06-06-03 09:50 PM - Post#20854 In response to Staff
I use the Koll Rotor Pro Balancer and a GOOD gram scale to balance ALL my blades. So far the claims of perfectly matched blades right out of the box has not been true for me! The weight may be the same but the CG is always WAY off!
The instructions are confusing at best and I don't do it their way.
If your blades came finished than the weights should already be installed and visible through the cover. IF they have weights! Some don't!
Check the weight of each blade. One may be heavier. If it is note the difference in the weights and mount it on the rotor pro. This will be your master blade. Balance it on the rotor pro. Mark the CG through the hole in the bottom of the rotor pro. Now remove the master and mount the slave blade on the rotor pro. You will now just place a piece of tape (equal to the difference in the blade weights) on the slave blade in a spot that centers the bubble level. At this time just set the tape temporarily on the blade.
Now both blades should be the same weight and balance span wise.
Mark a spot on the span wise CG on both blades. Now turn the rotor pro sideways and slide in the master blade centering it on the spot you just made. Level to get the chord wise CG. Mark the chord wise CG from below. Slide your span wise CG mark to match the chord wise position thereby combining the two marks into one. This will be your master blade CG point. Remove the master and check the slave. If you're lucky they will match. Most likely they wont! Try and position the your piece of tape toward the lite side of the blade to get the chord wise CG to match. If it does you're done. If it doesn't you will have to add more tape to the lite side until it does. Of coarse this extra piece of tape will make the slave blade heavier than the master and you will have to add a equal weight of tape to the CG of the master blade to get them back in balance. This is easy to do, just center it on your span wise/chord wise CG mark on the master blade. This will increase the weight but not change the CG so both blades should still match. Check one against the other to be sure.
Now although I told you the points are the blades CG the truth is there not. Why? Because the rotor pro is also being balanced with the blade. But it doesn't matter because what you're doing is getting the blades to match in weight/span wise CG/chord wise CG and they are. Its just that the actual CG although they are the same they will not be on your marks. Don't let this confuse you. Both blades are now exactly the same!
You can use any kind of tape. Tracking tape, clear tape just as long as it wont come off. Sometimes I just use Scotch Brand tape and so far its not come off.
If your blades are much different in weight you may not be able to do this with tape. That's when it gets tough! Drilling holes to glue in brass dust and all that! I don't mess with all that. I don't find the new built blades to be that out of balance as far as the weights are concernered. But if you build your own it can happen. And for that reason I don't bother building blades anymore. It doesn't hurt to take your rotor pro and gram scale to the hobby shop and check the blades before you buy if you can! You might get lucky and find that so called perfect set!
I think most people just check the weight difference, bolt them on and fly. But if you've already got the rotor pro you might as well do it right. At least you wont be wondering if that vibration is coming from your blades.