Servo Tester

Description

This is a device I made to test and setup servos for my RC airplanes. My most recent build was a sailplane with V-tail and spoiler. The servo setup got quite complex. Each ruddervator servo had inputs from both the rudder control and the elevator control. The ruddeer stick required nearly twice the response on the ruddervator as the elevator stick. In addition I wanted dual rates and expo. When the spoiler is activated I needed to mix in some up elevator to offset the loss of lift. Before installing the servos into the sailplane I wanted to be sure everything was working the way I envisioned. I tried hooking up the servos and receiver just laying loose on my desk but found it was hard to get a good feel for exactly how much a servo was responding to a transmitter stick movement. This thing allows me to measure the servo response in degrees. There are 2 different versions. One uses rubber bands to hold the servo while the other uses a pair of bolts. Other than that they do the same job equally well. I have tried to design it to accommodate various size servos. The ones shown are fairly small KST 80 series servos. I have tried larger servos with good results. For the rubber band version you need to print the rubber band base, dial (degree scale) and one knob. For the bolt down you will need the bolt base, dial and three knobs. A piece of self stick foam from an art supply store is stuck to the base to keep the servo from sliding around. It appears as a black patch under the servos in the pictures. You will need a 3M x 12mm screw and nut to hold the degree scale (dial) to the base. If you use the base with the bolt hold downs you will also need 2 hold down bolts 3M X 30mm with 4 nuts. The nuts should press fit into the knobs. I have included a pdf you can use to print out the degree scale. I have included a smaller version and a larger version of the scale so you can make a smaller or larger version by scaling the stl. The .stl files supplied will match the middle size degree scale. After printing the pdf cut out the degree scale and then cut off and discard the bottom half. I attached the scale to the tester with spray contact cement. To use, remove the degree scale and attach the servo with the output gear centered in the base cutout. Next slide the degree scale on to the base so the bottom of the scale aligns with the middle of the servo output shaft and tighten the degree scale. The alignment does not have to be exact. I just position the servo by eye and it gives good results. Now attach a servo arm and you are ready to check out your servo.

Statistics

Category

Tags