His opinion is that a one-inch crank throw is about  maximum for a
manual
lathe  which is far less than an e shaft would require.

Hi Y'all,
the "throw" ie, the eccentric on the eshaft, is 15mm, a little less
than 5/8 inch. But I think you mean throw in the lathe sense; but still
only about 3 inches; many home lathes are up to this task since you
will be sending it out for finish grinding.
 And, a single shaft can be turned out of a twin shaft, the only
singles I know of, (3), have e shafts turned from twin shafts. And
despite what has been said on this newsletter over the past 2-3 years,
the Mazda twin rotor product is more than strong enough to withstand
10,000rpm in racing. What is all this talk of porosity, casting
densitiy etc Ask Abel Abarra, or Guru. They actually do it, not talk
about it. The single shaft has a main bearing on each side of the
rotor, ie in each side housing, so it has a much smaller bending moment
and so less prone to failure.
So what is the source that states a Mazda single shaft will not be up
to the task? Any single that has seen the light of day has not failed
because of eshaft problems; as a matter of fact I have not heard of any
single rotor engines failing. I have discussed many balance problems,
torque pulse problems and vibration issues, but to date not one eshaft
failure. So, to para-phrase Tracy some months back, "where do you get
this stuff"
BR, Dave McC

David,
Speaking of the single e-shaft - this information comes from ME and MY
research of having the Mazda e-shaft extensively ( read expensively) tested
and also having a number of  EXPERTS in the field of metallurgy provide
their opinion.
Now when you feel you have the expertise and have spent the money on testing
please feel free to provide the outcomes of your testing.

BTW X-treme has followed the same path as myself in this regard and has come
to a similar conclusion. Casting is by far the cheapest way to go with crank
shaft - do X-Treme go that way, the answer is a definitely NO!!!

The Premo way of producing cranks is as Paul suggested and that is Forging.
I could go on about this but it would be lengthy - suffice to say that not
all metals are what they used to be.
George (down under)


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