View Full Version : Making Steam for Bending Wood

Nicholas Carey
01-31-2002, 09:56 PM
I'm starting a project to make an electric steam generator. It will be a strange hybrid of toilet and steam generator http://media5.hypernet.com/~dick/ubb/smile.gif

Basically, it will consist of a tank, fed via a garden hose via a toilet's fill valve that's installed in the bucket. This will be connected to and feed the steam generator itself.

The steam generator consists of a length of 2" ID galvanised pipe with a Tee at the bottom. The side of the Tee is reduced to 3/4" and will be connected to the bucket. The bottom of the Tee has a bushing reducing it to 1" which is where the hot water heater element will be installed. The idea is that the float valve will be set up to maintain the water level a couple of inches above the hot water heater element. The whole thing will be lagged and insulated and attached to the steam box with a flange or something similar.

Since plumbing has never really been my forte, I've looking for suggestions and ideas:

1. The pipe is NPT threaded (tapered), the hot water heater element isn't. Any ideas on a fixture that will join the two or is a trip to the machine shop in order to have the NPT fitting re-tapped? I checked, a 1" tap runs about $US 80 -- too rich for my blood.

2. Any ideas on how the hot water heater element is to be wired. Information on that appears to be sketchy. A 220AC circuit is three wires. The hot water heater element has 2 terminals. Obviously the hot lead (black) goes to one and the neutral lead (white) goes to the other. My assumption is that the ground lead (green) needs to go to the pipe housing the heater element. Am I correct in making this assumption? I tend to operate under the theory that fires and electrocutions are, generally speaking, a Bad Idea.

3. Hot water heaters have a sacrificial anode -- is it worth installing one in the steam generator?

4. What about a thermostat to prevent overheating?

Ed Harrow
01-31-2002, 10:21 PM
Before you get too far, you might want to dig up a copy of the Boatwright's companion - Allen Taube. He's got a section on an electric steam generator. The biggest issue, from his perspective, is that the heater element is toast if it runs out of water (perhaps that's your toilet float fix). I think, somewhere within this place I once posted info on it, but with the demise of PP the picts are likely kaput. If you're interested I'll see if I can dig up more information.

Frank Wentzel
02-01-2002, 11:30 AM
A 240 volt circuit is a 4 wire circuit. Generally they are coded black, white, red and green. Between the red and white or black and white you have 120 v. Between the black and red you have 240 v. The white is neutral, green is ground and red and black are hot wires.

/// Frank ///

02-01-2002, 11:42 AM
I wish I had kept some of the pictures of mine. I used dishwasher heating elements (because they were free) they could also be formed into any reasonable required shape by gentle persuation, operated on 120 V, and when run dry were the toaster not the toastee. I didn't go for an elaborate water charging system, but I have thought about similar systems for watering the dog. When I was generating steam, I would periodically heft the bucket and refill when it seemed to be getting light. Running at 1 KW, I got plenty of steam, and only had to top off the tank every hour or so. You could probably do a precision job with a bathroom scale.

bob goeckel
02-01-2002, 01:29 PM
all i have to do is tell swmbo i'm thinking about another boat and steam comes right out both her ears and i can go to work.

Tom Wilkinson
02-02-2002, 11:12 AM
I made my steam box using a wallpaper steamer from lowes or home depot. Holds enough water to steam for 2 hours or more and comes all ready to go. You just have to adapt the hose to your steam box but that was a peice of cake. I think the cost was about 30 bucks.

02-02-2002, 11:40 AM
As to the pipe issue.

I just replaced our water house water heater last month. The local plumbing supply house offered 1" and 3/4" X 18" flex copper tubing with whatever fitting you wanted on either end for $5.


02-02-2002, 03:15 PM
Does anyone have any detail pictures of their particular steaming apparatuses? -sp? I too have it in the back of the to do list to start gathering materials for my shift from the renovation of wooden boats to the building of wooden boats. A steamer will be one of the first things I need.

If everyone could post some pics of their steamers, it would be greatly appreciated by the "green" forumites like myself...


bob goeckel
02-02-2002, 04:54 PM
sorry lumberdude, can't get swmbo to hold still for a picture.

Greg H
02-02-2002, 05:48 PM
From a couple weeks ago:

Ed Harrow
02-02-2002, 08:58 PM
Our sponsor has a book about reframing, replacing keel, floors, etc. There's a whole section on steam generators.

02-02-2002, 10:27 PM
What size is the thread for the heating element? I may have a NC 1" or a NF. CWB may have the right tap in the warehouse, there is a Greenlee set up there- in cosmoline. It may be necessary to get a smaller reducer to bore out the NPT and tap in the element thread.
It does not look good for Glory Be. Nothing showing at the slip. They are raising boats on Monday. Coriolis is a briquette above the waterline, interior is intact.

Nicholas Carey
02-02-2002, 11:39 PM
Originally posted by plimsol:
What size is the thread for the heating element? I may have a NC 1" or a NF. CWB may have the right tap in the warehouse, there is a Greenlee set up there- in cosmoline. It may be necessary to get a smaller reducer to bore out the NPT and tap in the element thread.

Paul -- I thinks it's 1 in SAE, but don't quote me on that. All the parts are in the shop on the workbench to PIRATE's port, by the drill press. I'm out of town (Rachel's grandmother's funeral is tomorrw and then we're driving to Detroit, Chicago, and Duluth -- I'll probably be back next weekend is what it looks like.

It does not look good for Glory Be. Nothing showing at the slip. They are raising boats on Monday. Coriolis is a briquett e above the waterline, interior is intact.

Boo. That's a pity. I hope they can save CORIOLIS, it would be a shame to be the first owner to lose a Concordia yawl on your watch. [for the unitiated, this is in reference to the recent fire at the Seattle Yacht Club -- thirteen boats sunk, 20-some damaged -- there's a thread going in misc about it. GLORY BE is a little 1914 double-ended raised deck cruiser -- about the cutest thing you ever saw.

See you next weekend..

[This message has been edited by nicholasc (edited 02-02-2002).]

02-03-2002, 08:38 AM
There are several types of hot water heating elements, the screwed type you mention and a bolt on style as well, which usually has 4 bolts and a gasket mounted on a plate. I would try to get hold of one of the bolt on types. You could then weld a plate on the end of your steam tube, drill the holes to match the element and fasten it with the gasket in place and a 4 washers and nuts. Probably be a lot easier and less work than trying to cobble different threads together. Also, you could use a 115 volt element, (they make them in both voltages, same wattage) and just put a plug cap on the end of the wires and use a standard 115v receptacle. As for the thermostat, the ones that come with hot water tanks have a high limit shut off, which prevents the water from turning into steam, a very dangerous prospect when a closed system (as in a house) allows the water to expand 1700 times, causing a bomb like effect. So if your system is designed to open to the atmosphere, I would not worry about a thermostat.
With the ground wire, either 115 or 230 volts, I would attach it to the galv. pipe, making sure it is well grounded through the receptacle and into the panel box.

OK, now, instead of having the element in the end, why not use a T at the mid point of your steam box, dropping down, where the element will sit. You could pipe your water source to this T, off yout toilet tank, remove the flapper mechanism, and have the water seek its own level. Feeding the toilet tank with pressurized water through the ballcock assembly, which will controll the level of water in your resorvoir tank, and gravity feed the steam box from same tank.

Clear as mud? OK, both 230 and 115 volt wiring are 3 wire runs, 115v being one power, one nuetral and a ground. 230 volt being TWO power, (115 each side), and a ground.

Hope this helps,

02-03-2002, 08:49 AM
Sorry, forgot about the sacrificial anode deal. I would not worry about it. These are usually magnesium rods, but their effectivness is a matter of debate. You will be replacing many elements over time regardless of a sacrificial anode or not. You might want to however, depending on the hardness of your water, de-lime the steambox as required. You can get de-liming solutions from most boiler suppliers, or plumbing wholesalers.

Art Read
02-03-2002, 12:39 PM
Lumberdude... It ain't "rocket science". I worried WAY too much about it 'till I just DID it. The main thing, is to avoid building it so carefully that you actually create steam PRESSURE! There's a reason that people who run steam plants are required to have a license. It's DANGEROUS! A little "leaking" is a good thing in this case. I've used variations of the setup you see below for all my steaming projects. All you really need is some boiling water and a way to "collect" the vapor and carry it to the wood you want to bend. But get that "Frame, Keel & Stem Repair" book. Worth every penny.


02-04-2002, 01:40 PM
The original notion, IMHO, is way over-thought. You need a clean (new) gas can, a high btu burner (& a barbecue sized propane bottle) like those turkey cookers at Lowes, a couple of feet of car radiator hose, and a wooden box sized to fit your needs. The rube-goldberg setup isn't needed.
Check past threads on steaming. More than you'll ever need to know http://media5.hypernet.com/~dick/ubb/biggrin.gif

02-06-2002, 07:54 AM
Man, I spent 1/2 a day a week or so ago looking for a new metal gas can and finally gave up. All I could find is plastic. I gonna try the brewpot and a plywood cover.


Just found one in Idaho by searching for "Metal Gasoline Can" on the internet. After weeding through all the links about not filling a can in the back of a pickup, I found one to fit the bill for $29.95. Spouts too. That wallpaper steamer is looking better all the time!

[This message has been edited by Fitz (edited 02-06-2002).]

Hugh Paterson
02-06-2002, 10:55 AM
Man I must be missing somthing, why not plumb the steam generator from a commercial wallpaper stripper onto your box, Heath Robinson....eat yer heart out.


02-06-2002, 03:25 PM
The commercial paper stripper may be fine if this is only a once-ever job. What if there's another, and another? And think of the points you get when visitors ask, "What's that there do-hicky for?" and you explain steaming to them http://media5.hypernet.com/~dick/ubb/biggrin.gif

Tom Wilkinson
02-06-2002, 06:18 PM
I have to agree with Hugh. Is there a reason to go through all of this when wallpaper steamers are readily available? I am using a 39.00 home depot special to steam parts and it works great. It produces about two hours worth of steam, plugs into a 110 outlet and stores easily in the box it came in. Do the propane powered jobs create more or better steam or what? What am I missing?

02-06-2002, 08:25 PM
Two weeks ago, I built a steam box to Allen Taube's specifications I found in 'Boatwright's Companion' . Looks like nicholasc and I were doing the same thing that weekend. After I burned out the first heater element in week one, I added a bucket and toilet tank valve in week two.

If nicholasc is like me, he's been there and done that by now. However, my steam bending is just starting so I'd like to compare notes. One of us will surely benefit. So, here's my $0.02 on steam box construction.

1. Element to 3/4" NPT - Had the same problem. Put them in a vice and tightened them up. Did not leak.

2. 220V Wiring - I used 70 feet of 6-4 to get from a 220V 50 amp dryer outlet to the 45000W heater element. I connected the two hot conductors (black and red) to the two element terminals(the hot conductors are the two slanted leads in the dryer outlet). The neutral (white) and ground (bare or green) I connected to the body of the apparatus based on my interpretation of Taube's diagram. This provides 220V to the element. Got reeeal hot and didn't electrocute myself. This is certainly not to code so don't try it unless your sure it's safe.

3. Anode - don't need it. It keeps anareobic bacteria from growing and making your water smell bad.

4. Thermostat - don't need it. Water boils at 212F under atmospheric pressure- can't overheat it. Element is either on or off - can't protect it. What would a thermostat do?

5. To connect heater to box, I used 3/4 ID high temp hose (radiator hose) provided by my friendly boatyard.

6. Steam box was made from 1 sheet of 1/2" plywood just like Mr. Taube suggested. Hinged doors on both side - one opens up - one opens down.

7. Tried placing foam insulation inside box. Warped and fell down in first hour. It's all gone now.

8. Five gallon bucket is used as water reservoir. Toilet tank valve in bucket keep water level constant while steamer is running. Haven't burned out element #2 yet.

9. Cost - I guess I got $130 bucks in elements 1 & 2, pipe fittings, 70' of 6-3, plywood and 2x4's. Hope this works or I'll have an expensive lesson.

I get the confidence I need to keep going with my restoration project from reading this forum.

[This message has been edited by JDougM (edited 02-06-2002).]

Captain Mike
02-06-2002, 10:35 PM
I've used a propane plumbers burner and metal gas cans for more than 20 years.Cheap,simple and easy.

02-07-2002, 12:32 AM
This site may be of interest to you


Hugh Paterson
02-07-2002, 07:59 AM
For all those working on larger projects. you should have a looksee at the article in Classic boat [UK] (Feb issue 2002) "Boil in the bag." Neat stuff, the steam generator's a beer barrel with two pipes leading from it into a plastic bag, thats around the plank in_situ on the frames of the intended victim (boat). It seems it works on 5" planks.