Midnight Woodworking

Woodworking

Steam bending kit

I purchased a steam bending kit from Rockler and it arrived this weekend. I have a piece that I want to bend up for the Sitar that I am building, so I figured I would try building my own steam box.

Rockler steam bending kit

Rockler steam bending kit

The kit from Rockler came with the steamer, the hose, plans, and hardware.

Extras that I bought

Extras that I bought

Additionally I picked up some hose for a drain line, weather stripping, a dowel, screws, and a meat thermometer. My plan is to mount the whole thing to one of my saw horses, so the box will be tailored to fit on it.

My trusty saw horse

My trusty saw horse

The plans for the steam box are a little vague, but that is because you need to size it to your project. I am making mine longer than I need because I hope to use it again. You can use kiln dried solid wood, or plywood. Since I have some left-over 3/4″ plywood, that is what I am going to use.

Cutting the plywood to length

Cutting the plywood to length

I cut a couple of boards to 3′ in length, then ripped two boards, 6″ wide and two others, 3″ wide.

Ripping the plywood to width

Ripping the plywood to width

 

Laying out the dowel holes

Laying out the dowel holes

I laid out centers for 3/4″ holes every 4″. I drilled them about 1/4″ deep.

Drilling every 4"

Drilling every 4″

 

Cutting the dowels to length

Cutting the dowels to length

I cut some 3/4″ dowels to 3-1/2″ long, and inserted them into the holes. They will support the wood strips, that I intend to steam.

Dry-fit successful

Dry-fit successful

When everything was lined up, I added the top and bottom and clamped it all tightly together, then inserted screws every 6″ or so.

Screwing the box together

Screwing the box together

After the sides were screwed together, I cut two end caps.

The end caps

The end caps

 

Adding some weather stripping

Adding some weather stripping

I attached weather stripping to the door side. I used a closed cell EDPM strip instead of the foam type of weather stripping. I figured the foam would act like a sponge.

Attaching the hinges

Attaching the hinges

I screwed on the door hinges, trying to hold the door tightly closed. I then flipped the box and attached the latch to the other side of the door.

Attaching the latch

Attaching the latch

 

A hole for the thermometer

A hole for the thermometer

I drilled a hole in the top for the thermometer, and one in the bottom of the door, for a steam vent.

Vent hole in the door

Vent hole in the door

 

Drain hole in the bottom

Drain hole in the bottom

I drilled a 1/2″ hole in the bottom at the opposite end for my drain hose. I also drilled one in the center of the rear end cap.

Hole in the rear panel for the connector

Hole in the rear panel for the connector

 

Attaching the connector

Attaching the connector

I attached the supplied coupling to the panel, then screwed on the panel.

Drain hose attached

Drain hose attached

I laid out two legs on a scrap piece of wood. I made the front leg 1″ taller than the rear.

Laying out the legs

Laying out the legs

I cut a 5-1/2″ wide notch in the bottom of each leg, to straddle the 2″x6″ on top of the saw horse.

Cutting the bottom notch

Cutting the bottom notch

 

Counter-sinking the attachment plates

Counter-sinking the attachment plates

To mount the legs, I made a top plate out of some scrap oak and pre-drilled the mounting holes. I then attached them to the legs.

Attaching the plates to the legs

Attaching the plates to the legs

I attached the legs to the bottom of the box, placing the taller of the two near the door end so the condensation will drain to the back end where the drain hole is.

Mounting the legs

Mounting the legs

 

Adding another rail to the saw horse

Adding another rail to the saw horse

I added a scrap piece of pine to the other side of the saw horse to support a sheet of plywood. I placed the steamer on the plywood and the steam box above, as well as a bucket for drainage.

Set up and ready to test

Set up and ready to test

 

End view

End view

 

Cutting a strip of walnut

Cutting a strip of walnut

With the box assembled, I cut the strip of walnut that I want to bend up.

The part that I am matching

The part that I am matching

The sitar has a bent aluminum bar that acts as a leg rest. I used this piece to lay out the new one.

Tracing the ends

Tracing the ends

I traced the old part, then cut it out on my band saw.

Cutting the radius'

Cutting the radius’

Once sanded, it looked pretty good. I did not drill the holes first because I didn’t want to introduce any additional weak spots for bending. They can be drilled later.

Cut and sanded

Cut and sanded

 

Loaded into the steamer

Loaded into the steamer

I fired up the steam box while I was making the crook piece. By the time that I was ready to load it in the box, It was steaming really well. the temperature in the box was around 160 degrees.

The drain works well

The drain works well

 

Laying out the bending form

Laying out the bending form

I left that to cook a while and went back into the shop to make the bending form. I laid out an arc that had a smaller radius than the original crook. I understand that you have to over-bend when steaming the wood because it will bounce back a bit when it is pulled from the form.

Doubling up the thickness

Doubling up the thickness

I screwed two pieces of plywood together to get a thick enough form, then cut it out on the band saw.

Doubling up the thickness

Doubling up the thickness

I screwed this piece to a scrap plate and went to get my strip of wood.

Ready for bending

Ready for bending

 

Steamed for 1 hour

Steamed for 1 hour

It steamed for about an hour, but when I tried to clamp it to the form, it started cracking almost immediately. This means that it didn’t cook for long enough.

Epic fail!

Epic fail!

I decided to make two more pieces and steam them for twice as long. That way, if I screw up again, I can just throw the other one back in and keep cooking it.

Made two more and steamed them longer

Made two more and steamed them longer

Two hours later, I tried again with much more success.

One worked well

One worked well

I decided to clamp both of the pieces to the form since I made two. Also, the second piece will have a slightly larger radius, in case I miscalculated the spring-back.

Why not clamp them both up?

Why not clamp them both up?

Since I have the wood stove going, I placed the form on the hearth. I will leave it there for a day or so to make sure it dries out thoroughly.

Drying by the fire

Drying by the fire

My steam box seems to have swollen and delaminated a fair bit. The weather stripping shrunk up more than I expected as well. I suspect that I will build the next one out of solid wood to try to avoid this and maybe be able to re-use it again.

My box bent more than my walnut...

My box bent more than my walnut…

 

2 comments on “Steam bending kit

  1. Mike
    January 19, 2015

    I didn’t see any mention about sealing the plywood itself, and that is why the box itself warped. I can only guess how much moisture must be in that plywood after hours of steam.

    Do you think adding a second steam hose at the other end will help with any longer parts that you may do in the future?

    Best of luck.

  2. Lwroten
    January 19, 2015

    I didn’t bother sealing the box because I really wanted to see how the plywood would react. The box was made with very inexpensive plywood and the glue just separated. The door was made from some expensive white oak ply scraps and it held up great. Before I try a second steam line, I will probably add another thermometer at the other end to see if there is any temperature difference. The kit I bought doesn’t have anywhere to hook a second line anyway.

    This box was mainly an experiment to learn from. I have a friend who has done a lot more steam bending and he strongly recommends using galvanized pipe. He said that everything else he has tried has failed to some extent.

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