Oct 27, 2010

How to Build and Use a Sawdust Stove

By B.R. Saubolle, S.J.

As we who live in the industrialized nations of the world are increasingly forced to tighten our belts and live less energy-intensive lives, we might do well to examine the gentler technology of the so-called "underdeveloped" countries for "new" recycling and fueling ideas. I'm indebted, therefore, to B.R. Saubolle, S.J.—of Katmandu, Nepal—or telling my readers how some inhabitants of the Indian subcontinent derive useful heat from what is commonly considered a waste material in the U.S. and Canada. Perhaps we need more of this "reverse" Peace Corps work.—MOTHER.

One of the simplest fuels for cooking and for heating the house in winter is sawdust . . . a waste product which is usually thrown away and which, therefore, is obtainable free or at nominal cost. (True, not everybody lives conveniently near a sawmill or lumberyard, but the same objection applies to many other alternative sources of power. Not everyone has a stream running through his property to generate electricity, or keeps cattle to supply manure for methane. We must make use of whatever resources are available to us.)

Sawdust will burn properly only in a specially constructed stove, which is very simple to make and costs practically nothing. The fuel always lights with only one match in such a unit, and can be kept ablaze for long periods—six, eight or even twelve hours if desired—with absolutely no smoke, no blowing or fanning and no refueling.

Once lighted, such a stove burns until all the fuel it contains is consumed. It can then be recharged and lighted again. Such a device is ideal where steady heat is required for hours on end with no attention (to provide day-long hot water, for instance, or to keep a sickroom cosy and warm through a chill winter's night).

To make a sawdust stove, take a large paint can, remove the top and cut a two-inch hole in the middle of the bottom. Set the container up on three legs, and the stove is ready. The only "tool" you'll need to make your burner work is a smooth round stick or length of water pipe which will fit through the hole in the bottom of the can. It should be long enough to protrude four inches above the can's top edge when the shaft is passed vertically through the stove and its lower end rests on the ground.

It is absolutely essential that the fuel for this stove be bone dry. If it's slightly damp, it will smoke. . . and if it's very damp it won't light at all. Dry sawdust burns wonderfully well—sometimes even with a blue flame—and is entirely smokeless. It does give off some fumes, however, and the room where the stove is in use must be well ventilated.

To load the burner, insert the stick or pipe through the hole in the bottom of the can and hold the shaft straight up while you pour sawdust around it. Every now and then, as you fill the container, press the fuel down—the harder the better—to make it tight and compact. When the can is full, completely cover the top of the sawdust with a thin, even layer of sand or ashes. Then twist the pipe back and forth and carefully pull it out of the packed fuel. You'll have a neat hole—which will act as a chimney—right through the mass.

The sawdust stove is easy to light. Just crumple a sheet of newspaper accordion-fashion and push it gently down the chimney until it protrudes at the bottom. Put a match to the lower end, and the homemade heating unit will require no further attention whatever until the fuel is completely consumed.

The powdered wood burns from the center outward, the hole gradually increasing in diameter until there is no sawdust left and the flame dies out. The rate of consumption is about an inch and a half to two inches per hour (the figure varies slightly with the quality of the fuel and how tightly it's packed). A stove one foot in diameter will burn about six hours, and one eight inches across will operate long enough to cook a meal and produce some hot water to wash the pots and pans.

The amount of heat produced is regulated by the depth of the container: the longer the chimney, the hotter the flame. A tall, narrow stove will become very hot for a relatively short time, a broad, squat model will give a gentler heat for a longer period and a tall, wide drum will burn both long and hot. Calculate the dimensions to suit your requirements.

The basic design can be adapted to special purposes. For example, a good sawdust-fired kitchen range can constructed in either of two ways: [1] Two or more legless drum stoves can be bricked in, with a small opening b low each to admit air and remove ashes. [2] The stove can be built brickwork alone, without drums, and two-inch round hole made through the wall into the bottom of the firebox. This second model is filled with the help of two sticks or pipes. One is first is pushed through the front opening least as far as the center of the stove and the other is held upright so that rests on the horizontal rod. Then the unit is packed with fuel and both sticks are drawn out.

The basic sawdust burner may be modified into a space heater to d laundry on a rainy day or warm a living room on a cold night. To adapt a can stove for this purpose, a second container (with its top removed) turned upside down and fitted snug onto the upper rim of the heater. This radiates warmth into the room. An opening is made in the upper chamber near the top, to receive a stovepipe which carries any fumes out through a wall or window. If desired, a hole with a removable cover could be cut in the top to make an open burner for heating a kettle.

Whether you decide to modify the basic sawdust burner I've described or not, I think you'll find the device presents a most efficient means of using a common waste. I know you'll also finds that it produces steady, reliable heat for cooking and/or warmth.

Woodworking for Mere Mortals: A whole LOT of uses for sawdust

I received an email from Adam Reed wondering if I had any suggestions for what to do with sawdust. Sure, we occasionally mix it with glue and make wood filler, but mostly it all goes into the garbage. It seems so wasteful. So I posted the question on the Mere Mortals Facebook page a got a bunch of good suggestions. But special kudos goes to Walter Masten who has already been compiling a list of ideas he has run across and has even taken the time to categorize them. I have taken the liberty to edit his list as well as add suggestions from people on Facebook and put them all in the following list.
I can't personally guarantee the veracity of any of these as they are tips from around the web, but most seem like reasonable uses for sawdust. Feel free to add any of your own in the comments section. I just hate throwing stuff away! Sawdust Uses in the Wood Shop
  • Fill wood holes and defects. Used by professional floor refinishers, very fine sawdust or "wood flour" makes excellent, stainable filler when mixed into putty with wood glue. The wood flour from my sanders I put in small zip lock sandwich bags, label them as to wood type and save for project repairs or repairs to wood structures around the house.
  • I occasionally go through my old cans of paint, finish, and stain to throw away. By law you can’t throw those as a liquid in the landfill. But you can if they are dry. I pour the liquids into a bucket of saw dust until it is absorbed nicely and let it dry. Then I dispose of it.
  • You can pour them into moulds coated with wax to make stuff. You just need to mix them with a bit of resin. Turns out like MDF, except whatever shape you want. Paintable, stainable and super easy to sand and get a glass like finish on.
  • I use mine to protect the concrete floor of my shop. I have found that a 50mm thick layer prevents scratching of the delicate concrete surface and deadens the noise of falling tools.

Sawdust Uses in the House/Body/Cooking

  • Lighten up cement. Sawdust mixed into mortar has long been used when erecting cordwood walls to aid in bonding the logs together. Do the same when casting lightweight vessels and moisture-loving planters.
  • Use wood shavings as a packaging material in place of Styrofoam peanuts, bubble wrap, and other synthetic material.
  • Clean a floor. Moisten a pile of sawdust with water and use a push broom to sweep it around the concrete floor of your garage, basement, or shop. The wet sawdust will capture and absorb fine dust and grime.
  • Cedar can be put in ziploc bags and put in closets.
  • Pack a path. Tamp sawdust into a dirt walkway to curtail erosion and create a soft, fragrant pathway through your garden or wooded lot.
  • For areas that get snow. Use untreated wood shavings for traction on sidewalks etc. better for the plants than using salt products.
  • Get a grip. Winter loggers spread sawdust on their truck paths. It provides traction and strengthens compacted snow while protecting the ground underneath.
  • Use sawdust to stuff decorative pincushions for gifts at holiday time. Pins and needles won’t rust.
  • I use some of my hardwood shavings in my side fire box meat smoker for added flavor.
  • Use sawdust for soaking up oil spills. Just sprinkle it on, let it sit for awhile and then sweep up. Sawdust can also be used to clean greasy, oily hands and tools. Sprinkle it on, massage thoroughly, and add more sawdust as necessary. Better than using messy newspapers or wasting paper towels.

Gardening with Sawdust:

  • If you use a lot of sawdust in your vegetable garden it might turn your soil acidic. Plants need a somewhat neutral PH to be able to pick up nutrients, so add some lime. Do a soil test to determine how much lime.
  • Walnut sawdust contains an herbicide and will kill tomatoes and other plants.
  • When using sawdust in gardens always add extra nitrogen, because the decay bacteria will use all available nitrogen and leave the plants with the “yellows.” Eventually the nitrogen is freed, but that may take a year or two.
  • The larger the pieces of wood, the less nitrogen starvation is a problem.
  • Chase away weeds. Sawdust from walnut wood is a natural weed killer. Sweep this variety between the cracks of your walkway.

Sawdust and Woodchips for Fuel

  • We burn most of ours in the boiler to make the steam to dry wood.
  • Mix it with wood chips and melted paraffin. Pour into empty tuna fish tins for emergency fuelor camp fire starter
  • Another use for hardwood shavings and sawdust is in ceramic raku firings. It won’t use up great quantities of waste sawdust, but maybe you could get a free pot or two out of the deal, and it is fun to watch.
  • How to build and use a sawdust stove
  • The Fire Brick: I start with a large tub (about 2′ * 15″ * 15″) 3/4 full with sawdust. To this I add 15 – 20 litres (3-4 gallons) of the biodiesel byproduct and mix a bit. I leave this for a day or 2 and then mix again. I repeat this until the sawdust is evenly mixed. If it is too moist, I add more sawdust and mix this sawdust in the top layer. When I have sawdust which can be squeezed in my hand, and it retains its shape, but crumbles when pushed from the side or top, it is ready to be packed.
  • Make a fire starter. Melt candle wax in a nonstick pot, add sawdust until the liquid thickens, pour into an empty egg carton, and let cool. Use the briquettes to help get a fire going.

Animal Woodchip and Sawdust Ideas

  • Certain species of woodchips and sawdust make great beddingfor cows, horses, chickens, pigs and other farm animals. Beware Black Walnut though… it’s highly toxic to animals.
  • I also bag some red cedar up in burlap bags and sell them for $10 as dog bedding.
  • As bedding for small mammals gerbils, mice, rats etc.
Sawdust Uses in Projects

  • Make fake snow. Mix sawdust with white paint and glue to cover holiday crafts with simulated snow.
  • Lighten up cement. Sawdust mixed into mortar has long been used when erecting cordwood walls to aid in bonding the logs together. Do the same when casting lightweight vessels and moisture-loving planters.
Sell or give away Your Woodchips and Sawdust
  • I cut a lot of Eastern red cedar and I bag the sawdust up and sell it. I get $3 a plastic garbage bag; using kitchen bags (I believe they are 15 gallon).
  • Craigslist. Thanks to CL, I have a regular picker-upper now. I let her know, leave them out, and she hauls them away.
  • Donate your sawdust to schools for use in pottery making classes. Some special firing techniques (e.g., the Raku process) involve packing the pieces in sawdust and firing in a pit.