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....
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 vise) 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. Such a poor man's lathe is 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.
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...
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......... "
And one final thought from your editor.
I personally find that a Dremel turns the potentially out of balance rough wheel blank too fast for comfort. I have seen things get ugly in a hurry when the 1/16 soft aluminum tube bends. Instead, I chuck the axle in my hand held cordless drill and use the dremel tool spinning a coarse sanding drum to do the rough shaping. Turning the wheel more slowly helps prevent any out of balance issues from becoming scary and sneaking up on it with the sanding drum allows rapid material removal. Once I have the desired shape, I smooth the wheel with fine sandpaper.
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