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Lynn,
Thanks, I have spun up the rotor in a lathe and
filled the rotor with coolant from a spray bottle, being careful not to spill
any and then weighing the remainder and comparing it to the original weight
(similar system to what you suggest). I went the extra mile and then adjusted
the weight by comparing it to oil weight of the same volume.
I did speak to Richard Sohn at the time but at that
stage he wasn't to concerned with balancing to that extent with his
demonstrator.
It has also been suggested that the apex seal and
springs be excluded as their weight is borne by the rotor
housing.
Then again I've had people argue against those
suggestions.
I thought any out of balance might exacerbate the
negative torque pulses, but your saying because their so large it's not
such a concern - which puts my mind to rest.
I do like your suggestion of 'reverse
engineering' the balancing process, I think I will discuss that with a
professional balancer.
George (down
under)
Lynn,
With balancing my single rotor, what would you
suggest that I allow ( percentage wise) for oil weight in the rotor - it was
suggested to me that I should allow full rotor oil weight.
This discussion suggests otherwise.
George ( down under)
George,
The process I saw on
the internet came from Down there. A rotor is spun up in the lathe with a
plastic shield around the outside. Oil is squirted in until it starts spilling
out. A pan is slipped under the rotor and the lathe stopped. (if your lathe
has a coolant system that would work as well with less mess) The weights are
close enough. Then the rotor is laid on a grill on the pan and allowed to
drain. Then weigh the liquid in the pan. I bet the balancing people just have
a number on the wall for rotaries that is close to that weight. A balancer
could do it backwards by spinning the shaft from a factory built engine, with
the counterweights mounted, and then add bobweight until he gets a balance.
Then subtract the rotor weight from the bobweight and that difference would be
the oil allowance.
The big name builders
all balance to a gnats butt weight, but I just get the rotor weights the same.
Never a problem. The single pulse per revolution will be so big that a small
balance error will go unoticed. But, its no sin to start out with the balance
correct. I have thought about singles and decided that as big a diameter
flywheel that you can fit but weighted only at the outer edge. Like 4 sets of
starter rings tiged to a flex plate. Even Mazda builds with pieces two weight
ranges apart. They have stamped the weights on rotors, and have used colored
paint dots. Of course the paint dots are gone when we see a used rotor.
Richard Sohn can tell
you. He seems to be doing well with his.
Lynn E.
Hanover
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