Bending Cedar for Arch

[Azryael]

Hi all,

New to the forums, and just about intermediate with my woodworking skills.

I'm trying to build a door frame out of cedar, for which I'll be making a set of double doors out of cedar as well.

The issue I've run into is that where I intend to put the doors, I have an arch I have to incorporate into my door frame.

I've tried kerf cutting and soaking (what I assume is not kiln dried cedar) my arch piece (thickness planed down to 5/8") and letting it set in a jig built using 2x4 posts affixed to plywood resulting in warpage or cracking.

Is building a steam box the best way to do this? I've soaked each piece in hot water for several hours before bending, as I lack the space for building a steam box currently.

What are my other options for completing this arch? I want to retain the natural cedar grain, as I will be eventually replacing all of my baseboards and door frames with cedar in the near future.

I've calculated that where the arch meets the side pieces, each joining end must have a 17.5° angle cut to fit together perfectly.

Here is the arch in question:



Thank you!

[FS7]

I wouldn't bend anything. When I built the arbor for my wedding, I had incorporated an arch in that (very similar size and curvature, actually), and I cut the curve on the bandsaw from a 2x12. What I would do is the same - glue up the appropriate amount of cedar (be careful, cedar doesn't glue that well unless it's really dry) and cut it out on the bandsaw. It creates a lot more waste for sure, but you might be able to repurpose what you cut out. I still have my piece.

The downside is that the grain won't "flow" around the arch. You can try gluing up different pieces to have a more natural grain, but then you have the joints. It's also more work.

[Cooler]

I've done this with oak, I'm not sure about cedar.

I cut strips about 1/8" thick which was flexible enough to take the  bend.  Then I glued up over a form several layers until I got the thickness I required.  Outdoors you will need a water-proof glue like Woodworkers III.  

This will be face grain against face grain.  On oak it made a very strong bond.  I'm not sure about cedar, but it is a lot of surface and should get a good bond.

This article says that Titebond will work on cedar:

http://www.woodworkersjournal.com/big-pa...-biscuits/

[Azryael]

Thanks, guys.

I figured laminating pieces together was probably going to be the most likely way. At the same time, I don't mind if there are joints that can be seen if I cut the pieces in a fashion as to preserve the natural grain.

I've already used Titebond WWIII on another Cedar project and it's worked wonderfully.

Does oak lend itself better to bending? If I choose to stain these pieces, I could probably get the oak to match the cedar in color.

Red oak might have a closer match with its reddish color, but that might also be harder to bend.

[Cooler]

Thanks, guys.

I figured laminating pieces together was probably going to be the most likely way. At the same time, I don't mind if there are joints that can be seen if I cut the pieces in a fashion as to preserve the natural grain.

I've already used Titebond WWIII on another Cedar project and it's worked wonderfully.

Does oak lend itself better to bending? If I choose to stain these pieces, I could probably get the oak to match the cedar in color.

Red oak might have a closer match with its reddish color, but that might also be harder to bend.

I don't know if it is harder or easier. I do know that I had to slice it pretty thin to do so.  How are you planning on making the cuts?  the narrow stuff will kick up as well as back, so you have to be careful.  

If you mount a sacrificial fence only just up to the first 1/3 of the blade it will mitigate that issue. 

If you have an in-feed and an out-feed stand you can cut on the other side of the blade safely.  But these are going to be pretty long pieces so it might prove difficult.  Here is how it is done.  It is a very safe way to make narrow slices:

[Azryael]

Hmm, I was still going to try the one-piece bending method with oak, first. The use of kerf cuts will reduce the rigidity and aid in bending.

I actually was able to successfully round my first piece of cedar, with Kerfs, but I ultimately cut it too short, and it developed a slight warp.

[jteneyck]

A bent lamination will be stronger and look better than one made of solid wood.  You can bend most any wood once it's sliced into thin strips.  1/8" would be fine for the arch you have.  All you need is a simple form like this to bend the plies around.
 




This is within your skill set if you are an intermediate. 

John

[Azryael]

John, that's great!

Did you steam the wood?

[Cooler]

I bent the oak without steaming.  

Keep in mind that if the arc is not constrained it will open some.  So you probably want to make the form a tighter arc than the doorway.  Since it will be constrained by the arc of the doorway it should not be much of a problem horsing it into position even if the arc is not exactly accurate.

Again, be careful cutting narrow strips.  I was careful about kick back but the strip kicked UP and tore of the fingernail on my pointer finger.  It was painful and took 8 months for the nail to grow back.  I had to go to the emergency room to get the nail trimmed off.  And blood everywhere.  

A very minor accident in the shop but it makes me wary of cutting narrow strips.

[Azryael]

When it comes to the narrow strips, I'll probably just plane them down.

I'll use more wood, but it ends up being a bit safer. I know my table saw will not cut higher than about 4". This frame is set to be 5 1/4" wide.