Football is a game of yards. Basketball is a game of feet. Baseball is a game of inches. And RC is a game of millimeters. The scaled-down nature of RC heightens the need for precision and narrows the margin of error. For that reason, building and tuning an RC vehicle is meticulous, and a matter of a millimeter in either direction can be the difference between a well-tuned machine and a frustrating nightmare. To make precise measurements, well-tooled hobbyists rely on digital calipers, which display measurements on an LCD screen and toggle between metric and standard. There are infinite uses for digital calipers with regards to RC, but here are 10 killer uses that you simply can’t do without.
UNIFORM SHOCK LENGTHS
If one shock, side to side, is longer than the other, almost every aspect of handling will be inconsistent and frustrating. When building shocks, measure the shock lengths when fully extended to ensure that they are uniform on each side. Lengthen and shorten them by tightening or loosening the bottom shock mount.
MEASURING SUSPENSION LINKS
When assembling camber and steering links, setting them to uniform lengths, side to side, is critical. To avoid using a cumbersome setup board, use calipers to measure the suspension links. Both sides of the vehicle links should have the exact same measurements. If one side is off by even a bit, handling and steering will be hugely compromised.
BODY POST THICKNESS
When cutting a new body, it is important that the body post holes are the perfect size: just a bit larger than the body posts themselves. To make perfect post holes, first measure the diameter of the posts themselves, lock the caliper slide, and guide the caliper up the body reamer until it stops. Mark the location with a thin felt-tip marker, and you’ll know just when to stop while reaming the holes.
SCREW AND WASHER SIZES
Any given chassis uses numerous sizes of screws and washers. Their sizes are usually denoted in millimeters. If you get fasteners mixed-up during a build, or need to buy replacements, measuring the dimensions will ensure that you use the correct part in the right place every time.
MAINTENANCE AND STORAGE TIPS
- To avoid corrosion and prevent zeroing errors, always store calipers in the partially opened position, with the slide screw in the “unlocked” position.
- When storing them long-term, remove the battery that powers the display to avoid depleting the cell and developing oxidation in the battery chamber.
- Always keep an extra battery on hand. They are inexpensive, and it never fails–just when you need the calipers most, the battery is out of juice.
- To make recovering your calipers easier after your friend “accidentally” walks away with them, engrave your initials on the bottom of the ruler shaft.
DRILL BIT DIAMETERS
While some drill bits have the size inscribed on the bit itself, some do not. To help organize your toolbox and differentiate between drill bit sizes, calipers can be used to measure the bit diameters. Using the wrong-sized bit can have dire consequences, so knowing their sizes is critical knowledge.
Accurately trimming a new body is more than just aesthetics. If one wheel well is wider than another, or one side is cut higher than the other, the handling and operation may become compromised. When you think the body is “just right,” double check the symmetry of the cuts by measuring with the calipers and comparing from side to side and front to back.
INSPECTING CLUTCH SHOES FOR WEAR
The extreme friction and heat in a nitro vehicle’s clutch system accelerates the wear of clutch components, especially the clutch shoes. During clutch maintenance, measure the clutch shoes. As they wear, they will become smaller. If any are wearing more rapidly than the others, replace them, and if any of them wear by more than about 1mm, they need to be replaced without question.
DIFFERENTIATING BETWEEN SWAYBARS
The thickness of the swaybars determines their rigidity. To determine which swaybars will have more or less flex, measure their diameters. The thicker the swaybars, the more they will counteract body roll and flex, while thinner swaybars will generally improve steering response.
DETERMINING SHOCK PRELOAD
The position of the shock spring collar on the shock body determines the amount of spring pre-load. Like every aspect of shocks, building them accurately side to side is critical. To make sure the preload is even, use calipers to measure the gap from the top of the spring collar to the bottom of the shock cap.
ENGINE COOLING HEAD SHIMS
The shims that separate the top of the piston button and bottom of the cooling head are fickle. The gap that they create affects compression and thus engine performance and consistency of tune. Some head shims are thicker than others, so measuring their thickness is important when buying replacement shims or when engaging in trial and error experiments.
Building an RC vehicle requires extreme precision, and ‘eyeballing’ measurements simply isn’t going to work. Digital calipers allow us to capture and store measurements and build vehicles with utmost care. Although some high-end calipers can fetch over $100, retailers like Harbor Freight offer them for a fraction of the cost and are nearly as precise. Every hobbyist should have digital calipers in their tool-box. They make measuring foolproof and eliminate ineffective guessing work. Just make sure to keep your eye on them, as they are highly thieved in the pits!