Friday, June 12, 2015

Chair Build Days 4 and 5

Much has taken place in the shop since the last post two days ago.  Yesterday, I pulled another piece from the water and was quite pleased to see a 39% MC reading.  This meant it was time to steam and bend.

After soaking for about two and a half days.

First I had to do a little adaptation to my steam delivery system.  Up until yesterday I had used the 12' hose connecting to special fittings on both the steamer and steam box.  The problem is 12' of hose is 9' too much.  In the past I was unable to get my steambox up to 212 degrees, and I believe it was because of a heat loss in the hose.

Wallpaper steamer requires the fitting on the hose.

Hose fitting to connect the hose to the wallpaper steamer.
 After lopping of 9' of hose I was left with 3' of useable hose with a fitting on one end and open hose on the other.  What I discovered was a 3/8" ID hose inside of the black exterior hose.

Black hose acts as an insulator around the white hose that carries the steam.

 Next I removed the brass fitting from the steam box and on the drill press bore a 7/8" hole that provided a tight fit for the black exterior hose.

Brass fitting was required when using the hose as it came from the manufacturer.
While the steamer was bringing the temperature up in the box, I carved a piece into a 7/8" round bow. I marked the center with a line and an arrow so that I would know what side to put up.  It is best to figure this out before you have a very hot piece of wood in your hands that needs bent in 45 seconds. I mark the wood in such a way that the tangential plane is against the form.  The tangential plane is parallel to the bark and the radial plane runs from the pith to the bark.  This would mean the growth rings would be parallel to the bending form.  I am happy to report that my steam box made it to 212 degrees with ease.

The steam box actually held 212 degrees without a problem
The bow was in the box and the timer set for 1 hour.  When working with green wood I will usually steam pieces for 30 minutes.  Since I was working with wood that had been air-dried I rehydrated the pieces and doubled the steaming time, as suggested by Pete in his book Chairmaker's Notebook. While the steaming was taking place I prepared for the bending.  As I said before, once the piece comes out of the box you have a short bit of time to wedge the piece at its center point (arrow up facing the form), bend, pin and wedge the the ends before it cools too much.  When the hour was up I put the bow in the form and bent away.  I was so so happy with the results. It bent like I had just taken the piece out of a freshly cut tree.

The only place where a fiber or two raised , SUCCESS!
I attribute the success of the bend to being able to rehydrate the material and being able to deliver a consistent flow of 212 degree steam through out the steam box while using a defect free piece of oak. I was so psyched with the results I carved two more bows and put them into the steam box for an hour.  Well it would be great if I reported only my successes, but that isn't me.

The other two bows came from pieces whose grain was not as straight as it should be (understatement of the week) and as a result I ended up with a few small delaminations.  I was able to use some polyurethane glue and tape to repair those.  This morning I steamed and bent two arms that I carved and they were out of some wood that I most likely should have cut short of the wonky grain and used for spindles.  However I had to give it a go (I need help). One of the arms suffered major delaminations and required glue, clamps and then tape.  At this point this arm has become an experiment.  The other arm fared a bit better but I will most likely burn it also.  It is said that a picture is worth a thousand words, well here you go.

Delamination in the bow caused a kink most likely rendering it unusable.  There is some extra material on the bow, therefore if I am able to fare the curve without loosing to much material it will be used.

This is the repaired delamination that caused the kink.

This arm bent the best but the wonky grained prevented me from being able to keep it flat in the form.  As part of my experimentation I have clamped it to my bench top with holdfasts to see if it will set in a flatter profile.

Moral of the post: If you find yourself wanting to bend pieces like these DON'T!  Seek help!
Five bends with one for sure usable bow and four ahhh maybe's.  I guess we will see how or if I am able to recover.
When the day ends it is time for the clean up crew.  My grandson Zane telling me "I help Pappy".

I have an arm that I had bent earlier so I am good to go there.  I usually bend more than one component just in case, and it appears it was a good thing.  Next I will be carving the spindles and then setting them aside to dry with the bendings from this past session.  Until the next time may you be blessed with straight grain always.

~ Ray Schwanenberger

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