R_O_M
Guest
The rotor will have to be taken out of the machine to balance it. Our method, and there may be better ones around, is to first leave the left hand side, traffic sign end plate and bearing on. Check that this bearing is free spinning and replace if in any doubt while it is out. For the gearbox spline end, we were lucky as we picked up a broken gear box splined shaft [ how the hell anybody could manage to break this drive shaft right through is beyond me! ] An alternative is to get a short piece of shaft machined to a size to fit neatly without slop or play, inside of the splines in the rotor drive end. We then used a large bearing on the splined shaft or two small bearings in a mount so that the shaft sits in the V made by the bearings and rolls freely around. [ This V type, small bearing shaft support set up is a typical shaft and rotor_ fan _impeller type static balancing arrangement. ] Try and support the rotor as close to the end spider as possible as this reduces the effects of any play and sag of the shaft in the rotor drive end socket. The rotor should be fairly level end to end and very free to rotate. We then used heavy washers bolted to the spider plates and even extra nuts on some extra long bar retaining bolts when the rotor was a long way out of balance. Bolt the extra weight on in the lightest or top of the rotor position and give it a slow spin. It will stop and if the balance is close will oscillate back and forward a bit before settling down. When set up right and freely rotating even one extra washer can make the difference to the balance. Spread the balance weights in a couple of locations along the rotor as all the balance weights in one spot can cause dynamical balance problems. A dynamic balance is done as the rotor is run at speed and is by far the best but entails some decent equipment and generally taking the part to be balanced to a shop that specialises in balancing.