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Old Mar 08, 2013, 04:42 AM
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Crank too long?

This might sound like a stupid question, but here goes!

I've got an OS91 and the threaded end of the crank shaft is too long to fit the spinner combination I want to use. Has anyone trimmed/shortened their crank shaft?

I can see a dremel with cutting disc would provide a neat cut.

Am I being stupid???

Cheers
Hack
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Old Mar 08, 2013, 05:01 AM
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Afraid to Hack?
Modify the spinner in the first place!
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Old Mar 08, 2013, 05:09 AM
Complete RC Idiot Savant
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Quote:
Originally Posted by hack_1979 View Post
This might sound like a stupid question, but here goes!

I've got an OS91 and the threaded end of the crank shaft is too long to fit the spinner combination I want to use. Has anyone trimmed/shortened their crank shaft?

I can see a dremel with cutting disc would provide a neat cut.

Am I being stupid???

Cheers
Hack
With that engine and a normal prop, usually the threaded end of the crank is protruding less than 5 mm from the nut...

So I have the feeling, your spinnercombination is not suitable for this engine.
I think it is wiser to find a different spinner, in stead of cutting the shaft..

Having said that,, provided you go about it carefully, protect the engine from ingestion of grinding dust, I think it does not really harm the engine if you would shorten the shaft with a Dremel cutting disk. I have done similar jobs without any negative results.

Brgds, Bert
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Old Mar 08, 2013, 05:56 AM
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That is odd. I would agree with Brutus1967 in that it sounds like the propeller may be too small in pitch or you have too thin of a prop washer or something. Maybe a more thick prop washer or more than one prop washer. Use a prop nut and then use the spinner nut for the spinner.

But people have shortened the crankshaft tip by cutting it off with a dremel cutoff tool before. Do protect the engine from the metal and dust from the cutoff wheel.
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Old Mar 08, 2013, 05:58 AM
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Hack,

I don't know your spinner in detail so in general I see this!
Sometimes drilling a hole can solve the problem.
So show more details please!

Taurus Flyer
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Old Mar 08, 2013, 05:59 AM
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I would modify the spinner before cutting off the crank.
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Old Mar 08, 2013, 06:32 AM
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To modify a Super Tiger (like) spinner you can extend the threaded hole, if it is a blind nut for example. For this modification the best way to do is using a lathe.

Hack , hack the shaft will reduce the value of the engine!!!

Taurus Flyer
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Last edited by Taurus Flyer; Mar 08, 2013 at 06:59 AM. Reason: edit picture
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Old Mar 08, 2013, 06:35 AM
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I wouldn't touch the crank...
Just put a piece of plywood between the spinner and propdriver.
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Old Mar 08, 2013, 08:54 AM
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I suspect what his problem is that the special spinner prop nut bottoms out on the crankshaft tip with the spinner, propeller and prop washer he has. What I do is use the engine's prop nut and tighten it all up with it, and then screw on the spinner prop nut and tighten it down. So you have sort of double nutted it then. Usually you wind up having to shorten the screw used to hold the front spinner part on anyway. No big deal cutting a little off with a dremel cut off tool.
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Old Mar 08, 2013, 12:05 PM
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That's what I thought but didn't want to type that much last night
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Old Mar 08, 2013, 09:04 PM
TigreJohn
United States, CA, Corona
Joined Aug 2008
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Another possibility is he is using both crankshaft nut and the adapter nut. And with that added length, the spinner could be hitting the adapter nut, not the crankshaft. If thats the situation, I would shorten the adapter nut if his engine is a four stroke. And keep using the two piece crankshaft nut. If his OS is a two stroke and the adapter nut is steel, leave off the crankshaft nut and use the adapter nut to tighten the prop.
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Old Mar 08, 2013, 09:21 PM
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I have gotten creative with using different spinner nuts before. The old classic CB Associates spinner nuts were great for many purposes like this when the regular Tru-Turn or some other spinner nut wasn't quite right. I have had to make them before too, using brass hex rod and drilling and tapping as needed. Where I tapped one end for the crankshaft and the other for the spinner screw.
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Old Mar 08, 2013, 09:48 PM
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"Crank too long?"

(Laughing like Beavis and Butthead) Huh-huh-huh, heh-heh, huh-huh, heh-heh.
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Old Mar 09, 2013, 01:19 AM
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I could use a longer crank, myself.
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Old Mar 09, 2013, 02:56 AM
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Quote:
Originally Posted by Gooroo View Post
"Crank too long?"

(Laughing like Beavis and Butthead) Huh-huh-huh, heh-heh, huh-huh, heh-heh.
Hey Butthead.... huh-huh.... he said "crank".....

Yeh, Hm, heh heh, he said crank, hehe....

Love that show!

Brgds, Bert
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