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How to: Body trimming tips & tricks

How to: Body trimming tips & tricks

Bottin, Stan

Learn to lop off Lexan the right way!

It’s very difficult to truly screw up an RC kit; if you make a mistake, you can always disassemble the parts, go back a step or two and make things right. Trimming the body, however, is a completely different story; once you begin to scribe and cut, you’re committed. The keys to doing the job right could be summed up as the “three Ts”: tools, technique and time. When you have the right implements, know how to use them and take your time, you’ll be able to trim any body easily. Heck, you might even enjoy it.

The tools

* Hobby knife. Most of us refer to this as an “X-Acto; which Is the most-recognized brand name. Excel makes nice hobby knives, too. Go for a pencil-type knife; I like the type with a rubber coating on the barrel that gives you better grip.

No. 11 blades. Your hobby knife came with at least one blade; some are sold in sets with 15 blades. If you buy a new knife, go for the 15-blade option; you’ll have to

replace the blades often. Already got the knife? Spend a little extra now but save In the not-too-long run by going for the 100-blade box. Stick with the no. 11-blade; it’s best for body-trimming needs.

* Circle cutter. This is basically a compass with a blade Instead of a pencil. OLFA and Niftech offer similar units. When you have to cut cooling holes or make large-radius rounded corners, a circle cutter Is the only way to go.

* Metal straightedge. A metal ruler makes a fine straightedge. Don’t use a plastic ruler; your hobby knife will dig Into it and stall your cut. Plastic rulers are OK for drawing lines with a marker, but they aren’t a good choice when cutting. A section of aluminum “L” or “T”-channel from your local hardware store also makes a great straightedge and Is easier to hold than a flat ruler.

* Reamer. Reamers are used to make small holes (less than 1/2 inch in diameter), and the two basic types are the classic fluted style and the latest “knife-edge” reamers. Hudy was the first to offer the knifeedge style, and It Is now copied by many other brands. This type of reamer makes very clean holes, but It cuts very quickly; If you aren’t careful, It’s easy to make a hole too big. A fluted reamer is easier to control but tends to leave a thin lip of material around the hole; this is easily trimmed away with a hobby knife. Fluted reamers are also generally less expensive than the knife-edge types.

* Curved-blade and straight-blade scissors. DuraTrax, Trinity, OFNA and Kyosho are just a few of the brands that offer curved-blade scissors known as “body scissors: Their short, curved blades make It much easier to cut rounded corners and snip out fender wells. A pair of short-blade conventional scissors Is also good to keep handy so you can trim short sections of the body that require a straight cut.

* Avoid the nibbles. When you cut fender wells with body scissors, you may find that the tips of the scissors leave “nibble marks” In the paint or on the outside of the body, especially if the body’s hood or rear deck is very close to the tops of the fender wells. To avoid this, put a layer of masking tape over the body fender well area before you cut it.

* Wheel openings with a circle cutter. A circle cutter is the Ideal tool for making perfectly round wheel openings, but only If you can find the center of the wheel opening. If you want to mount an oval- or touring-car body that has molded-in front fender wells but no rear fender well positions, first place the body over the chassis and line up the front wheels In the front fender wells. Next, use a marker to make a dot over each axle’s center; they mark the centers of the wheel openings. If you have an HPI body, you can skip all that; the wheel-well centers are conveniently marked with dimples-made with a circle cutter In mind. After youVe marked the centers, trim the wheel openings; use the technique described In “Making Holes.”

Straight lines made simple

* Rocker panels. Touring- and oval-car bodies have a long stretch of rocker panel between the wheel openings that is almost impossible to cut perfectly straight with a pair of scissors. A straightedge and hobby knife work best, but It can be difficult to hold a straightedge on a flexy body and cut It at the same time. The solution Is to support the body on the corner of your bench, or, better yet, clamp a piece of scrap wood to your bench as shown; now you’ll be able to press the straightedge down firmly for a perfect cut.

* Air dams and rear bumpers. You can use the rocker-panel technique to cut the long straight sections of the air dam and rear bumper, but cutting a straight line around the corner of the body to the quarter panels can be difficult. To make a perfect cut, use masking or electrical tape to Indicate the path the knife should follow, then carefully make the cut by hand, using the edge of the tape as a guide.

Making holes

* Body-post holes. You could use a drill for this, but that’s a lot of tool for a little job; use the reamer instead. Some reamers have a sharp tip to pierce the body, but most work better If you first make a small pilot hole. Just twirl the tip of your hobby knife Into the Lexan body until it breaks through, and use the reamer to open the hole. Don’t go crazy; check the hole’s fit on the body post frequently so you don’t make it too big and end up with a loosely fitting body.

* Cooling holes. If you race under ROAR rules, cooling holes can be no larger than 2 inches in diameter. Set your circle cutter so that the pivot point and blade are 1 Inch apart; this will give you a 2-inch circular opening. Gently press the pointed pivot leg of the circle cutter into the body where you want the center of the hole to be. You don’t have to pierce the body; just press the point down firmly enough to prevent it from sliding. Next, apply light pressure to the blade end and smoothly swing the cutter around to score a complete circle. Make only one pass; multiple passes may cause the blade to wander. To remove the disc of waste material, open the center of the hole with your reamer, use body scissors to cut out to the edge of the hole, then flex the Lexan to crack at the score line; peel out the waste, leaving a perfectly round opening.

* Special shapes. Not worried about ROAR rules? Feel free to make more Interesting shapes for the cooling holes. No matter what shape you cut, the technique is the same. After you’ve made an outline, use a reamer to make holes In the corner of the shape, then score between the holes to join them. Make a hole in the center of the shape, cut out to the holes In the corners, then pop out the waste pieces. For perfect slots, just join a pair of holes with scored lines and peel out the piece of Lexan from in between the holes.

Copyright Air Age Publishing Oct 2002

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