Steam Bending Turnings

[John Hart]

I make trout landing nets and bend curly and birdseye maple strips up to 1/4" thick, but I soak it in HOT water, not steam. One thing I do recommend is to use something as a backer when bending wild grain because that will help lessen the cracking.

Philip...your backer tip was extremely helpful. In a few minutes...I'll show my work to address your advice. Thank you.

Your plexi may very well get softer at temperature, but if the pressure is low, I'm not sure I would worry about it.
As for whether it will work, I'd guess that it probably will, straighter grain turnings might be better, but the real high dollar custom fit shotguns are known for having stocks bent to fit the owner, so bending shaped wood is not entirely new.

Thanks David, for the reassurance on the plexiglass. That's kinda what I thought...and hoped for. The proof is in the puddin'....but at least you've given me some confidence that it'll work out ok.

I've selected some pretty straight-grained cherry for my first go-'round. Hopefully it'll work...but if not...we'll have to figure something else out.

Phillip,

A couple of questions. I have wanted to make a landing net for personal use for some time now.

What do you use for the backer you mentioned?

What do you use for a finish on your landing nets?

Thanks!

This is proof that this kind of thread can yield answers to questions that are unrelated to the project. I'm very pleased.

Don't know if this will help, but here goes:

I've bent guitar and violin sides. We soaked the violin sides and then bent on a hot form. A metal backing strap can be used, especially for the tighter center bout. I remember dad baking the pieces in a pan with water in the kitchen stove when he worked at home before he built a commercial shop. That was very curly maple.
At my brother's guitar shop, we a had an automatic bender that had been bought from another shop that went under. It used hydraulic rams to force shut a two-sided, heated aluminum form. The form was in sections so it bent the middle bout, then the ends. We bent maple, rosewood, and mahogany, and only had problems if the wood had not soaked long enough or was not warm enough. The soak water was heated.

You're making me think that a pre-soak in hot water might be useful prior to the steaming operation. I definitely want to steam it to get the heat and pressure effect....but the pre-soak might help in guaranteeing success. Your thoughts?

[John Hart]

Ok...Here are the results of Day 2:

First off...I got the steam input fitting and the drain valve installed.
Drain.JPG SteamInlet.JPG

And then decided to go ahead and turn the pitcher mouth prototype. I have a pile of cherry beams that I am using as railing posts for the deck I'm building.
CherryBeams.JPG

But I have more than enough...so I took one and cut off a turning blank.
So, here's the mouth. I gave it a tenon similar to how I would do it normally...and took it all the way to finished thickness at the rim. Then did a quick sanding. This is an end-grain turning so the grain is fairly straight coming up through the neck to the rim.
mouth1.JPG Mouth2.JPG

[Nathan Hawkes]

Interesting project... will be watching to see what happens.

Out of curiosity I went and looked up temp ratings of acrylic sheets, what I found was this for Acrylite sheet goods:

It can take temperatures from -40° F to 180° F (intermittent to 200° F)... ...The forming temp is 350° F.

The thickness of your acrylic will certainly help; more thermal mass. I'd certainly keep a close eye on things the first few times you use it.

From having bent a little acrylic, I know, or rather I don't know, anyone that bends anything over 3/8" thick. It just takes too much force, and you have to get the temp up to the point that it almost bubbles to get the bend right. At 350 it'll bend, but at 375-380 it bends easily. I don't know what the "vicat softening point" is, but the thermal deflection I understand--264psi at 210F is a huge amount of pressure, but the threads on the screws might see this amount of force if it weren't sealed. Now I'm really curious--I'm going to guess that under normal steaming conditions--e.g. not much higher than a tea kettle, it will probably be fine, unless you're steaming for more than 30-45 minutes. I think the folks at Cyro (acrylite mfrs) will give you technical advice if you need it.

[John Hart]

Keeping with Philips suggestion for a backing...I decided on a piece of hard maple....trying to match the profile of the mouth...just slightly larger.
BackingTurning.JPG

Then I drew a spout...sorta what I envisioned as what would sorta work out.
backingMarking.JPG

Then hogged it out with the dremel.
BackingDremeled.JPG

Next step was to make a press form. I used a small block of cherry...matching the mouth profile (slightly larger)...then taped it up so it could receive some epoxy.
FormTaped.JPG FormEpoxied.JPG

Now...after the epoxy cures....I'll file it down a bit to create the spout form. After that...I'm ready to steam!!!

The only thing stopping the process is that the steamer box caulking isn't cured yet. I guess the humidity is really slowing that down.

But I have to put some time into the deck today...so I guess it works out.

Thanks for all the great feedback!!

[John Hart]

I just caught Nathan and Kevin's exchange....That's pretty interesting. I think my confidence level is still high on the integrity of the box. I will keep a close eye on it...Thanks!

By the way Nathan...Yes..the plastic was free. In fact, I had two of these large sheets, but I gave one away to an amish friend who wanted to make some cutting boards for his family.

[Leo Van Der Loo]

John, I've done a bit of bending lexan strips, and had to heat them over a flame very carefully right up to where the material would start to get bubbles inside in order to make the curves, much hotter than unpressurized steam.

One other thing, when bringing IN steam there should be a opening to let OUT the excess of air/water vapor, right ??

Choosing wood that has stronger fiber bonding, like Elm would help in preventing the splitting that can/will occur depending how/where you bend/distort the wood, also you have to keep the temp up, at the water boiling temp at least, to be able to get the fibers to slide by each other, as that's the temp for the lignin to become kind of fluid.

I'm interested in what you will be able to do with your setup, I know R. Raffan did a little wood distorting on thin bowls when using the microwave to dry and to shape the rims a little, using the natural distortion that occurs to help him, but nothing else that I know of.

Coming back here once more, one other thing to remember is that yes you can distort wood, but you can not make it longer.

Anyway, like I always say,
Have fun and take care !!

[Ernie Nyvall]

That's cool how you whipped up that steamer John. I was wondering if a certain profile of the turning might lend itself to more stable/less cracking than others. Just a thought.

Those who turn hats sure do a lot of bending. I don't know how many crack, but they do bend the wood in two different directions (with and across the grain) at the same time which is the same as you are doing, and many of them don't crack. I think they only use green wood though and turn it very thin. Maybe a combination of the two ideas like using your backing jig in the steamer with a little pressure on the spout, and increase the pressure every few minutes. That maybe what you are already thinking of though.

I like your projects. They seem to always promote a lot of thinking, and that's a good thing.

[John Hart]

John, I've done a bit of bending lexan strips, and had to heat them over a flame very carefully right up to where the material would start to get bubbles inside in order to make the curves, much hotter than unpressurized steam.

One other thing, when bringing IN steam there should be a opening to let OUT the excess of air/water vapor, right ??

Choosing wood that has stronger fiber bonding, like Elm would help in preventing the splitting that can/will occur depending how/where you bend/distort the wood, also you have to keep the temp up, at the water boiling temp at least, to be able to get the fibers to slide by each other, as that's the temp for the lignin to become kind of fluid.

I'm interested in what you will be able to do with your setup, I know R. Raffan did a little wood distorting on thin bowls when using the microwave to dry and to shape the rims a little, using the natural distortion that occurs to help him, but nothing else that I know of.

Coming back here once more, one other thing to remember is that yes you can distort wood, but you can not make it longer.

Anyway, like I always say,
Have fun and take care !!

Thanks Leo...good food for thought. On the spout, I am just trying to fold it over a bit...not make it longer. It's not much of a bend...just a little. I'm hoping that I can acheive that.

Also on the relief...Yes, I intend to keep the drain valve open to allow steam to escape. I'm going to keep a close eye on the pressure. I don't want too much or the force can be quite high over a 15x15 area.

[John Hart]

That's cool how you whipped up that steamer John. I was wondering if a certain profile of the turning might lend itself to more stable/less cracking than others. Just a thought.

Those who turn hats sure do a lot of bending. I don't know how many crack, but they do bend the wood in two different directions (with and across the grain) at the same time which is the same as you are doing, and many of them don't crack. I think they only use green wood though and turn it very thin. Maybe a combination of the two ideas like using your backing jig in the steamer with a little pressure on the spout, and increase the pressure every few minutes. That maybe what you are already thinking of though.

I like your projects. They seem to always promote a lot of thinking, and that's a good thing.

Thanks Ernie....I forgot about the hats!!! I wonder if Doug Thompson could lend a thought or two.
But, yep...not going as thin as the hats, this might be a different animal.

[John Hart]

But here on day three...my caulking is still not cured

It's been in the 80's...but the humidity is 2000%. The caulk is still partially white. Can't risk it. Gonna hafta wait.

[Faust M. Ruggiero]

John,
Having spent the better part of my working life in the clothing manufacturing industry, I have lots of experience around steam. I am sure you have not built your box to become a pressure vessel. You actually want it to leak. Steam is 212 degrees until it becomes pressurized. Then the heat rises dramatically. You actually want to build a leaky box that the steam will pass through and pressure and temperature will not build out of control.
Be careful. I've unfortunately seen the results of skin damage from pressurized steam and the image will last with me forever. Build it loose and generate plenty of steam. Cut a drain hole i the box and tip the box down hill a bit to allow condensation to escape. Put the work piece on a shelf to keep condensate from touching it and staining. Good Luck.
fmr

[Neil Strong]

Cut a drain hole i the box and tip the box down hill a bit to allow condensation to escape. Put the work piece on a shelf to keep condensate from touching it and staining.

Those suggestions from Faust were the only additional ones that I would have made from watching Jake Darvall steam and bend his Windsor Chair spindles. Website here

If you have steamed flatware before you will know that you will have to sand again after steaming... it sure lifts the fibres.

....

[Allen Neighbors]

But here on day three...my caulking is still not cured

It's been in the 80's...but the humidity is 2000%. The caulk is still partially white. Can't risk it. Gonna hafta wait.

Good. Don't you mess up now. My money's on you!!

[Tom Sherman]

Lots of interesting stuff here John, I am wondering if your backing being made of wood might need some sealing to prevent them from soaking up moisture. Just a thought and maybe not very important. Luck to you my friend

[Scott Lux]

but the humidity is 2000%

No kidding. I went fishing yesterday and had trouble figuring out where the river started and the air stopped.