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From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2912347@logan.com>
Subject: Re: [FlyRotary] Need ideas for bolts
Date: Thu, 8 May 2008 08:18:25 +1000
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Ernest,
Just as a comparison, I got a quote for high tensile, roll formed threads 
for the single rotor for $12 each, especially made up to length.
I think someone is having a lend of you.
Isn't that Tracy's rig, perhaps you can get bolts from him the right length.
George ( down under)

>I thought this would be easy.  It's not.  I'm trying to come up with a 
>better idea now.
>
> Problem:  The gearbox I have bolts up to a 1/2" plate.  There are 6" 
> standoffs between the plate and the rear face of the engine.  Two of the 
> standoffs are drilled to encompass a single bolt, and the other two are 
> wide enough to contain 2 bolts each.  We planned to use bolts through all 
> the pieces into the back of the engine.  The bolts would need to be 180mm 
> long M10 with a 1.00mm thread pitch.  Because it will be holding the prop, 
> I consider it prudent to specify 10.9 grade bolts (equivalent to Class8). 
> Wilders, the local bolt specialty shop, gives me a quote of $36 each.  I'd 
> need 6 of them.  I could get a box of 10 at $30.67 each.   Ouch!!
>
> I could do that, crying the whole time, and may possibly have to yet; 
> but, I think it might be smarter to explore other options first (and ask 
> people smarter than I).   I'm thinking the best way to go would be to find 
> a way to use standard length bolts.  For instance, for the two standoffs 
> that have two holes, we could cut a recess into each side to uncover the 
> drilled hole.  That would allow one bolt to attach the standoff to the 
> engine and another to attach the plate.  But that would severely 
> compromise the clamp-up forces that hold the whole thing together and 
> allow it to get "wobbly".  Threaded rod or studs are possibilities, but 
> I've not been able to find either.
>
> Where can I find extra long, high grade metric bolts that aren't specialty 
> order items?
> What other options do I have for securely bolting a plate to the back of 
> the engine with 6" spacer?
>
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