Steam bending in a tiny way!

[Gene O. Carpenter]

I need a little advice on my 1st attempt at bending with steam.. I have an 8" Astronomical Telescope that I want to make a Sun filter in order to look directly at the Sun.
The filter material is a thin Mylar with a special coating.
The strips will be Oak milled out to 3/8"X 1" and 1/4"X 3/4".
I am going to make the hoops at a 7" bend so when the have cooled and dried the diameter will be between 7" & 8". That way when I make my half lap joints stretch them into position the tendency will be to spring inward instead of outward. This I presume will be easier to control while securing this tiny joint for glue curing time..

This sure is different than Dan's thread on steaming those planks for the USS Constitution!

Anyway I'm going to use a 16 qt pressure cooker for my steam source, will run copper tubing to a piece of PVC that's 4"Dia X 4' long. The top will just have a piece of Aluminum foil banded on to hold it in place. The bottom end will be a slip cap with a 1" hole in center.
When the steam starts to enter this "steaming chamber" how long do I steam the strips? Should they be suspended so there's no contact with anything? Do I presoak them overnight in any type of solution?
I planned on tying a long piece of twine to each end, wrapping the strips around a form and pulling it tight and securing til they've dried sufficiently enough to handle for cutting to size and half lapping..
Thank you...
Gene

[Bruce Wrenn]

Take a look at Michael Fortune's article on Free Form Steam Bending in the Sept- Oct issue of FWW. You could take a large pot and make a plywood lid to fit over it. Cut hole in the middle to allow for four inch pipe to fit vertically over it. Use floor flange and screw to plywood. Put a piece of hardware cloth over hole to prevent strips from falling into pan. Steam away.

[Don Abele]

Gene, steam bending is steam bending whether it's our oak hull planks or your telescope ring. Your rig sounds like it will work. We do not presoak (that would be a BIG tub and steam for 1 hour per inch of thickness. The time starts when steam starts to exit the unit.

We have steamed more than one piece at a time. We have an insert that holds the wood vertically inside the unit so steam flows freely through and all around all the pieces.

Hope this helps, best of luck, and let us know how it turns out.

Be well,

Doc

PS: Be careful, surface temp on the wood will be about 200 degrees!!!

[Bob Smalser]

The strips will be Oak milled out to 3/8"X 1" and 1/4"X 3/4".
I am going to make the hoops at a 7" bend so when the have cooled and dried the diameter will be between 7" & 8".

Anyway I'm going to use a 16 qt pressure cooker for my steam source, will run copper tubing to a piece of PVC that's 4"Dia X 4' long. The top will just have a piece of Aluminum foil banded on to hold it in place. The bottom end will be a slip cap with a 1" hole in center.
When the steam starts to enter this "steaming chamber" how long do I steam the strips? Should they be suspended so there's no contact with anything? Do I presoak them overnight in any type of solution?

The biggest factor involved by far is grain runout. Insure your bending stock has been dimensioned so it contains zero.



The chalk line marks where I'll rip this stock on the BS before jointing and dimensioning to insure the grain is dead parallel to the board edges. I'll repeat the same to align the face grain if it also contains runout.

The next biggest is moisture content. If your stock is kilned cabinet wood @7% MC, then mill twice as many pieces as you need because you can expect a high percentage of failures. Airdried or fully acclimated to the outdoors @12-18% MC is much better for bending. You can even scrounge some green firewood from a local supplier and split out your own bending stock that would be far superior to storebought kilned stock.

No oak will bend to less than a 12" radius without a steel backing strap, so in addition to a form, you'll have to make one. With light stock like yours, thin steel flashing as used in roofing with a hook riveted to the lower end will work fine.

Add some crosspieces to the bottom of your steam chamber to keep your stock out of the condensation running along the bottom. And 3/8" thick oak should take 20-30 minutes after the steam begins to exit from the top of your pipe.

[Ted Calver]

I recall seeing lots of wooden hoops at the Michaels store for needle point. Would one of them work??

[Doug Shepard]

You might want to investigate using a silicon rubber heat blanket or a hot iron like luthiers use for making the extremely tight radius bends for the lower neck access cutaways on guitars, mandolins, etc. On something as tight as the 3.5-4" radius of yours, you might get less springback. Just one thought.

[Gene O. Carpenter]

First I would like to thank Bruce, Don, Bob, Ted & Doug for answering my plea. Last night I wrote up a reply and wanted to check something out before I posted it and without thinking, had been a long and trying day, I hit Google and the instant I hit it I thought "you idiot you didn't copy it first,,it's gone"! And it was! So going to try again this AM.
I don't have to use Oak for this little project! Only selected this species because I like the smell and it's appearance and was the easiest board to dig out of my wood pile.
If there is a better suited species that would be easier for my 1st attempt at steam bending then I will look thru the pile again.
The plank that it would have been sawn off of was bought by me back in 91-92, along with 16 others, as a 5/4"x8"x12' RS plank. They have been stacked and stickered in my cellar since then. It was meant for a project that never got got started, but I did run it thru my home built planer(see photo) to save the blades on my bench top Delta.

Don, What was the purpose of "your" high hat? What with the low head room below deck I would think that it would be quite hinder-some! In my two (2) weeks before the mast of the USS Roberts DE 749 on a two (2) weeks wonder cruise to Nova Scotia during the Summer of 1954 (15 yrs before your birth), I banged my beaner, that reached 6' 4-1/2" off the deck, numerous times.
Couldn't figure out how to upload the photo's on this site so can't show you my home built planer!

[Don Abele]

Gene, my hat would not have been worn below decks (for VERY obvious reasons). The uniform I wear is taken from a painting of the Sail Master in 1812. Uniforms for officers and the like were meant to make us look gentlemanly. Even in the oppressive heat of the summer we wear those woolen coats. The "working hands" would have worn uniforms more utilitarian in nauture.

Thanks for checking the site out.

Be well,

Doc

[Gene O. Carpenter]

Don,
My youngest son David and his girl friend went on the tour about a month ago and he said it was awesome! I've seen the Tall ships from Mt. Mitchell as they sailed into NY Harbor for our Bicentennial and they are something to behold! BUT after riding out Carol on a 300 some foot tin can and getting as sick as I did, I wouldn't want to ride out any storm aboard any one of them! That's why I jumped ship and enlisted in the Army. Spent 1 year working at Signal Labs at Ft Monmouth NJ and 2 years at a NATO Radio Receiver Site in Izmir Turkey.
I sure would like to watch you swabbies seat one of those crooked planks on that old Gal, would be one hell of an experience just watching.
Take care and watch your noggin when you're below deck...
Gene

[Don Abele]

Gene, they actually installed the beam today (I wasn't there). I'll have to check with my Public Affairs guys and see if they took any photos. I know it involved a crane, a forklift, and 9 guys to get it into place. Once in place it's installed using the methods I showed in the thread about removing/installing hull planks. Mad that I missed it going in. Oh well, we have a few more that have to installed, I'll get some shots of them and post.

Be well,

Doc

[Tim Marks]

If your 7" radius is too tight to steam bend the circle, then how about just ripping some 1/8" strips and laminating the ring? This would probably be simpler, the resuts will be much stronger, and quite probably even more beautiful?

[Cliff Rohrabacher]

No presoaking~!! The steam does not do the loosening of the Lignum. It is the heat that does it. The steam carries the heat deep into the wood. A presoak will simply make it impossible to work or glue the wood till after it all dried out. Steam wets it but does not soak it, so it dries faster.

Yes you should suspend the wood strips on something. Some guys drill little holes in their boxes through which they shove little dowels and on those dowels they set their wood.

Some folks also bend the wood in Both directions before clamping it into the form to make it yet still more loose and flexible.

Don't bother with trying household Ammonia. The ammonia in it flashes off almost instantly leaving you with nothing but stinky water. Ammonia bending is great but, it requires anhydrous ammonia and your box must be a welded up pressure vessle because the stuff flashes off at 26-Deg-F (yah below freezing) and is highly flammable and lethal to breath.