----- Original Message -----
Sent: Wednesday, October 07, 2009 4:04
PM
Subject: [FlyRotary] Re: Balls and
Springs
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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Date: 10/07/09 05:18:00