Sim's RC Tips and Tricks

THE INSTANT PLASTIC TRICK
I've found a good way to fill holes in stiff plastic parts pretty easily. First, find a place with a good ventilation so you don't inhale too much toxic fumes. Mix equal parts liquid CA or superglue (the watery stuff works best) with talcum powder in a small bottle cap (throw this away later as CA is very poisonous) and use a small toothpick to apply it to the hole you want to fill. Work fast as this stuff dries in less than a minute. After it dries, you can file it, drill it and tap it for screw threads. To fill bigger holes, I usually tape up the bottom with some masking tape and fill it to the brim. This stuff is great for the fill, drill and tap method to fix the stripped screw threads on your plastic chassis cars. I prefer it over epoxy because it has great consistency and it cures in seconds so I can resume working on the trucks almost instantly. I learnt about this stuff from an old plastic model builder's web site which no longer exists but have found it immensely useful in RC. And my wife thinks I'm crazy to stock up on cheap superglue.

THE GRUB SCREW CADDY
I managed to beg for a few extra grub screws off the LHS and needed a way to store them safely. I'm sure you know what would happen if I just said I'll keep them in one of the parts box compartments and be careful not to lose them.

So, here's what I did instead: I got a small block of plastic (wood would work too, but I used a bit of kitchen cutting board leftover from one of my projects) and drilled 2.5mm holes into them. I widened the openings of the holes slightly with a knife and screwed the grub screws in. No more keeping them inside little folded plastic bags.

WIND YOUR OWN (SLOW) MOTOR

Every one in awhile, I actually do want a slow motor in a rig (say, for rockcrawling or when my wife is driving). I've tried looking for something slower than 35-turns in Malaysia. Basically it doesn't exist. Everybody here is a racer and when I go into a LHS to tell the owner I want a slow motor, he looks at me like I just asked to have my legs amputated, then ushers me towards a 17-turn modified and gives me a nice speech on why I should repent my slow-driving ways.

So... I did the only thing any self-respecting scratch-builder would have done and wound my own 40-turn out of some copper wire. The armature on the right is my homebrew 40 turn single. Not sure what gauge wire I used, but it's enamel-coated and a lot thinner than the wire on 23 turn armatures like the one shown here on the left. All I know about rewiring motors, I learnt from this thread on rccrawler.com. Thanks, John!
Edit: I later epoxied down the copper wires and ground away parts of the stators to balance the armature.

The original motor was a 23 turn Yokomo T-max stock motor. A notch on the endbell sits on a slot on the can to lock the motor at 24 degrees advanced timing but since the car will need to do a fair amount of reversing, I cut a new slot with a Dremel cutting disk (Goggles On!) to bring the timing back to zero. I got it wrong a bit at first and got in about 1 degree of backwards timing. I spun the can 180 degrees and cut a new slot (shown here), but that made the motor spin in reverse. Rewiring the motor leads fixed that.

(WARNING: It's a lot easier to wind a high-turn slow motor, so I cannot recommend trying to wind your own low-turn fast motor because they would need to be more accurately balanced to remain stable at high RPM's. In fact, wind any motor at your own risk. Mistakes could lead to setting your motor, battery, speed controller, receiver, servo, car, house and/or self on fire. Also, tempering with the motor armatures could lead to void of warrantees.)

SOLDERING DEAN PLUGS

I never look forward to soldering wires to Dean plugs. The pesky little things never stay in one place when I press the wires or soldering iron against them. I find that it helps a lot if I plug in the other half of the pair of plugs and hang on to the far end with the third hand tool (or a pair of alligator clips pressed against some Blue Tack). The other plug also helps to dissipate the heat from the one you are trying to solder so it doesn't melt the plug as easily.

HOMEMADE SCREW TAP

If you need to tap some screw holes into plastic or aluminium, the best thing to use is a screw tap. If you don't have one handy, you can make one out of a steel cap screw. Just use a very thin rotary tool cutting wheel and cut a groove along the screw and that's it - you now have a cool new tool to tap screw threads with. Make sure the screw head or bolt head is strong enough. Here I'm using a mild steel M3 bolt with a 2.5mm Allen hex head which is plenty strong for threading plastic and aluminium.

MOTOR BOX

When you buy a Tamiya motor, it comes with a nice box with a cardboard insert inside to act as a cushion for the motor. Without the cardboard insert, the box is just the right size to hold 2 motors, saving you some space in your pit box. You will to cut out some styrofoam or similar material to keep the motors sitting snugly in the box though.

DUSTPROOF RECEIVERS

I've tried all sorts of ways to keep dust out of my off-road receivers. In a nitro car, it's easy to keep it inside a balloon and a receiver box but in an electric car, there's usually not enough space for a receiver box, and a balloon makes frequency crystal changes difficult. Most of the dirt goes into the receiver through the servo leads, so I tried plugging up these places with soft foam (the same type that's used to keep the dirt out of ball joints) and so far, it's been working very well. Just cut a piece of foam a little bigger than the servo socket holes, stuff it inside and push it all the way in with servo plugs.