1/2A Prop Balancing
Prop Balancer Rework , came about to trim out those lightweight carbon props. My current carbon 1/2A props weigh in at 2.4 gm, tough job on any of the popular balancers available. I could just design a new one or, take the best of what's available, the TF Magnetic Balancer and modify it. The problem with the curent version is the mass of the shaft and cones, 9.5 gm, 4 1/2 times the object your balancing. The new shaft and bushing weighs 2.1 gm. The bushing OD is turned to acheive a tight fit, in my case, 5mm, the prop ID. and drilled with a .061 hole. The shaft is 1/16 straight music wire 3 1/2" long, grind chamfed ends. Taper one end of the shaft with sandpaper so the bushing slides up about 1" and stops.  Make a balsa botton from 3/8" and cap one end with 1/64th ply and stick mylar tape on the ply.
  Assemble as shown in photo below. Use double stick tape to position the block, place low on the magnet. The idea behind the mod is to limit the amount of magnetic pull, seperating the shaft from the magmetic pull should make it more responsive to an unbalanced condition. Adjust the mag distances to get the most effective reaction based on the weight of the prop, you may have to use a thinner block for those heavy ones. Once you determine the right thickness for your needs , duplicate it and add to other mag. Installing the bushing on and off the prop before sliding on the shaft will keep you from bending the shaft.
  I had an oppurtunity to take one of the 1/2A props to a facility and set it up on their hy-tech balancer to see how well the mod worked. It was .0002 oz. inches out of balance, for us simple people, that's pretty darn good.  Other data was collected and as soon as I get a chance, I'll lay it out here.