OS .29 Twinstack question - Currell?

Does anyone know the size of the propnut for this guy. Seems that an american nut is close but strips out when you try to tighten it. Finally mounted this on an old Skyray and now can't fly it today. Nuts!

Cary,
Can you get a metric nut off of another O S engine?? It could be a ten milimeter nut. Try this and see if it works.. If not take the engine to a parts store that carries metric bolts and nuts...
Good luck,

Can you measure the diameter of the thread? It would help a lot. Probably 6mm.

>Does anyone know the size of the propnut for this guy. Seems
>that an american nut is close but strips out when you try to
>tighten it. Finally mounted this on an old Skyray and now
>can't fly it today. Nuts!

Gary,
Your OS29 Twinstack has an M7x1 propnut. Blind Freddie could have worked that out!
It is not a common metric size and you are unlikely to buy one at your local hardware store.
However..........older #6001 Enya 35s and 45s use the same nut.
Contact me offline if you can't locate one.
regards
Dave

And make sure you get the correct thread pitch. Currell

>>Does anyone know the size of the propnut for this guy. Seems
>>that an american nut is close but strips out when you try to
>>tighten it. Finally mounted this on an old Skyray and now
>>can't fly it today. Nuts!
>
>Gary,
>Your OS29 Twinstack has an M7x1 propnut. Blind Freddie could
>have worked that out!
>It is not a common metric size and you are unlikely to buy
>one at your local hardware store.
>However..........older #6001 Enya 35s and 45s use the same
>nut.
>Contact me offline if you can't locate one.
>regards
>Dave

If unavailable anywhere,Altech does have them. Dennis

7mm x 1mm? This is one heck of a thread. Am I right in recalling that these engines were made for Bill Atwood for the American market? If so, seems they had to take what was offered? When we know for sure, can someone confirm lease?

>7mm x 1mm? This is one heck of a thread. Am I right in
>recalling that these engines were made for Bill Atwood for
>the American market? If so, seems they had to take what was
>offered? When we know for sure, can someone confirm lease?

Goddam, Ian. Just as well I checked.
Turns out OS used a rare thread first brought back from Outer Mongolia to the States by Yankee travellers in the late 1800s.
It is 11/40" x 25.4 tpi and was commonly used in Urdlu yak stirrups.
No doubt Bill Atwood was unaware of its humble origins and accepted it without question as a pukka American thread.
Only in later years was it recognised by the modern world as a useful size and renamed M7x1!
cheers
Dave

My handy & dandy Starrett chart shows 7m x 1 as a standard size, and only 1mm pitch in 7mm diameter. Your local hardware store may not have one, but a decent industrial fastener store should be able to supply them. Ask for Grade 8 or 10, while you're at it. Steve

I just recently bought some 7mm x 1mm metric nuts from my friendly Ace Hardware Store ..... it is a fairly common size actually. I bought these nuts for a few of my older Enya .45 engines, also I bought (from Ace Hardware) a few 6mm x 1mm metric nuts for some of my smaller size Enya engines.

Thanks everyone - Lovely SBC DSL has been down since I posted this so I was unable to reply. I give the local hardware a shot.

Thank you David and Injinnut. You now have me reaching for my Enya 45.

I have my Super Ringmaster drilled either for a Johnson or a Twinstack. I would put one of the Twinstacks (.29 or .36) on, but the Johnson S runs so well...