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General control line discussion => Open Forum => Topic started by: Andrew Tinsley on May 29, 2012, 06:28:10 AM

Title: crankshaft extension?
Post by: Andrew Tinsley on May 29, 2012, 06:28:10 AM
Hello all,
My command of the American language is letting me down badly! I am sure that Tower Hobbies sell what I would call a prop extension. Effectively I want to increasethe distance from the prop driver to the prop. So what is the US name for such a device? I have searched high and low in Towers and even the advanced search lets me down!
I know that Fox do or did such things, but I would want something for a TT GP42, so I suppose the thread on that would be metric. Can anyone help a poor limey who is separated from you by a common language!?
Title: Re: crankshaft extension?
Post by: Steve Thomas on May 29, 2012, 06:52:30 AM
Hi Andrew

How's this?  http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=shaft+extension&search=Go

(Searched 'shaft extension').

I think you'll find that the GP42 has a 1/4-28 thread, as do plenty of other Asian engines of similar size (eg OS and Enya). 

Cheers
Steve
Title: Re: crankshaft extension?
Post by: Dallas Hanna on May 29, 2012, 07:00:40 AM
'tis a shaft extension or prop shaft extension Andrew.   Veco had them wayyyyy back in 1/2" and 5/8" from memory.  They were all alloy, the nut having a 3/8" diameter section which extended through the prop into the cotton reel extension piece.  FOX also had a shaft extension similar in construction but the nut had a smaller section due to being manufactured from steel.   Maybe look on the Fox site.

OR

Send me the dimensions you need and I'll send one over to you!   I'm still on Skype so you can give me a call.  9 hours ahead of you at this time of year.

HH

Title: Re: crankshaft extension?
Post by: Andrew Tinsley on May 29, 2012, 09:13:13 AM
Hello Steve and Herb,
Looks as though the Fox one would work, I shall get back to the old guy who asked me! A gentleman by the name of Alf Howe, who is well into his eighties and has just returned to C/L after years on the dark side!
He joined Clapa, here in the UK, a few months ago and I was intrigued to see an ex Clapa member, rejoin after a 30 years gap! So I paid him a visit. I am the membership secretary of Clapa, hence my knowing this. He turns out to have been a flying buddy of Pete Tindal, (one of your mates Herb!) who is our current Chairman of Clapa.
To cut a long story short, he has built an own design, powered by a TT GP42 and it looks as though he may have a bit of trouble with the CG. He emailed me and asked who could make an extension for him, hence my search!
If the Fox extensions are OK, I will order one for him. If not, I will skype you Herb. Must help these new retreads!!! Not to mention that he is a great old boy!

Thanks both!

Andrew.
Title: Re: crankshaft extension?
Post by: Avaiojet on May 29, 2012, 09:46:10 AM
'tis a shaft extension or prop shaft extension Andrew.   Veco had them wayyyyy back in 1/2" and 5/8" from memory.  They were all alloy, the nut having a 3/8" diameter section which extended through the prop into the cotton reel extension piece.  FOX also had a shaft extension similar in construction but the nut had a smaller section due to being manufactured from steel.   Maybe look on the Fox site.
OR
Send me the dimensions you need and I'll send one over to you!   I'm still on Skype so you can give me a call.  9 hours ahead of you at this time of year.HH

Here's your Veco.

I probably purchased it new, wayyyyy back then.

I have a few of them. Since we moved to FL there's still boxes with model stuff I haven't unpacked.

I'll look, can say when?

Charles
Title: Re: crankshaft extension?
Post by: Dallas Hanna on May 29, 2012, 06:39:27 PM
Must add Andrew that when using a shaft extension they should be pinned to the drive washer on the engine with a short length of around 1/16" wire.  If you then use an alloy spinner the back plate should also be pinned to the shaft extension the same way.   This prevents the prop spinning the nut off.  Actually the best way is to have the extension made integral with the back plate of the spinner.  That way there is only one metal/metal joint.

Seeing Alf is a mate of Pete T, how about we make him a spinner as well!!   This is one with a 7/8" extension.  Makes a far better looking nose area and gets the main weight back quite a bit.

HH
Title: Re: crankshaft extension?
Post by: Brian Hampton on May 29, 2012, 08:33:46 PM
This is the shaft extension I made for my Stalker 61. The bobbin is threaded part way through so it screws onto the crankshaft (it only needs to be finger tight) with a lip at the front to take the bored out spinner backplate. The knurling extends out past the backplate to drive the prop.
Title: Re: crankshaft extension?
Post by: Dick Pacini on May 29, 2012, 08:40:51 PM
Here's your Veco.

I probably purchased it new, wayyyyy back then.

I have a few of them. Since we moved to FL there's still boxes with model stuff I haven't unpacked.

I'll look, can say when?

Charles

You're missing the aluminum stud.
Title: Re: crankshaft extension?
Post by: dankar on May 30, 2012, 08:40:30 AM
Hi Andrew

How's this?  http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=shaft+extension&search=Go

(Searched 'shaft extension').

I think you'll find that the GP42 has a 1/4-28 thread, as do plenty of other Asian engines of similar size (eg OS and Enya). 

Cheers
Steve            Enya has 7mm shaft and 1/4 28 will not work unless drilled to 7mm.  Fox has 1/2" extension, and 3/4" just like Veco. Andrew Fox still makes them and are more reasonable than Tower on shipping.
Title: Re: crankshaft extension?
Post by: Steve Thomas on May 30, 2012, 03:41:46 PM
Quote
Steve            Enya has 7mm shaft and 1/4 28 will not work unless drilled to 7mm.


Hi Dankar, that's no longer true for the most part. The old-style 45-II and 60-III still use 7mm, but pretty much everything else from the SS25 up to the 61CX now uses 1/4-28.

Cheers
Steve
Title: Re: crankshaft extension?
Post by: john e. holliday on May 31, 2012, 07:12:22 AM
The extension on my P-39 kept/stated coming loose on the LA.46.   Cured it using J-B Weld.   Extension glued to thrust washer.  I use the Fox Extensions available from Tower Hobbies. H^^