In the box, you will find two longer 1”x 4” pieces and one shorter 2 x 4. Assemble the two longer uprights to the shorter with the supplied (taper base) wood screws. Place the shorter base piece on a hard flat surface and fit the uprights to the narrow side (2”) of the base. The base piece should have the longer piece extending out to the sides to make the base stand steady as shown in the picture. The uprights should be parallel to each other. If they are not, adjust them before installing the screws. The holes are pre-drilled, and the screws started. To make the assembly stronger, it is recommended that wood glue be applied to the joints. Finish, such as varnish, can also be added if desired.
Make sure the assembly is placed on a hard flat surface. It is suggested a weight be placed on the bottom piece to hold the assembly motionless while making the adjustments. Use a carpenter’s level to adjust each spindle beam (the angle aluminum on top of each upright) until it is perfectly level. To level, insert a shim under the low side until the beam is level.
Your kit is supplied with a 1” and ¾” diameter spindle shaft. One inch is commonly used on wood props and ¾” for carbon fiber. Slide the spindle into the center hole of your prop. If it will not fit, enlarge the hole using a wood boring bit or sandpaper. If you have a carbon fiber prop, use a metal drill bit (not wood boring) of the appropriate size, usually ¾”, or use sand paper. If the spindle is loose, add a little masking tape to the spindle to achieve a tight fit. When adding masking tape, make one wrap then cut the tape so the ends do not overlap. Fit the spindle into the prop hole until there is an equal amount protruding on each side of the prop.
Balancing Wood Props
Place the prop with spindle tube installed on top of the uprights. If one tip is heavier, it will rotate to the bottom. The other tip (the one pointing at the ceiling) will need weight added to bring it into balance. Select a piece of lead and tape it to the prop about 4” from the tip. Move it back and forth until the prop rotates to the level position. More or less lead maybe needed to get the balance point. Drill a hole, usually 3/8” or greater, at the spot where the lead is taped. Be careful not to drill all the way through the prop. Melt the lead and pour it into the hole. To melt lead, use a propane torch and a metal cup. If you don’t have the means to melt lead, use .177 or .22 caliber lead from a pellet gun. Pound the pellets into the hole to flatten them out and secure with five-minute epoxy.
Now, rotate the prop 180 degrees so the tips are now on opposite sides. If the hub is out of balance, the prop will rotate until the heavy side of the hub is at the bottom. Tape a sizeable piece of lead to the top of the hub at the center. Add or subtract weight until the prop will sit level. This is a time consuming and often frustrating process (Budweiser or your favorite brew will help ease the agony). Rotate 180 degrees to ensure it will still balance in the original position. When you are done, the prop will be balanced on both planes and will run smooth as silk.
Balancing Carbon Fiber Props
The method used to balance a carbon fiber prop is the same as for wood, except the weight is only added to the very tip of the prop and less is needed, as the prop is a lot lighter. It may only be necessary to paint the light tip to get it to balance.
To add weight a small hole, about ¼”, is drilled at the tip of the light end. After adding the correct amount of weight, fill the remainder of the hole with sawdust mixed with five-minute epoxy. You have to be careful with this step or the prop will end up out of balance again.
I usually add lead until the weighted end is not quite level (a little light). When the epoxy mix is added to close the hole, the prop will balance. I put a piece of tape over the epoxy so when it sets, it will be nice and smooth and will hardly need any sanding. Epoxy does not need air to dry, as it is a chemical reaction.
It takes practice to get it right the first time. If you do end up heavy on the tip after closing the hole, add a little more paint to the opposite tip to get it back in balance. Remember the paint will get lighter as it dries, so check the balance again after the paint has completely dried.
Use the same method to balance the hub as for wood props. Be careful to only drill near the center of hub. This can be tricky with puzzle props.
Three Blade Carbon Fiber Props
Assemble the prop, install the spindle, and set it on the balance beams. One blade will rotate to the bottom. Rotate the prop until you’re certain the heavy blade is identified. The other two blades will need to be balanced to the heaviest.
Tape weight to the tip of the blade next to the heavy one. Add weight until the top blade is pointing straight up. So far this is easy, but just wait. Rotate the top blade to the bottom and add weight to it until the blade on top is pointing exactly straight up. You’ve got it right when any blade rotated to the top position will remain pointing straight up.
Drill holes at the very tip to add the lead weights. I usually use the lead pellets, as it doesn’t take much weight. Add the epoxy sawdust mixture to close the hole. For three-blade props, this is the only step, thankfully, needed to balance them. Number the blades near the hub as 1, 2, and 3 using a sharp scribe or engraving tool. If you take the prop off, reassemble in order so the balance will not change.