Build a Bicycle-Powered Band Saw

With our bicycle-powered band saw, you can take your bicycle out of winter storage and put it to use.
By William Kolberg
May/June 1985
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Except for the "drive motor," my bicycle-powered band saw is similar to any standing band saw. No alterations to the bicycle are necessary, and it takes only a minute to switch from riding to sawing mode.

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I'm a carpenter, and for years I assumed that the best way to cut wood was to plug in and "go with the flow." For small jobs I'd still use my trusty handsaw, but for long, straight cuts I'd grab my two-horsepower circular saw and seek the nearest three-prong outlet.

That was OK when I was at a contract job site, but when I was working at home — especially through our mean, lean Wisconsin winters — it seemed as if a goodly share of my profits was being metered away to the local utility company while I was left with the crumbs.

And, of course, the cold season also kept me from my favorite pastime, bicycling. So, in order to fit one solution to these two seemingly disparate problems, I researched — then built — my "bandcycle" ... a bicycle-powered band saw that makes accurate crosscuts, rip cuts, and miter cuts through soft- and hard-wood, and — with a simple blade change — saws through mild steel and aluminum as well!

Because the tool is made almost exclusively of common materials and salvaged bicycle parts, it cost me a good deal less than a commercial model with similar features. And though I'm not about to claim that it's as convenient or powerful as an electric saw, it's a heck of a lot cheaper — and even sort of fun — to operate.

Band Saw Basics

I didn't reinvent the wheel when I pieced together my bandcycle. In fact, I just patterned my design after a conventional band saw. Typically, the lower wheel is held rigidly on its axis, while the upper wheel axle can be tilted a few degrees from horizontal to keep the blade from wandering off the rim.

That toothed steel band passes through a slotted table and is held in line by two guides, which keep the blade in position when it makes long, straight cuts and also prevent it from twisting on a curved slice. In addition, the guide above the table is adjustable to accommodate various thicknesses of stock, and both guides incorporate a thrust roller that runs against the back of the blade to keep it from being pushed off the wheels under pressure. Finally, band saw wheels are usually fitted with flat rubber tires to protect the set in the teeth and to prevent blade slippage.

So, the only significant differences between any old band saw and my cycle saw are these: [1] I've done away with the drive motor, and [2] I've added a set of brackets to hold the rear wheel of my three-speed firmly against the lower wheel of the saw.

A Material Matter

To construct your own pedal-powered version of my invention, take a look at the Assembly Diagram and Materials List and begin gathering the necessary parts. When scrounging for the 24" pipe that will serve as the various bracket collars, make sure it slides easily — but not too loosely — over a sample piece of the 1" tubing that's to be used for the saw's frame; a good fit here will assure an accurate cut later on. (While 1 1/4" iron pipe will come close, it's not the best choice. Try to find some chain link fence rail or mechanical tubing like that used on scaffolding or implement frames.)

Also, be certain the wheel assemblies you choose are fully spoked and straight. Though you could probably buy the flat rubber tires for the rims at an industrial supply company, you can make do by stretching sliced sections of truck inner tube over the wheels or even using a couple of bike rim strips to make rubber "pads" for each wheel.

At $26 a pair, commercially made blade guides might be a bit pricey for your budget, but you can make your own, using the instructions I'll provide later. As for the blade, you're going to have to buy that, so pick something that'll handle general woodcutting chores to start — a 3/4" x 14' band with 4 or 6 teeth per inch suits my needs. (A saw-sharpening shop should be able to fix you up, but double-check the blade length required by your tool before you put down your money.)

A Fitting Proposition

The biggest part of the bandcycle is the tubular frame. Buy or borrow a conduit bender with a 1" jaw capacity and do your best to form two identical elongated S-shaped members. Again, refer to the Assembly Diagram. Ideally, the uprights should be nearly 6' long, the legs 15" in length, and the horizontals 12" between bends.

With the frame formed, drill a series of holes in the outside of each upright, starting about 4" from what will be the top end. File these to create elongated adjustment slots in the tubing. Next, cut part of your scrounged 2' collar pipe into four 3" lengths and weld them (or have them welded) to the legs of each conduit upright so they'll protrude perpendicularly from the same side the slots are in. Drill two 1/4" holes — parallel to the uprights and about 2" apart — through each piece, and, using one of the bike wheels as a spacing guide, fasten the frame members to the center of a 3/4" x 21" x 30" section of plywood with 1/4" x 2 1/2" carriage bolts.

Next, you can tackle the collars that hold the axle brackets, blade guides, and table supports to the frame. Cut the remaining 12" of collar pipe into eight 1 1/2" lengths, and weld a 1/8" x 1 1/2" x 2" tab to one side of each collar. Then drill and saw 3/8" x 1 1/4" slots into four of the collar tabs (clamp them together to form pairs, then cut one set vertically and the other set horizontally).

Now take the four unslotted collar assemblies and the two horizontally slotted ones and weld 1/8" x 1/2" x 1 1/2" strips to their sides. By drilling two 13/64" holes through each of these built-up areas and threading them with a 1/4-20 tap, you'll be able to place 1/4" x 1/2" hexsocket set screws into the holes and use them to lock the collars into position on the tubular frame uprights.

The remaining vertically slotted collars get a different treatment, but all it involves is drilling a 1/4" hole through the outside of the collars and bending each of a pair of 1/4" x 6" threaded rods into an L shape. The shorter part of each L will pass through its frame slot and collar hole to be held with a nut, while the longer shaft will protrude through the top of the frame and be drawn upward with a nut pushing against a flat washer.

To finish up, you'll need to weld the 1/8" x 1 1/2" x 14" table supports to the tabs on two of the tapped collars, then bolt the 1/8" x 1 1/2" x 2" angle iron brackets to the ends of these supports. Also, after installing the lower axle brackets and slipping the wheel in place, you'll have to determine the exact length of the 1/8" x 1 1/2" blade guide support by lining it up with the recess in the rim. Be prepared to make some minor adjustments to suit your particular blade guides; the manufactured type will require a 3/4" x 1 1/2" shoulder at the tip.

If you want to make your own blade guides, you can do so easily, using a 4" length of 1/8" X 1" angle iron, a 1/8" x 1" x 1 3/4" piece of flat stock, four No. 10 x 1/2" machine screws, a 1/4" x 1" bolt with two nuts and three washers, and a 1/2"-bore, 1 1/8" OD (No. Z99R8) sealed bearing.

Cut a 1" section from the angle and drill two slotted mounting holes through one side of it. Bolt it against the face of the remaining piece at one end, then fasten the hunk of flat stock in line with the protruding side of the 1" angle. Mount the bearing just above these two flat "fingers," allowing it to ride on a 1/4" nut threaded against a washer and the bolt head. Then trim the lateral guides so they don't disturb the set of the blade teeth, adjust the gap to suit its width, and bolt the assemblies to the guide supports.

While the rim's still in place, determine the proper position for the 1/8" x 2" x 3" axle brackets that'll support your bicycle's rear wheel. Hold your bike tire up against the rim and mark where the axle falls on the saw frame's horizontals. Make 3/8" x 2" slots in the bracket plates and weld them with their midpoints over the marks.

Finally, cut the 18" x 18" table from your remaining piece of 3/4" plywood and position it for mounting. Remember to slice a groove in the board to accommodate the blade. Once you've gotten the proper length band, place it around the wheels — with the teeth nearest the table pointing downward — and tighten the lower axle. Draw the upper adjustment shafts upward as necessary to make the blade "track" near the center of the rim.

To lock your bike to the frame, let some air out of the rear tire and press it against the blade with its axle in the brackets. Tighten the axle nuts and fill the tire until you achieve good traction, then just let 'er rip!

The pedaling half of your team should maintain a steady, even pace while the cutter guides the stock into the blade. Intense bursts of pedal speed won't cut the wood any faster, and feeding the wood too fast will just bog down the "motor." Sixty revolutions per minute at the pedals (a reasonable cruising rate) moves an impressive 1,025 feet of blade through your work every minute, enough to slice any board.

About the only low-buck improvement that I could suggest for the bandcycle is the addition of a flywheel, which I incorporated right into the lower wheel a few months after building the saw. The added mass discourages bogging, smooths out the cut, and in general makes this unique tool nearly as practical as its current-hungry cousin!

One Good Turn Deserves Another

A flywheel is a simple rotary device used to store kinetic energy. Its mass, once set in motion, has enough inertia to continue that motion at a fairly steady rate. If mass — in the form of concrete — is added to one of the bandcycle's wheels, the moving blade will be more resistant to velocity changes brought about by knots or dense grain, and thus won't snag or bog.

To make the flywheel, simply lace about 15 feet of baling wire through the spokes of your truer wheel. Distribute the wire evenly and wrap it around the spokes, crossing from right to left sides at various places to create a network within the wheel that will support the concrete disk.

Next, cut a sheet of cardboard to the exact diameter of your rim, pierce its center to accommodate the axle and hub shoulder, and use some duct tape to seal the perimeter of the cardboard circle tightly to the edge of the rim. Now coat the exposed axle and hub shoulder surfaces with grease or petroleum jelly to protect the threads and bearings.

Set the wheel, cardboard down, onto an old car tire, and prepare to mix your mud. I found that a 60-pound bag of pre-blended mortar mix was just about perfect for the job. Be sure to wear rubber gloves throughout the casting process, or you'll learn, as I did, that the highly alkaline cement will damage your skin.

Add water slowly to the mix to achieve the perfect consistency — one that flows slowly and easily and that can be formed with a trowel or straightedge. Scoop the batter gently into the mold, and use a stick to dislodge and fill any hidden air pockets. Once the wheel is "topped off, " smooth the mortar with a straightedge and scrape away any excess, being careful to use the rim edge as a guide to avoid exposing the spokes.

The concrete will take from one day to a week to cure, depending upon the temperature. In hot climates, you may have to mist the casting occasionally to keep it moist, while a freezing environment will require that you cover the mortar with plastic and a thick layer of straw. Once it's set, you can bolt it to the bandcycle's lower bracket and start throwing your weight around!

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