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Author Topic: 2BA Props  (Read 819 times)

mudway

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2BA Props
« on: May 18, 2018, 08:59:01 AM »

Just acquired an old model needing some TLC which has a 2BA shaft in it and too large a prop on it.


Does anyone make a 2BA prop these days?
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chas

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Re: 2BA Props
« Reply #1 on: May 18, 2018, 12:52:56 PM »

If my old memory serves me correctly, 2 ba is slightly under 5 mm. It might be worth trying a 5 mm prop on it if you have one and seeing if is secure. I'm not sure you could re thread it, there is probably not enough metal to do it properly.
Chas

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mudway

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Re: 2BA Props
« Reply #2 on: May 18, 2018, 02:00:05 PM »

Thanks, I've tried a few M5 props but the thread is different. You can screw them on but only for a short distance. Not enough to secure them om the shaft.
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steamboat66

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Re: 2BA Props
« Reply #3 on: May 18, 2018, 03:58:52 PM »

protean design, he does odd stuff to order.
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chas

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Re: 2BA Props
« Reply #4 on: May 18, 2018, 04:05:15 PM »

I was afraid that might be the case. Is their any chance you can re bush the existing tube to take a 5 mm shaft? Otherwise you can investigate the removal of the whole tube and shaft. Heat applied to the tube with a mini blowtorch or soldering iron and giving it a twist with pliers or grips usually does it. Assuming you can get at it.
Or, maybe some older modeller will have a stash of old props. The cost of having props specially made is high and you have to consider buying couplings, so I doubt that is a practical solution. What type of model is it? we're mostly a nosy lot on here
Chas
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Fred Ellis

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Re: 2BA Props
« Reply #5 on: May 18, 2018, 06:22:04 PM »

Hi


Have a word with Deans Marine, I think that the props on my Dean's HMS Bulldog are 2ba, and he just my have some still in stock.


Fred
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mudway

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Re: 2BA Props
« Reply #6 on: May 19, 2018, 09:10:45 AM »

I was afraid that might be the case. Is their any chance you can re bush the existing tube to take a 5 mm shaft? Otherwise you can investigate the removal of the whole tube and shaft. Heat applied to the tube with a mini blowtorch or soldering iron and giving it a twist with pliers or grips usually does it. Assuming you can get at it.
Or, maybe some older modeller will have a stash of old props. The cost of having props specially made is high and you have to consider buying couplings, so I doubt that is a practical solution. What type of model is it? we're mostly a nosy lot on here
Chas


Thanks Chas but that won’t work for this beast. It is an old Precedent f/glass 34” Huntsman which used to be petrol powered. The guy who built it knew what he was doing. The hull inside has been beefed up by laying down more glass and also adding core matt to reinforce various areas and then flow coated it. The prop shaft is fibre glassed into the hull. The result is a hull that weighs a tad under 2kgs.
He did a nice job, the only paint on the hull is a strip of blue where the deck joins. Otherwise it is a well preserved and polished gel coat hull. I don’t want to damage it if I can help it.
The problem is that it came with the remnants of a metal 52mm (!) prop and a spare 55mm plastic prop. I want to go electric with either a John Darke 780 series motor or brushless. For that I figure I need to reduce the prop to a 35 or 40mm one.
The hull might be in good nick but the superstructure is distinctly “sad and tired”.
What I might try is to regrease the tube and then fit a 5mm shaft in, leave it well ballasted, put it in the test tank and see how much water comes up the tube.
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Shipmate60

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Re: 2BA Props
« Reply #7 on: May 19, 2018, 09:34:06 AM »

SHG do supply bearing ends in a nylon like material.
You could fit these at each end and fit a new 4 or 5mm inner propshaft.


Bob
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steamboat66

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Re: 2BA Props
« Reply #8 on: May 19, 2018, 01:20:53 PM »

the cost of a bespoke prop may me much less than is feared. the prop it's self needs only to be standard, the only difference is the thread.
 
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malcolmfrary

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Re: 2BA Props
« Reply #9 on: May 20, 2018, 08:46:19 AM »

What is the inside diameter of the existing tube?  It might be possible to remove the bushes and slide a complete M4 assembly into the tube.  The world is then your lobster as regards choice of props, and M4 should be plenty for a 34" Huntsman.
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canabus

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Re: 2BA Props
« Reply #10 on: May 20, 2018, 09:07:54 AM »

My Precedent Huntsman 34", I removed the old bushes and Install a Teflon 4mm bottom bush and a brass top bush.
I am run a 35mm brushless Hobbyking 3648-1450kv on 3S Lipo battery with a 2 blade 40mm CNC prop.
Stacks of power good run time and nice and quick.

Canabus
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mudway

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Re: 2BA Props
« Reply #11 on: May 20, 2018, 10:44:40 AM »

What is the inside diameter of the existing tube?  It might be possible to remove the bushes and slide a complete M4 assembly into the tube.  The world is then your lobster as regards choice of props, and M4 should be plenty for a 34" Huntsman.
Malcolm, Great minds think alike. I remembered today that I'd had a similar problem with another boat which I'd built with a 3mm shaft and later on discovered that replacement M3 props were closely related to hens teeth. That time I managed to fit a slimline M2 tube straight into the M3 tube and just had to seal either end.


These would nearly fit after slightly drilling out the bushes to 6mm.    https://www.ebay.com.au/itm/8-FINELINE-MODEL-BOAT-PROP-SHAFT-M4-THREADED-BOTH-ENDS-6MM-O-D-TUBE/192536407029?hash=item2cd4106bf5:g:AccAAOSwLoxa9FHS
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SteamboatPhil

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Re: 2BA Props
« Reply #12 on: May 21, 2018, 06:54:39 PM »

Mudway
If you PM me your address I will send you a selection of 2BA props


Phil
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mudway

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Re: 2BA Props
« Reply #13 on: May 22, 2018, 03:44:09 AM »

My Precedent Huntsman 34", I removed the old bushes and Install a Teflon 4mm bottom bush and a brass top bush.
I am run a 35mm brushless Hobbyking 3648-1450kv on 3S Lipo battery with a 2 blade 40mm CNC prop.
Stacks of power good run time and nice and quick.

Canabus


Thanks, a friend down in Victoria also burst into life and recommended a Hobby King motor. His was a 3639 on a two blade 35mm. If possible, I'd like to stick to the John Darke motors as I have some in stock and I'm running a 36" MGB and 33" Brave both with his motors and a 35mm prop.   
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