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Methods of Bending Wood
By: Rob Smith

After building a few simple projects in your shop, you may have the desire get more creative and build something that requires more advanced techniques in woodworking. One of these advanced techniques is wood bending.

There are a few different methods used to bend wood. I will try to give you enough information on most of these wood bending techniques to allow you to get started on your way to more creative furniture. These methods will include Steam Bending, Kerf-cut Bending, Laminated Wood Bending, and for small pieces of wood, Microwave Steaming. You will also need to know how to prepare forms and molds before you can bend the wood.

Forms and Molds for Bending Wood

Before attempting to bend wood you will need to have a mold or form set up. Steam bent wood needs to be placed in the form and clamped in place as quickly as possible after being removed from the steam box. Laminated wood also needs to be placed in the form and clamped before the glue begins to set.

Most forms and molds are easily made from MDF. You will have to glue multiple sheets of MDF together to get the thickness that is about the same as the height of the piece of wood you are forming. After you glue up the MDF and it is dry, you have to square up the ends, for easier clamping later on. Then trace your shape on the form, and cut it with the bandsaw, take care to save both sides of the form. They need to match like a puzzle piece. Then smooth out the cut with a pattern makers file and/or sandpaper, to refine your form’s shape to perfection. Finally, glue a strip of cork to each part of the form. This will help to provide equal clamping pressure to the piece and a slight cushion help prevent marks on your piece of wood.

Another alternative for a form is a theory I have been thinking about. I have not tested this and can not say for sure it will work. If you would like to experiment with it, please email me and let me know if it worked. I will provide the details below, think about it and use your own judgment in whether to try it or not.

My thought is that a peg board form would work for sweeping curves. You would start by drawing out your shape on a piece of 8/4 or 2” hardwood stock. Then you would drill and place hardwood dowels at the apex of the curves. When the dowels are in place, you are ready to place your work piece into the jig and clamp it to the dowels as the blue marks indicate in the diagram below.

Steam Bending Wood

Steam bending wood is probably the most widely used and accepted method of wood bending. It has been used for ages

To construct a steam box you will need.

• A heat source to make to steam
• A container to hold the water to be heated
• A hose to connect the container to the steam box
• A box to hold the wood to be steamed. Can be either a PVC pipe or a wood box.
• Various fittings, clamps, and screws to put the steam box together.

The heat source can be a camp stove, or just a hot plate. Open flames in a wood shop can be dangerous, so I would prefer a hot plate.

The container to hold the water can be anything you want. A tea kettle works well, but some people use NEW and UNUSED metal gas cans, pressure cookers, etc. You have to be able to attach a hose to it somehow, with fittings and such.

The steam box itself can be made from PVC pipe, metal pipe, or a simple wooden box you make from scraps in the shop. It don’t really matter that much. Steam has to be able to escape, or else the pressure will build and cause it to explode. But you want it to hold the steam enough to heat the wood and force water vapors into the wood. Roy Underhill from the Woodwright’s Shop uses a wad of rags to plug the end of the box, and you can see the water dripping out of the end. If you use a PVC end cap, drill a hole or two in the end to allow the steam to release to pressure as it builds.

Now just assemble everything and try it out. Be careful the steam will heat everything up, so use gloves. The general rule of time is about 1 hour for every inch of thickness being steamed. Use this as a starting point, and adjust your time as needed.

Laminated Wood Bending

Laminating wood to bend it is a fairly simple process. You will still need a form or mold but you won’t need to build a steam box or risk burns with steam. Thin pieces of wood bend easier than thicker ones, but aren’t as strong. So by laminating thin strips of wood together in a mold or form adds strength and when the glue dries it will hold the shape also.

To bend wood with lamination you need to use thin pieces of stock, longer than your final length needed, you will trim to length after the bending is complete. To get the thin stock you can either buy it, or make your own by resawing thicker stock with your bandsaw. Pieces 1/8”or thinner will be easier to bend, but depending on how thick you want the piece in the end, you may need use a lot of pieces and glue.

After you have your form or mold ready and all your thin stock ready, all you do is spread glue on the pieces and stack them together in the form and clamp. When the glue is dry you can dress the edges and trim to length.

Kerf-cut Bending

Kerf-cut bending is done by using your saw to cut slots across the stock. This will allow the stock to be bent because the kerfs can compress together. The kerfs are usually only used on the inside of the bend. If you want to make a more complex curve, perhaps an S- shaped curve, you would cut the kerfs on the inside of each bend, then you would use a veneer you cover the entire piece.

Microwaving Wood to Bend it

Basically this is just steaming, and is used for small pieces of stock. You wrap the stock with a wet paper towel and microwave for a few seconds. The microwave heats the wood and water just like a steam box. The time will vary depending on your microwave, the species of wood, the wood’s moisture, the dimensions of the wood, etc. You will have to experiment to find the proper amount of time, start out with 15-20 seconds and work you way up from there.

Finally

There are a few more methods of bending wood out there, but they aren’t widely used and there isn’t much information available on them. These methods described above should be all you need to get started in the shop making more creative pieces of furniture. You might have to experiment a little but that is part of the fun of working in the shop, trying new things. So have fun but be careful.


 
 
   
 
     
   
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