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Wednesday, January 12, 2011

Bend Me, Shape Me, Any Way You Want Me (Part II)

So as I covered last time I was about to bend the wood strips for my project into a curve to match the SV-1.  The first round of bending failed.  For that I soaked the strips in hot water for about an hour.  The strips, while becoming more flexible than they were initially, did not really become flexible enough until they were fully soaked.

At that point I put them onto the form and glued them.  Unfortunately the glue would not work properly with wet strips and the resulting piece was a failure.

The next round was steam bending.

The first trick here is patience.  My little kettle here is fairly full of water (to just below the spout) so I get maximum steam time.  You have to focus on one strip at a time and not rush things.  First off I sort of steamed the whole strip by moving it back and forth through the main steam stream.  Its important to figure out where most of the stream is emanating from the spout - if you miss that you spend a lot more time making a bend.

The next step is to start putting gentle pressure on the strip to curve while you heat it.  You have to keep in mind the general shape of what you are trying to accomplish and you have to work at forming the piece to that shape.  This is a bit more tricky because you need to get most of the strip streamed (which is tough on your fingers) and because you have to keep the strip moving so that it doesn't cool too quickly.

So basically you just keep working it until, in the stream, you can bend it beyond where it will need to go on the form.  I worked each piece until it got to this point, then switched to the next pieces, then switched back to reinforce the previously pieces, and so on.

It helps to have the form ready to go so that when the strips are bent you don't have to rush to organize the form and so forth.

Once the strips are ready it was time to get them on the form.

The pieces must be fully clamped to the form.  This means that there must be continuous pressure around the full curve of the piece.  If there isn't, some parts will separate and the lamination will look bad or fail.  For this I used a motorcycle strap with a ratcheting clamp along with some wood clamps to get the parts that needed extra tightening.

Each strip gets a good coating of glue (Titebond II) on the faces that will be touching.  You can't glue just one side and expect the other to stick because the glue will not always flow evenly when you clamp things up.

Some skill is required to line up the strips, get things clamped before the glue dries, and otherwise make it work.  I screwed up a couple of tries before I got it working the way I wanted.

You have to let these dry overnight so that the glue has a chance to set.  They don't need to be on the form for more than a couple of hours.  Once I took them off I set them aside in another clamp to dry overnight.

I test fitted the first piece to make sure it matched the back of the SV-1.

On to the next step next time....

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