Do I replace a old propshaft

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Do I replace a old propshaft

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6 January 2012 at 21:45 #32886
Peter Herwin
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@peterherwin40859
I am back into modeling after 30 odd years and would like your advice I started on a 46inch fibreglass hull designed on the lines of the Moonraker made by staff at Lotus Cars 30 plus years ago, I fitted the propshaft but think it has a 4ba tread instead of the 4mm tread on todays shafts so propellers will be a problem, can I change the rod and leave the brass tube are they the same outside size or would I be better to change the complete shaft to a better quality as I am fitting a brushless 1000kv motor with 60 amp speed controller and 3s battery so revs will be high. Any advice appreciated.

Regards Peter.
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6 January 2012 at 21:45 #2092
Peter Herwin
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@peterherwin40859
6 January 2012 at 21:55 #32887
Tony Burton
Participant
@tonyburton83970
Hi peter’

I have a twenty two years old Pilot ship which has laid in my shed and just refitted last year. The prop shafts were badly pitted and I tried to get new shafts, but they are a bigger diameter.

With it only a steady ship i decided to pack them with grease and they don`t leak.

With yours being a fast boat i would be inclined to change to modern shafts if its not too difficult to get the old ones out.

Tony
6 January 2012 at 22:09 #32888
Peter Herwin
Participant
@peterherwin40859
Thanks Tony,

I did`nt think it would be that simple, is there a shaft that would be better than the standard brass type or will they cope ok if lined up with double coupling ?

Thanks Peter.
6 January 2012 at 22:40 #32890
Colin Bishop
Moderator
@colinbishop34627
If your present shaft is OK then you should be able to get props threaded to 4BA to special order from the Prop Shop: http://www.prop-shop.co.uk/ An original 4BA shaft in a brass tube is pretty substantial and should cope with most demands you are likely to place upon it.

Otherwise, as Tony says, it’s probably best to replace the complete driveline. Application of heat (with a soldering iron or similar) to the tube should break the old glue bond and allow the old tube to be extracted (possibly with some light application with a hammer!)

Colin
7 January 2012 at 09:07 #32891
ashley needham
Participant
@ashleyneedham69188
I have replaced several propshafts for one reason or another. I use the jolly old dremmel to cut as much as poss around the shaft inside and out, then heat and hammer. One has to take solace in that the shaft bis normally not on view so a bit of making good will largely be unnoticed (hopefully!)

Its a shame that you cant seem to find 4ba shafts in stainless,as I could do with a longish pair to replace those in my HMS Manchester, and a couple of other older boats which have pitted badly. They still work ok, but need constant cleaning and regreasing.

I had a scout round some while ago and couldnt even find stailnless rod to the right diameter to buy and have a go at threading myself.. must be a modest demand for 4ba stainless..all those poeple with old boats??

Ashley
7 January 2012 at 15:27 #32893
Peter Herwin
Participant
@peterherwin40859
Thanks Ashley, I will pick up a new shaft next weekend I am in Yarmouth and need a few odds and ends and with 4mm have a choice of props to use as I only have a 30 and a 40 in ba I think so no good getting boat finished and no propellers to use

Regards Peter.
7 January 2012 at 17:35 #32894
Len Ochiltree
Participant
@lenochiltree67043
Try this chap, Folkestone Engineering Supplies

WEB SITE http://www.metal2models.btinternet.co.uk

Len.
8 January 2012 at 19:32 #32907
Peter Herwin
Participant
@peterherwin40859
Thanks Len,

Looks a good site to keep on list very useful.

Peter.
17 February 2012 at 22:52 #33425
Peter Herwin
Participant
@peterherwin40859
Along gap from last post but been busy away on holiday spraying boat coming on slowly, I took the shaft with me and it turned out it is a 5mm so no need to change as 5mm props are avalable can not beleave I bought it 30 plus years ago and it was in mm back then but good can leave shaft intact
18 February 2012 at 09:21 #33434
ashley needham
Participant
@ashleyneedham69188
That handy, eh !! but, purchase a stainless propshaft for the tube though, fit and forget.

Ashley
18 February 2012 at 09:40 #33435
Bob Abell 2
Participant
@bobabell2
Hi Peter!

Don`t be surprised if your old 5mm shaft….Turns out to be 2BA!

Bob
18 February 2012 at 20:33 #33445
Peter Herwin
Participant
@peterherwin40859
Hi Bob,

I took the inner shaft to model shop and was told it was 5mm so bought two propelors so asume it is 5mm the shop owner spun them on so they fit

Regards Peter.
18 February 2012 at 21:28 #33447
Keith Long
Participant
@keithlong89920
Hi Peter

5mm and 2BA are very close to each other in size, but the 5mm is very slightly larger diameter than 2BA so would be a sloppy enough fit to go on. The pitch of 2BA is 0.81mm while 5mm pitch is 0.8mm. Also the angles on the thread flanks are different BA is 47.5 deg, 5mm is 60 deg. At the very least I'd check the shafts thoroughly to make sure what the thread is and if you're going to be putting any sort of power or speed through it I'd suggest using one of the Loctite type thread locking compounds as an additional safeguard. Could be embarassing if you loose the prop in the middle of the lake.

Keith
18 February 2012 at 22:16 #33449
Dave_P
Participant
@dave_p
And that is embarrassing believe me!

Seriously Keith's advise is spot on.
18 February 2012 at 22:47 #33452
Peter Herwin
Participant
@peterherwin40859
Hi all

Thanks for the advice I will check it out and make sure as it will have high revs as I am using brushless 1100kv and 3s lipo, I will need advice on them when I start to fit as I feel I may regret taking that root after reading some posts on lipos, oh well time will tell

Regards peter.
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