Stem form advice

[Brian J Knudsen]

Hello,

I plan to build a stem form to bend a new stem for a 1923 Otca. I have a 1942 Yankee and I read that the stem shape is the same. I can't tell from what I have because the Otca is broken and not the original shape. I am new to this so I'll benefit from any suggestions. My question now is, how much spring back should I anticipate in a kiln dried piece of ash or oak? How should I figure this into my form? I assume that the wood I will get will be kiln dried, but how would this change if it were air dried?

Thank you,
Brian

 

[Nick Dennis]

This is from Mike Elliotts blog
How To Make Solid Hardwood Stems for a J. H. Rushton Indian Girl Wood-Canvas Canoe
March 21, 2019
by Mike Elliott, Kettle River Canoes
email: artisan@canoeshop.ca

During the restoration of a wood-canvas canoe, it is rare to have to replace the entire stem in the canoe. However, when faced with the restoration of a canoe which is more than 100 years old, a new stem (or two) is more than likely going to be part of the project.



I restored a 1905 J.H. Rushton Indian Girl canoe. Both stems had extensive rot and one was broken in two places. Rushton made his stems from a solid piece of rock elm. Since this wood is nearly extinct now (thanks to Dutch Elm Disease), I used straight-grained ash 1″ (25mm) thick (at the lumber yard this is referred to as 4/4 ̶ pronounced four-quarters).



The first step is to remove the stems from the canoe. I use both a tack remover and a Japanese concave cutter bonsai tool to remove the fasteners without doing too much damage to the ribs, planks and stems in the canoe.



The next step is to create a bending form. Here, I present the dimensions of the bending form required for the Rushton Indian Girl.



It is comprised of three layers of 5/8″ (16mm) plywood. I ask my local building supply centre if they have any damaged sheets of plywood. I can get all of the wood I require for a fraction of the cost of full sheets of plywood. All three piece have the same curve but the centre piece of plywood has a longer base which clamps easily into a work-bench vice.



I start by placing the original stem on one piece of plywood and drawing the inside curve of the stem onto it.



I then keep the stem-top in the same location as the original while rotating the stem until the curve is about 3½” (9cm) greater than the original. The form shape is then drawn onto the plywood and is extended about 6″ (15cm) at both ends to accommodate the clamping system.

 

[Andre Cloutier]

Couple quick things: air dried, not kiln dried. Straight grain with no runout will minimize failures. Soak a week and steam an hour per inch at 200 deg. Leave on the form for a couple of weeks and spring back should be minimal. Once it’s beveled it should be easy to move. Best of luck

 

[Brian J Knudsen]

Thank you both. Good information. I will seek out air dried oak or ash to make things go more smoothly.

 

[JClearwater]

Brian,
There is a mill near me that has air dried lumber. Give me a call or email. I’ll hook you up.
Jim