Model Research Labs




Your timer is a precision instrument made of an engineering plastic called Delrin with a stainless steel shaft. Its one moving part, a rotor in the timer body, is turned through a viscous medium by elastic, wound on the timer pulley. It is unaffected by moisture or shock and needs no maintenance. Try not to subject your timer to temperatures in excess of 140'F. Don't oil it or let paint or glue seep into its crevices.

INSTALLATION Your Button timer is fixed with a pulley arm retainer that prevents loss of pulley arm should the pulley arm come lose from tapered hub. Wind retainer counter-clockwise off shaft using ring as a handle. Use finger and thumb to pinch pulley straight off hub (see Fig. 1). Now thread retainer on shaft until it bottoms on tapered hub. Note distance of top of shaft

From top of retainer. Now you know how far down to wind retainer when timer is installed in plane. At that point you can clip circle from retainer and trim to taste.

Use tapping screws to mount your Button in chamfered 1/4" hole in 1/8 inch material in plane's nose, pulley on left side for right hand launch, other side for lefties. An unobstructed straight line between pulley arm and pull off lever is desirable. Press DT pulley onto hub.

Your Badge has a fixed pulley and is mounted in a 3/8' hole with two tapping screws.

BUILDING STABILIZER The slant cut elevator in Figure 5 yields a shallow spiral dive allowing light planes to exit thermal better than a straight cut. Make angled cut through stab and coat edges with CA then lightly sand. Cut six hinge strips of hinge material and CA strips into positions 1-6. Pin stab upside down folding each strip through gap and gluing it to opposite side of hinge. A 1/8 inch slightly tapered rod is handy for rolling each strip down and away from the hinge break. It is tricky, practice on something that doesn't matter.

Elevator Adjust Screw Cut and glue balsa doublers for elevator adjust screw fig 5. Then tap a 2-56 hole for nylon screw centered over fuselage.

DT Pull-off lever and Adjustment Pin On the same side as timer pulley about 1/4' back from hinge break, ream an undersized hole for DT pull-off lever (yellow tubing). See Figures 3 and 4. Position and glue 1/4" piece of yellow tubing into hole with about 1/16 inch protruding topside. 1/4 inch is fine for small planes, 1/2or more for larger. See Figure 3 Use enclosed adjustment pin or shaved toothpick to contain elastic, (thread if using spring) in yellow tube Fig. 3. Use a knife to scrape adjustment pin or toothpick so that it snugs elastic against interior tubing wall. Then drill a 1/16-inch hole for the elastic grip, 2 inches or more forward of pull-off lever. Cut a thin slot into backside of hole. Reinforce slot with CA. This slot is the elastic grip.

RIGGING Button Fix a piece of heavy duty thread or light monofilament with a 1 1/2 " loop to the white elastic. (This elastic will outlast a rubber band and provides the long steady pull that gets the most out of your timer.) Springs are custom made stainless blanks big enough to make two timer springs. Stainless springs are relatively unaffected by temperature variations and long lived. When using spring to drive timer an additional spring or piece of elastic is used to lift stab.

Badge Fix a piece of heavy-duty thread or light monofilament with a 1 1/2 inch loop to multi-colored elastic or spring

Adjust length of DT line for adequate tension on stab using enclosed adjustment pin or scraped toothpick to wedge elastic in pull off lever (Fig. 3). Note elastic is continuous from pulley loop to elastic grip. When a spring is used to drive timer an additional spring or elastic is needed to lift stab. You know your set-up is right if your Button Lite clocks about 10 to 15 seconds to pop off when pulley is cranked 90' from DT line, 20-30 seconds for your Button Classic (Fig. 2). Your Badge Lite should have enough tension on DT line to clock about 30 seconds to pop off on 90' test. Sixty seconds for the Badge Classic. With pulley loop free, pull enough tension on stab to lift it smartly to about 45'. Lock elastic in grip.

MIXED INTERVALS Timers, which have gone unused, may run a little longer on the first cycle. If this is the case, stabilize your timer by turning pulley one half turn then calibrate with the 900 test. Use the same interval each time you calibrate your timer using the 90' to pop off test.

Then, with a stop watch and your desired intervals in mind, crank, release and time pulley arm to "pop-off' until you have identified the desired intervals with an alignment mark on the plane (Fig 2).

Your timer's fluidic heart though relatively insensitive to temperature variations, does run faster as temperature increases. This combined with the elastic's tendency to wimp out through time urges us to stabilize and calibrate before each flying session. Stabilizing and calibrating are essential to the honoring of indexed intervals.

We recommend you not run timers with less than I oz tension on elastic at the pulley. If more time is needed you can double wind timers by passing pulley arm through loop after the initial wind. WHEELS & WINGS P.O. Box 762; Lafayette, CA 94549-0762

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