Hot Pipe Bent Salad Tongs
Bending wood is one of the most exciting and magical things a woodworker will ever experience.
Hot pipe bending is one of the simplest things to set up and produces some of the most amazing results. If you don’t have any of the necessary supplies to create this set-up, a trip to the hardware store is in order.
Keep it Simple
You don’t need anything fancy – just a pipe, a torch and some wood to make the cradle.
Cradle for the Torch
Build a small cradle to hold the torch stationary. The last thing you want to do is quickly grab a rolling torch.
Only a small flame is necessary to heat the pipe to the proper temperature.
The Right Temperature
Somewhere between 200° F and 250° F is the perfect temperature for hot pipe bending.
The tub is an easy solution for a spot to soak the parts prior to bending.
Apply light pressure and take your time.
Let it Set
For a sharp bend like this, hold the part on the pipe for a few minutes, allowing the wood fibres to totally reposition themselves.
Account for spring back by slightly over-bending.
Check the Shape
Mount a template to the top of the jig for easy reference.
Clamp the part to a drying jig to let it set to the shape.
Add some gentle and user-friendly curves.
Cut With Care
Avoid putting fingers in between the pieces “just in case”.
A piece of wiggle wood works great as a curved sanding block.
What You Will Need
You will need a metal pipe about 6″ long with an outside diameter of 1 ¼”, as well as the matching flange. The rest of the bending jig can be made of small scraps of wood. The pipe is heated with a propane torch – pick one up if you don’t have one.
Mount the pipe to a board with the corresponding flange. Drill a large hole in the mounting board for the torch to shine through and into the pipe. The board can simply be held vertically in a vise. I chose to attach the board to a platform so I would have a portable set-up I could use in places that I don’t have a vise. Before using the pipe for bending, sand off any coating it might have on it.
I decided to create a simple cradle that would allow me to adjust the angle of the flame. With a bend in the neck of the torch, a slight rotation of the propane cylinder changes the angle of the flame. I found being able to change the angle of the flame to be beneficial in getting the right temperature on the working area of the pipe. Also, I make a template for the shape I’m bending and attach it to the top of my mounting board so I can check the shape I’m bending against it as I go.
Temperature is Key
Like many things, if it’s burning, it’s too hot. You will find that only a small flame is required to heat the pipe to the proper temperature of about 200 to 250º F.
If you are getting burn marks on the surface of the wood, the pipe is too hot. A stovepipe thermometer is an inexpensive way to check the pipe for the correct temperature. Rotating the torch to increase the angle and intensity of the flame to the working area of the pipe is an extra bit of control over the temperature.
Depending on the day and the way in which the torch was burning, I found I could get the right temperature by aiming the torch a little more down the pipe rather than up at the top of it.
Make it or Break it
The pieces you wish to bend should be straight-grained and free of knots and any other imperfections. I often select and plan my pieces to have knots or figured areas where the milder bends are, as they add nice character, and keep the straighter grain for the tighter bends. If the grain is not straight/parallel, you are likely to see fibres lifting on the outside of the bend. You will have much better luck bending air-dried lumber than kiln-dried lumber. Hardwoods such as ash, oak and walnut bend especially well to a tight radius. Woods like maple and cherry will bend but not to as tight a radius. I am never afraid to try bending a new species of wood but I recommend ash, oak or walnut to start off with. The maximum thickness you can bend will vary; ¼” is the thickest material that can easily be bent to a tight radius but it is possible to bend material up to ⅜” with this approach, especially with a more gradual bend.
Soak the pieces in water for three or four hours before bending. Depending on the size of your parts to be bent, you may be looking for a place to soak them. I found an inch of water in the bottom of the bathtub to be an easy solution. Just wait till the “boss” isn’t looking. For these particular tongs, I started with pieces ⅛” x 2 ½” x 30″. Make an extra piece or two and don’t expect a 100 percent success rate.
Don’t rush it! Work the piece over the pipe, heating the section to be bent. Apply only light pressure to the piece. You will know when the wood is ready to bend. The heat loosens the lignin bond around the wood fibres. A ⅛”-thick piece of wood will take just a few minutes to become hot enough to bend. can actually feel the wood let go and loosen up. The trick is not to jump the gun. Apply consistent pressure. Allow the wood to do its thing: compress and reposition its fibres. Do not heat the wood on both sides. The fibres on the outside of the bend remain the same length and the fibres on the inside of the bend compress.
Heating the outside of the bend may cause the fibres to fail.
Once the bend has been made, you will find the piece will spring back. Hold the shape around the pipe and let the fibres totally reposition themselves. For this 180-degree bend, I clamped the part around the pipe for a few minutes. This actually cooks the part and sets the shape minimizing spring back. You want the piece to be as close as possible to your template without needing to force it into place. Once the shape has been bent, it should be held in a way that allows good airflow to allow even drying. Only light clamping should be necessary. The drying process can be sped up with a fan. Use a moisture meter to ensure the piece is dry before the final shaping and sanding.
Hot glue a scrap in between the tongs, to hold them in a more parallel arrangement. Use a scrap that is narrow enough to be out of the way of the curved shape to be cut. Make a template of the curve to be cut, out of thin cardboard and use a bandsaw to cut the curves. A piece of wiggle wood works great as a contoured sanding block. I finished the tongs with a food-safe salad bowl finish. These tongs are a great way to finish off a set of bowls. They are great for buffet dinners and potlucks where you only have one free hand. Good luck and happy bending!
Note: The propane cylinder is made to be stored and used in an upright position. To use the illustrated technique safely orient the pipe in a vertical position, so the propane cylinder can remain upright.