From: Tom Sanders
In creating balsa wheels, you must set the parameters for their use. Are these for a lightweight indoor model or for a larger, outdoor flyer? The process is similar just that the bigger, outdoor wheels require some added attention. Let me disclaim that none of these ideas are unique. Some of these ideas can be mixed and matched to your requirements. Accumulating various tools such as a Dremel or Dremel sander will certainly help....
Dremel or electric hand drill
drill bits (1/16" and less)
a/c ply - 1/64", 1/32" and 1/16" thicknesses
balsa stock, 1/32" sheet and thicker
tubes (alum. or plastic)
various X-acto knife tips
water based enamels
The simplest wheel to make starts by choosing some 1/32" sheet stock. Depending on diameter cut out some squares, a little oversized, and glue together. Be sure to CROSSGRAIN the squares when you stick them together. Your flavor of glue doesn't matter unless you want to be weight conscious. Acetate is the lightest, CA is next and aliphatic is a distant 3rd.
First, decide what you want for your axle bushing. You may choose 1/16 aluminium tube or, my favorite, those little red plastic straws from aerosol spray lubes. In fact, I have collected many of those red straws as the I.D. varies between manufacturers. Sand a taper into the end of the tube and bore an undersized hole (with your pin vice) into both squares. Rough up the tube's surface with some 400 grit wet or dry paper. Poke the tube through the squares always leaving about a 1" separation. Put the glue (aliphatic is the best for this!) on the tube surface and slide the squares into the glue. Be sure there is plenty of tube length to chuck into your drill or Dremel. Roll the axle and "true" each wheel to prevent wobble. Let them dry for 24 hours!
The easy way to finish is to simply chuck them in your drill and very patiently sand them round with a sanding block that has 400 grit affixed to it. Don't bear down to hard or the glue joint will part company.
To further slow down your turning tools to keep the tube from whipping you'll need to reduce electrical current... With the Dremel, and especially those without the speed adjustment, make a speed control box with a rheostat and an old extension cord. Buy a quality wall switch (dining room style) for the rheostat control. Split the cord, laterally, and cut one side only to make an in-line connection with the switch. Wire the connections to the rheostat. Now, plug in your Dremel and keep the speed low enough not to "whip" the tube into a 90 degree bend.
Some folks make a fixture to hold their Dremel with a hose clamp on a wood block screwed into some plywood. Poor man's lathe, but very effective! Go back to sanding the outside wheel diameters, measuring as you go. To separate the wheels, you can try cutting them with a razor saw. Or, cut a piece of hardwood narrow enough to fit between the wheels and use as a cutting board. Put your X-acto #11 against the bushing tube and roll it back and forth until it cuts through. File each bushing so that the ends are smooth. Leave about 1/16" on both sides of the wheel.
For smoother airflow, taper sand the wheel from the bushing center out to wheel's O.D. This will track the wheel cleanly through the air as the model flies. Thin wheels will act as airbrakes if there's no taper.
The basic wheel is finished.
The bigger wheels use the same idea but .... bigger.
Use the same sandwich concept with thicker balsa but add the a/c ply as a center layer. After the tube is inserted, turn in the same manner. Leave enough room between the two wheels so that when they are separated, they may be chucked from either side. Use the emery boards to create the curved part of the tire. Experiment with emery boards, files, whatever to shape the depression that a hubcap would fit over. You can also groove in tire tread with an X-acto while the wheel is chucked on the drill/Dremel. This all takes practice but the results will be stunning.
Leave the wheel chucked so that it may be rotated by hand. Dip your brush into the flat black and brace the brush. Rotate the wheel while the first circle is painted. Some folks use a SHARPIE Ultra-Fine pen for this job. After that it's easy. Black on the outside, your hubcap or silver brake disc on the inside diameter. Mount the wheel on axle and cautiously layer a growing dab of glue to retain the wheel on the axle.
By the way, even lighter wheels can be made using pink or blue insulation foam with durability slightly compromised. Same process but use aliphatic (white glue) on all assemblies.
There are more to the details but I have run off enough for now!
Fellow FFML'er Marty Sazaki comments...
"Good article. I'll make one suggestion though. Don't start out with a square. Get as close as you can to the circle you want before you put it in the chuck and do the shaping. It will be a lot less stressful all around that way."
Tom responds with, "You're right about starting your wheel as a circle. That was one of the many "additionals" I thought about but edited out. Others were using spent bullet casings with ground sharp edges to put in lightening holes. Or, how about using a rubber o-ring as a tire, worked great on my Flying Aces Moth. What about paper cone wheels?
Here's what you do......... "
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