaw. But how do I smooth out the profile with a router table when it's that tall? Are there pattern bits that long that can safely be used on a router? No shaper here. I need to make 4 chairs, so will need to make a bunch of identical pieces. And my initial concern about lining up the pieces for gluing still seems difficult (but not impossible.)

So mostly concerns about routing the pieces identically and smoothly. Both the inside and outside curves.

[Kevin Jenness]

Forget pattern routing. Do the joinery and assembly, then saw the parts out as accurately as possible and clean up the faces. In my shop I would use an edge sander.

[Mike King]

I realize you are frustrated, but the best approach to achieve that shape is bent lamination. If you really want to get it to work, it seems like you need some expert instruction. Here's the solution to that:

https://schoolofwoodwork.com/event/2...gnfabrication/

Kelly Parker interned with Michael Fortune and teaches woodworking with him quite frequently. If you were to sign up for that class and take your project there, Kelly can help you figure out the caul, padding, and clamping that will allow you to complete your project.

Mike

[Mike King]

An alternate way to achieve the curve would be to Cooper the bend. But rather than grain following the curve, the grain would be vertical (I don't think it would be a good idea to glue end grain to end grain, especially outdoors). You would have a fair amount of hand work to fair the curves.

This brings up a design question: what is the radius of the curve for your chair back? Have you built a prototype to test the comfort of your design? Generally speaking, a comfortable radius on a seat back is 18+ inches.

[Michael Burnside]

One thought I had was what about building them in layers of say 1 to 1-1/2" tall and stacking them. You could easily build a template, rough cut on the bandsaw and flush trim, then stack them until you reached the final height. I guess after that you could veneer and hide the layering or simply lean into it, which is what I would do.

I personally applaud you for your efforts as I would have waived the flag ages ago. I'm a serious hobbyist and once all the fun is gone and it becomes a job, I've done something wrong...

[Alan Lightstone]

One thought I had was what about building them in layers of say 1 to 1-1/2" tall and stacking them. You could easily build a template, rough cut on the bandsaw and flush trim, then stack them until you reached the final height. I guess after that you could veneer and hide the layering or simply lean into it, which is what I would do.

I personally applaud you for your efforts as I would have waived the flag ages ago. I'm a serious hobbyist and once all the fun is gone and it becomes a job, I've done something wrong...

Probably my approach. I can probably find a long-enough pattern bit to do this in two 2-3/4" tall layers.

Of course that still leaves the problem of gluing those curves together (dominos I would think), and repeatability.

[Alan Lightstone]

An alternate way to achieve the curve would be to Cooper the bend. But rather than grain following the curve, the grain would be vertical (I don't think it would be a good idea to glue end grain to end grain, especially outdoors). You would have a fair amount of hand work to fair the curves.

This brings up a design question: what is the radius of the curve for your chair back? Have you built a prototype to test the comfort of your design? Generally speaking, a comfortable radius on a seat back is 18+ inches.

A really interesting suggestion, Mike. Out-of-the-box thinking. Don't think I'd like the look, but very interesting.