Steam Bending

[Scoony]

Got the last crest in the bending form tonight so I figured that I would show my simple stream box set up. 

The box is built from 4 pieces of big box store 3/4 x 6 x 6' pine, with some scrap for the ends. The steam will try and cause the box to tear it self apart. When I first made it, I used cut nails. Cut nails do not have the holding power claimed. When I pulled it out of the shed for the set of chairs, I had to pul it apart and use screws to reassemble. 

The steamer is less then $50 from BORG. It is actually for removing wall paper, but it does great for a steam box and about $10 cheaper then what the woodworking stores offer.  

A bucket at the end catches water, and you need to prop the opposite end up to get the water to run out one end. The newspaper keeps the steam in the box. Probably something better to use, but I have lots of newspaper and it works. 

 [attachment=9574]

I did not use the steam box here, it was moved outside the garage door on top of a garbage can. 

[attachment=9575]

Ok, so I am using a air compressor fitting shoved into and taped to another plumbing fitting. Thread actually matched the threaded hose that came with the steamer. It works!

You can see what the steam does to the box after a few uses. This box is not pretty, but it does the job.
[attachment=9576]

After 1 1/2 hours, the red oak is ready to bend
[attachment=9577]

[jteneyck]

Thanks Scoony.  How much spring back do you get from something like that and do you plan for it by over bending?

John

[Scoony]

Thanks Scoony.  How much spring back do you get from something like that and do you plan for it by over bending?

John

I haven't measured it, but haven't really noticed much spring back. Of course, the longer it is left in the form, the less spring back. I will measure this last crest before removing it and after to see.

[Scoony]

This shows the amount of spring back.  The top crest was the last one bent. The one below in the form is the last crest for this set of chairs.  You can see how much the one out of the form sprung back. 

     

The end results match the back of the chairs. The ends that didn't get bent in the form get cut off to shorten the crest.

Also the Wagner steamer I have is only one gallon. The ones sold through woodworking supplies are 1 1/2 gal. This steamed for 1 1/2 hours and still had just under half a gallon at the end. Plenty big enough for steam bending jobs.

[jteneyck]

This shows the amount of spring back.  The top crest was the last one bent. The one below in the form is the last crest for this set of chairs.  You can see how much the one out of the form sprung back. 

 

The end results match the back of the chairs. The ends that didn't get bent in the form get cut off to shorten the crest.

Also the Wagner steamer I have is only one gallon. The ones sold through woodworking supplies are 1 1/2 gal. This steamed for 1 1/2 hours and still had just under half a gallon at the end. Plenty big enough for steam bending jobs.

Thanks Scoony.  That looks like a lot of spring back unless I'm not seeing it right.  It looks consistent with what I always had when I tried steam bending.  Not being able to control it was incredibly frustrating to me, and I moved to glued up laminations.  

John

[Scoony]

Thanks Scoony.  That looks like a lot of spring back unless I'm not seeing it right.  It looks consistent with what I always had when I tried steam bending.  Not being able to control it was incredibly frustrating to me, and I moved to glued up laminations.  

John

The spring back actually fits the chair.  I have seen elsewhere to make the form tighter then what you want the end results. The spring back is going to happen to some degree, so it needs to be designed into the form. I made the form from the Anarchist's design book so I am sure it was planned that way.

[TFM]

The spring back actually fits the chair.  I have seen elsewhere to make the form tighter then what you want the end results. The spring back is going to happen to some degree, so it needs to be designed into the form. I made the form from the Anarchist's design book so I am sure it was planned that way.

Another excellent post topic.  I've zero experience steam bending, but want to do some in the future.  I've read where some folks advise that once out of the steam box to bend your piece to your form with the wrong side out, then immediately flip it 180 degrees (not end over end) and bend it or clamp it as you wish.  Essentially bending the piece on both directions instead of just one.   This supposedly helps breakdown the lignin thus reducing spring back.  Any experience with this?

Tim

[Scoony]

Another excellent post topic.  I've zero experience steam bending, but want to do some in the future.  I've read where some folks advise that once out of the steam box to bend your piece to your form with the wrong side out, then immediately flip it 180 degrees (not end over end) and bend it or clamp it as you wish.  Essentially bending the piece on both directions instead of just one.   This supposedly helps breakdown the lignin thus reducing spring back.  Any experience with this?

Tim

Never heard that before. You have to work fast with the wood, so I would think that bending it the wrong way first would eat up a lot of time. You basically have to go straight from the steam box, right to the form and start bending right away. Soaking them in a hot water bath may be different.

It is amazing how strong thin pieces of wood can be when they are rived along the grain. I wonder if bending both ways could actually weaken the wood.

[handi]

Nice! 

I built my box about the same size, out of regular ply. Has worked great for five years now. I made a hinged door with weather seal and a latch. Box has no issue holding steam. 

I use the Rockler steam generator, basically the same unit as yours. Runs about 90 minutes of steam.

[Herebrooks]

Pete Galbert (chairnotes blog) has begun putting a piece of 3 or 4 inch pvc inside his steambox to contain the steam better and save the box. Essentially the box becomes a support for the pvc.