Build a Complete Wood Steaming System
This system will help you build a wood steaming system for making canoes to rocking chairs. This system will show you how PVC can be used to boil water and make steam for your steam box. By E.Parvis
This is a PVC Pipe system with an electric heating element, the same as used in water heaters, it has been built many times and does work very well.
Note: The info below is just an overview of the system, the plans give details and methods to build this system.
Contents
Steps
- The heating element electrical connections must be enclosed in a waterproof box at the end of the "T" area of the santee and have a cord with a grounded plug and wire (green wire) grounded at both ends of the cord. The PVC is in the form of three main parts, a (90) degree fitting at the bottom for the inlet of the water supply, a (T) fitting or santee (sanitary fitting) in the middle with the heating element attached and third, a 14” straight section on top with the steam hose attached to provide steam to the steam box, this is the riser. The location and size of parts in relation to each other along with the element size makes for a boiler that works very well or one that turns into a white sticky ball.
- In addition to the boiler, it is important to have the proper water supply feeding the boiler as water is boiled/steamed away. A 5ga. plastic container works fine. The {{safesubst:#invoke:convert|convert}}. container is large enough to supply water for several hours without having to constantly watch the water level. The supply tank sets on a supply stand next to the boiler. The stand is built of 2x4’s and plywood and is about 14” high, this lets the water level in the boiler be the same as in the supply tank.
- Build the supply stand with a ¾” plywood deck on top the stand about 18” square with a 3” hole in the center for the tank connector to pass through. The supply tank sets on the stand and has a hose running from a through the tank connector to the bottom of the boiler, use a ¾” diameter clear braided PVC hose. You will use about ¾” of water from the {{safesubst:#invoke:convert|convert}} container per hour. Mark a line at the full point, that which is the same level as the water inside the PVC boiler when the boiler is full or within 2” of the top of the boiler, and then another line about 3” down from that on the supply tank. This gives several hours of steaming without having to refill the tank. It also give you a bit or room for not refilling the tank if you're in the midst of bending a piece of wood when the water level reaches the bottom mark, this helps protect the electrical element and still give you lots of steam until you can add water to the supply tank.
- Having a water supply to feed the system without interrupting the heating and steaming process makes all the difference. You can refill the supply tank and not interrupt the boiler or steaming process.
- As with most wood steaming systems, the steam box is a big problem. You want a box that will stand up to the water, hold the heat, and move steam from back to front in an even flow. Also, provide the space for several pieces of wood to be steamed at one time and be able to be of many different lengths of say {{safesubst:#invoke:convert|convert}} to as long as {{safesubst:#invoke:convert|convert}}.
- Use treated lumber or treated plywood covering it with foam/glass insulation. It should be noted here that other woods will work just fine, woods as cedar and Cyprus, but they cost a lot more. The box has an outside size of 11-1/4” x7-1/4”x {{safesubst:#invoke:convert|convert}} to {{safesubst:#invoke:convert|convert}}. It is possible to use a steam box up to {{safesubst:#invoke:convert|convert}} if you use the larger 4” PVC boiler, same system, just using 4” PVC in place of 3” PVC. The steam box must also be set at a slight angle to induce good steam flow from back to front inside the box, the back side of the box sets lower then the front. This tilt helps keep the condensate to the back where the drain hole is and off the wood being steamed. To steam wood in a box it is necessary to keep the wood up as close to the top of the box as possible; this is where the heat and steam are. Another problem with the steam box is that most people try to seal it up. However, if you seal ALL the holes, the box becomes a steam bomb.One of the ways to prevent this is to not use latches or locks on the door. The door also should have a 1/4" gap at the top of the door to induce slow but safe steam flow through the box. What you want here is a steam box that is safe and will not fall apart after a few uses, while giving you good bendable wood time after time.
- The steam box stands over the PVC boiler/steamer and water supply tank supported by legs. Each set of legs have a cross supports for the box to set on. The support on the back set of legs is about an inch lower than the one on the front legs. This give the steam box the upward tilt at the front for good steam flow form back to front. The legs can be of any length, but they should be tall enough so it is easy to add water to the supply tank when necessary and to have good access to the steam box door and the wood being steamed.
- This boiler, water supply tank/stand and steam box above, sets on a ¾” plywood platform with a 2x4 frame under it. Adding locking wheels makes it quite portable. This makes it easy to roll out of the way and store when not in use and when you are ready to steam some wood, you can roll it right over to the job area. Being portable and moving it close to the job means that when removing wood from the steam box, you lose less heat and bending time is extended, seconds count at this point.
- Note, never move the steam system when plugged in (in use), keep safety your biggest project!
Tips
- Selecting Bending Stock
- The follow list of hardwood has been selected from a list of 25 hardwood species tested by the U.S. Forest Service for ease and quality of bending. These are the best 17 of that list.
- Read all you can find about wood steaming before you start building your system.
- Order from best to worst:
- The results of the test are from one evaluation, so based on individual trees and different growing locale, variation in the results should be expected.
Warnings
- Steam is VERY DANGEROUS, WORK SAFE.
- Use gloves and safety glasses when opening the steam box door.
- Never move the steaming system while the boiler is plugged in.
