Cherry outwales failure during steam bending

[Douglas Kestell]

I tried to steam bend new cherry outwales for a 1915 OT Charles River I am restoring. I soaked the last 4’ of of the outwales for a week and steamed them for about an hour. The dimensions are ~1” square. It’s the same stock I made my inwales with but every piece cracked.

Unlike the inwales that are square in cross section, I tried to bend these with the profile to accept the canvas and planking already.

Was that my critical error- citing the profile before bending?

I’m considering bending them as square stock and only bending the upswept ends so I can mill out the inner profile on my shaper after they’ve dried.

I’m concerned they’ll fail when I install them and bend them around the hull.

Or is laminating outwales a legitimate option?

Thoughts / insights?

 

[Rob Stevens]

This failure may have been to using kiln-dried stock.
Grain run-out may also have been a factor.

 

[Nick Dennis]

As Rob says you may have KD timber rather than air dried. When I did the outwales for my 1911 I cut the profile first, steamed for an hour for the whole length of the canoe working along from the centreline clamping and screwing as I went using the polythene bag/tube method. Who i got the the ends with the taper, the first went beautifully, the second folded and created, the third had a minor crack whilst the last wanted to twist. They all came from the same piece of mahogany with the grain all running in the same direction. Thats wood for you.

Try, try and try again. May be worth experimenting first.

Nick

 

[Todd F]

Nick, could you share any photos of your poly bag / tube steaming system? Thanks in advance.

 

[Nick Dennis]

Here you go Todd. Look at the photos in post No 35. We use polythene tubing which they use for plastic bags. Stuff one end with a rag, stick a wall paper steamer in the other end again with a rag and a clamp and then work along the wood from centre to stems.

Nick
http://forums.wcha.org/index.php?threads/1911-aa-old-town-charles-river.17254/page-2

 

[Todd F]

Thanks Nick, that whole series of pictures is very helpful!

 

[Douglas Kestell]

Thanks for the insights. The wood is air dried- I get it from a local sawyer, but the wood has sat in a steel pole shed for ages.

With that said, on my last canoe, I bent the ends and worked towards the middle, cut the 10:1 scarf, glued and completed the assembly.
I’m thinking to instead, to cut the scarf and glue, and work from the middle out towards the ends instead using the poly tube methods, and just work it slowly as I go.
Worse case, the sawyer still had a bunch of cherry and the price is right ($20 USD for a 5/4”x8”x10’ board). It seems worth my while to experiment and gain the skill of doing this the right way.

Thanks again for the help

 

[samb]

The poly tube is also great for soaking your wood for a week before steaming: Cut a length, tie a knot in one end, put the wood in, fill with water and stand it in the corner for a week. If you want to stay completely dry, reverse the last two.

Sam

 

[Rob Stevens]

Thanks for the insights. The wood is air dried- I get it from a local sawyer, but the wood has sat in a steel pole shed for ages. "

I have worked a lot with black cherry, most often for paddle carving. Some cherry seems to be almost punky, seemingly "rotting" after having sitting unused for a long time. Even worse if it was exposed to the weather. It may be that the tree was sick or standing dead before being felled.
I can often catch it when ripping. It just seems softer than usual, and there's a weird micro-banded pattern (not like curly) in the grain. I have learned to chuck that stock, or at least not use it for anything that requires structural strength.

 

[Rod Tait (Orca Boats)]

My experience is that if there is a slight circular grain in the wood it may blow apart and sometimes these are hard to even detect. If steaming the whole piece, your scarf joint may come apart.

 

[samb]

My usual practice is to cut the rebate and taper, but not round off the edges, then clamp the outwale for about 4 feet either side of the centre then to put poly tube over each end - so on a 16' boat the final 5 feet or so. ( I always give a fair bit of extra length so I've got something to pull on). Only steaming the ends where the main bend is means I keep well clear of the scarf.
I've never done cherry gunnels, only ash, so that might not work for you,
Sam

 

[Dave Wermuth]

I use camper sewer hose in lieu of poly bag. Flexible and the 4" diameter is maintained with the coil of wire and gives good volume of steam.

 

[Greg Nolan]

There is some information on steam bending in a poly tube here:
http://forums.wcha.org/showthread.php?12999-STEAM-BENDING-IN-A-POLYETHYLENE-TUBE-part-1

 

[chris pearson]

Unless there is no runout and rings are horizontal when you bent it, I agree that cherry can break pretty easily. A lot of it has crazy grain, so choice in the stock is paramount.

 

[Andre Cloutier]

FWIW, you may be oversteaming. Ive done lots of rails with strong upsweeps, and i really soak them for days before as well. Oversteaming will dry them out as im sure you know, so its a bit of a balance but for rail profile i have found between 20-30 minutes of 200deg steam is lots. Good luck!

 

[Douglas Kestell]

Thank you all for the advice.

I am happy to report I had success today utilizing the steam in bag method.

I soaked the outwale for 3 days in a 4’ section or 4” pvc and used a length of the vacuum seal bag material as the steam chamber.

It worked much better than I was anticipating and will be using this method going forward.

I will bend these prior to canvas and filler next time. I had anticipated that using a profile form would work without a hitch and proceeded with canvas and filler to allow dry time while were away during the Christmas holiday.
Thanks again

Cheers