Monday, 11 March 2013

Steaming a Sapwood Backing Strip

I've been doing some work on an experimental 'Transatlantic' bow. Oregon Yew heartwood spliced belly and a continuous strip of English Yew sapwood for the back. There's no great reason for the nationality of the timbers other than what I have available.
The heartwood stave has a slight lateral bend of about 1/2" which I've steam corrected. I wouldn't normally worry about a 1/2" bend, I'd just lay the bow out straight, but I have very little wood to play with (width wise) so I'm trying to get it as straight as I can to avoid ending up with a bow as wide as a pencil.
The sapwood backing strip had a huge twist at one end which I've also steamed out.
I did the heartwood Saturday evening and got the sapwood done Sunday morning before we all went out for a Mother's day jaunt.

The twist came out quick and easy as the strip was so thin (about 1/4"). I've left the bark on, this will stay on as long as possible as some protection for the sapwood.

In the pic you can see the heartwood spliced billets in the vice and the sapwood (bark still on) being steamed.
Note the insulation to keep the heat in and the way the bench has been propped up at the far end to let the water run out into that old washing up bowl. As the steam condenses into water it delivers heat to the bow, and the resulting water can be quite cold.
Note:- There are other posts on the blog which explain the set up in more detail...

Any heat bending is about heat and time, if it's not hot enough for long enough it won't do the job. There are pros and cons to steam or dry heat, and I use both. Steam gives a good even heat over a decent area, but being less hot needs carefull setting up and can be spoiled if you have to waste time getting the wood out of the heat and clamped up. That's why I try to heat and clamp in one operation if possible. It's always worth the time and effort getting it all set up right, rather than ending up doing it twice.

I was hoping to get it prepared and glued up today, but there are flurries of fine snow and it's damn cold in the garage.
Meanwhile I've been applying the finish to the gold arrow plate longbow and signing it ready for collection.
I was chatting to Mick the blacksmith and I'm putting a grip on the bonkers bow for him as a thank you and swap for some forge/instruction time. He was rather taken by it's mad look yet crisp shooting performance.
It's nice to know it will get a good home and some shooting rather than standing glumly in the corner as a novelty.

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