F/FSport P
ut your best foot Wheeling and dealing
Ed has been using foam to replace sheet balsa on his models. Note that if you’re building to the rules of the Flying Aces Club, the use of foam is limited to “add on” parts such as air scoops, radiators, guns, tail cones, and the like; and engine cowls up to the firewall. In particular, he likes to use black foam grocery packaging for light- weight wheels which is okay by the FAC. He starts by cutting oversized, roundish blanks from the tray. A single layer is good if you need a thin tire, or glue several layers together if you need a “balloon” tire. White glue works well, but be sure to let it dry thoroughly! Foam does not really absorb the moisture in glue, so it takes a long time to set. Patience, Grasshopper. Drill a 3
⁄32 -inch
hole through the center of the foam blank. Make sure the blank is plenty oversized. Now insert a small #4 machine screw through the hole in the blank and thread a nut onto the screw. Tighten until the screw head and nut slightly indent the foam. Then thread a jam nut against the first nut. Hand tight is good.
Insert the exposed end of the machine screw into a Dremel tool or variable speed hand drill and mount lightly into a vise, or clamp to a workbench. Square up the wheel using a very light touch with wood turning tools, a good knife, or 120-grit sandpaper mounted to a hard block. Use a very, very light touch! Experiment with the speed—Ed says slow works best for him.
Carefully bring the diameter to the size required, measuring so you get consistent
by david mitchell You can reach David Mitchellat 230 Walnut St. NW, Washington, District of Columbia 20012, or via e-mail at
davedge@me.com forward. You
wouldn’t wear a pair of flip flops with your best suit would you? Naw, of course not. So, you’ve spent a lot of time on that spiffy new scale model of yours, put some great wheels on it! This month we’ll take a look at the feet of the model. First off, Ed McGugan of Lucknow, Ontario sent me some pictures of his method for making foam wheels. He also sent me great comments—my favorite kind of sub- mission! I’ll just put his text in the blender with mine, and hey presto…instant copy!
PHOTO: ED MCGUGAN
With the foam blank chucked into his Dremel, Ed McGugan uses a sharp turning tool to bring the wheel into a pleasing round shape.
results. Then round the corners of the tires using small bevel cuts. You can also under- cut toward the “wheel hub” for an authentic appearance. After the main shaping is com- pleted, use the finest sandpaper you have with a very light touch to blend the shape. A flexible strip works well as the maximum pressure you can apply is the bending strength of the sandpaper. The very lightest and briefest touch you can manage is enough to do the job. The point of a knife or turning tool can then be used to add “tread” grooves. Five to seven grooves look nice. Just a touch works to groove the foam. Remove the screw from the wheel and clean up the hub area. Finally, glue in a small length of 3
⁄32 -inch o.d. aluminum tube.
This will work best if you rough the outside of the tube up a bit with sandpaper. Placing a pin through the tube into your building board and eyeballing the “verticalness” of the pin works fine for our purposes. Use two concentric aluminum tubes to get the inside diameter down to a nice fit on the wire land- ing gear.
Alternately, rather than using the ma- chine screw method outlined above, you could glue a length of aluminum or brass tube, roughed up with sandpaper, into the foam blank and insert the tube into the chuck of the Dremel. Proceed as above to turn a very true running wheel—sandpaper
rather than cutting tools is probably your best bet here.
Again, you must allow plenty of time for the glue to set for this method to work well. Ideally you will be able to wait a couple of days. Otherwise, the wheel will break free of the tubing while you are turning it—the larger the diameter of the wheel, the greater the risk.
To keep the jaws of the chuck from crush- ing the tubing, fit the appropriate size music wire into the tubing first. Leave this wire in the tubing while you are trimming off the ex- cess tube after the wheel is turned. Ed re- ports his wheel technique has worked for wheels from about 1
⁄2 to 1 inch in diameter,
and would surely work for other sizes as well. I’d like to add a couple of ideas to his method, though they are not shown in the pictures. If you capture your foam blank be- tween a couple of washers in addition to the nuts, your ability to clamp and securely hold the foam is increased. If you can find wash- ers of the same diameter as your desired wheel “hub”, you can use the edges of the washers to help define the outline of the hub when you are profiling the wheel. Failing that, you can use a cutting com- pass to make your own custom “washers” out of flat 1
⁄16 plywood, which will work just
as well as metal flat washers. If you find or make washers of the same diameter as the
PHOTOS: ED MCGUGAN
Ed creates tread lines in the wheel with a thin, sharp pointed tool. Note the wheel blanks in the background (above), ready to be threaded onto the machine screw mandrel and chucked into the Dremel. A view (at right) of a finished wheel, showing how the wheel blank is held in place against the head of the machine screw with two nuts.
50 JUNE 2014
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