So your thinking that the centrifugal forces are what sheared the rivets?  It's pretty crazy how high the forces spikes could be from an unblanced fan. I've not see one yet that was just built and installed w/out being balanced and lived for any period of time. That kind of stuff fails spectacularly, once it starts to go you couldn't stop it fast enough to stop it from exploding.

As far as cnc'ing one, sure that can be arranged. Are we talking from billet or a casting or..?  Material?

Jarrett Johnson
www.innovention-tech.com

----- Original Message -----
From: Ernest Christley <echristley@nc.rr.com>
Date: Friday, May 20, 2011 3:24 pm
Subject: [FlyRotary] Re: Blower experiment:  FAIL

> I doubt any amount of balancing would have kept the blower
> together.  
> The highest RPM I hit was aroun 4000.  Most of the rivets were
> sheared
> cleanly.  My design was simply not anywhere close to robust enough.
>
> I've got a line on a company that will do one-off dynamic
> balancing in
> North Carolina.  Do you think I could convince you to mill me a
> rotor,
> and then I could get my whole assembly balanced?
>
>
>
>
> H & J Johnson wrote:
> > Ernest, did you get a high speed dynamic balance on your blower?
> I've
> > built blowers of a similar form and had good results, but only
> after
> > balancing to rated RPM.
> >
> > Jarrett Johnson
> > www.innovention-tech.com
> >
> >
> > -----------------------------------------------------------------
> -------
> >
> > Some of you may recall my blower experiment.  Using the shaft
> between
> > the flywheel and PSRU to drive a centrifugal fan to charge the
> intake.>
> > My implementation died in the crib.  before.jpg shows what it
> looked
> > like a week ago.  after.jpg is what was left of it after the few
> > minutes I was able to get the engine to run.  Well, that wasn't
> all
> > that was left over.  intake.jpg shows how the blades got thrown
> toward
> > the intake and smashed up against the air filter.
> >
> > Oh, well.  Until I can design and build or have built an
> impeller that
> > can handle 8000RPM, I'm going to table this experiment.  I still
> think
> > it is a good idea.  So did these guys:
> >
> > http://www.flightglobal.com/pdfarchive/view/1942/1942%20-
> %200142.html>
> > Furthermore, the calculator at
> > http://www.forestryforum.com/members/donp/Blowercalc.htm
> indicates
> > that with the 10.4" diameter, 3.35" deep area available for me
> to put
> > a blower, I should be able to generate 17" water column pressure.
> >
> > -----------------------------------------------------------------
> -------
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