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 Prop shaft and tube

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Akamini
Deck Hand
Deck Hand


Posts : 13
Join date : 2020-01-05

Prop shaft and tube Empty
PostSubject: Prop shaft and tube   Prop shaft and tube EmptyTue Jul 07, 2020 8:42 pm

Building an MFA spearfish MK2 I acquired and going to run a fast brushless setup which could hit 24000rpm. Any advice on an appropriate prop tube/shaft to use? I'm thinking a normal brass tube with bushings isn't going to like those speeds, so what sort of thing can you use for this type of application?
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Roadrunner
Forum Overlord
Forum Overlord
Roadrunner

Posts : 1673
Join date : 2011-06-10
Location : Aberdare South Wales

Prop shaft and tube Empty
PostSubject: Re: Prop shaft and tube   Prop shaft and tube EmptyWed Jul 08, 2020 12:34 am

Surprisingly a m5 size stainless steel prop shaft and tube wth brass bushings will hold up for a long long time with beast size brushless motors providing you grease them up and keep on top of it.

You could also fit an oiler to the shaft and top the oil up after every run if your not a greaser... 


Usualy the only things to wear on a standard shaft would be the thrust washers but you can swap those out to Teflon like I do and run for years without issue.

There are other option in the forum of flexi shafts however they will rust ( used mostly in the ic power boats) those required full strip downs & cleaning After every run to keep them in top condition.

I’m confidant to say that for The spearfish that a m5 shaft will do the job and give you many years of trouble free use regadlrsss of the brushless motor providing you get the alignment right. A brushless motor will always put out less stress on a shaft than an ic engine will ( basically no vibration) and is the go to shaft for 99% of model boats excluding the fast electrics with outrigger setups and ic boats where the shaft is required to be bent to fit the running gear. Something the spearfish dose not need.

Roadrunner

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Akamini
Deck Hand
Deck Hand


Posts : 13
Join date : 2020-01-05

Prop shaft and tube Empty
PostSubject: Re: Prop shaft and tube   Prop shaft and tube EmptyWed Jul 08, 2020 8:13 am

Thanks! Guess I'll stick with brass and steel and plenty of grease, makes life a bit easier. Cheers
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Akamini
Deck Hand
Deck Hand


Posts : 13
Join date : 2020-01-05

Prop shaft and tube Empty
PostSubject: Re: Prop shaft and tube   Prop shaft and tube EmptyWed Jul 08, 2020 2:20 pm

Follow up question - should I stick with a threaded prop, or look to use a drive dog? Again, at those rpm I wondered if drive dogs were a more secure option than a threaded prop and locknut. If a drive dog is a better option, is there a specific type of shaft to use - they seem to clamp onto an unthreaded shaft with a grub screw? Thanks
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Roadrunner
Forum Overlord
Forum Overlord
Roadrunner

Posts : 1673
Join date : 2011-06-10
Location : Aberdare South Wales

Prop shaft and tube Empty
PostSubject: Re: Prop shaft and tube   Prop shaft and tube EmptyThu Jul 09, 2020 3:32 am

Either is fine both have pros and cons, personally i just use threads props for the most part and make sure the nut on the back is jam tight to the prop itself and a little bit of lock tight so it reduces risk of throwing it, nothing worse than throwing a £25 brass prop I tell ya, but you’ll probably use a plastic/grp based prop so a threaded will be good enough.  Dog drive props tend to be for the more exotic pitches in the racing areas, nothing stopping you using them tho, but the sword fish dose very well on a x40/45 size prop at decent rpm (16-22,000)

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