Propshafts

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28 May 2014 at 21:44 #49229
P. H. Stones
Participant
@p-h-stones25207
I'm having difficulty obtaining a replacement propshaft i.e. without a tube.

This should be of stainless steel – 370mm long – 4.8mm dia – 5m thread at one end only.

Having tried several dealers without success I approached a local metal firm who can make one for me but the cost would be exorbitant, some £40 – £50.

Any suggestions for a supplier will be gratefully acted upon.

Thanks
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28 May 2014 at 21:44 #5306
P. H. Stones
Participant
@p-h-stones25207
28 May 2014 at 22:05 #49230
Colin Bishop
Moderator
@colinbishop34627
Try Marks Model Bits **LINK** They are very helpful for bespoke items and charge fair prices.

Colin
29 May 2014 at 08:00 #49231
ashley needham
Participant
@ashleyneedham69188
PH. If your measurements are spot on this sounds like a 2BA shaft..is it an old boat?? may have an issue if it is a BA size.

5mm thread will screw in to BA props if memory serves.

Ashley
29 May 2014 at 08:59 #49233
lnvisibleman
Participant
@lnvisibleman
You can get the shaft from here. They will be happy to make a 2ba shaft the size you require at a sensible price.

http://www.mobilemarinemodels.com/acatalog/Sterntubes_Propshafts.html

Mike
29 May 2014 at 17:40 #49248
P. H. Stones
Participant
@p-h-stones25207
Thanks for all suggestions which I will follow up. I did have some props made for this boat and they were M5. The gentleman at the metalwork firm told me that the shaft is 3/16ths dia (Imperial) so it appears one will be difficult to find 'off the shelf' but I'll try. I've owned the boat ( a 57" German S-Boat) for about five years, purchasing it unfinished from the constructor and I have wondered what brushed motors (3) to install. There is not a great deal of space so something powerful enough for scale speed but not too large would be preferable.

Paddy
29 May 2014 at 19:09 #49252
ashley needham
Participant
@ashleyneedham69188
Mike. Hmm interesting. I could do with two 2Ba shafts for my Manchester destroyer..but the question is…are the actual shafts 2Ba or 5mm threaded for 2Ba at the ends?? I would want actual 2Ba shafts as the tubes bare 2ba sized bearings.. Will have to e-mail the firm to find out.

Ashley
5 June 2014 at 23:59 #49461
Len Morris 2
Participant
@lenmorris2
Dear PH,

I just wonder what question you asked you local engineering firm when your quote was £40-£50. Imperial 3/16 converts to 4,7625mm which is one and a half thou down on your 4.8mm size. This might not sound a lot but it is a big number to an engineering firm and the only way to get to a none standard size of 4.8mm would be to centerless grind a piece of 5mm bar which is not a cheap process. At 3/16 your material cost should be about £1.50 or £9.00 for a 2 metre length. Try West Yorkshire Steel for a supply **LINK**.

Len
6 June 2014 at 09:29 #49464
Malcolm Frary
Participant
@malcolmfrary95515
A new metric shaft and a pair of bearings to match might be the simplest and cheapest option.
6 June 2014 at 21:02 #49492
P. H. Stones
Participant
@p-h-stones25207
Marks Model Bits couldn't help but it seems that Mobile Marine Models probably can and I have sent them a damaged original to copy. I am optimistic that the required shaft will shortly be forthcoming. Meanwhile my thanks to all those offering advice.
6 June 2014 at 21:18 #49493
lnvisibleman
Participant
@lnvisibleman
Posted by P. H. Stones on 06/06/2014 21:02:56:

Marks Model Bits couldn't help but it seems that Mobile Marine Models probably can and I have sent them a damaged original to copy. I am optimistic that the required shaft will shortly be forthcoming. Meanwhile my thanks to all those offering advice.

Just make sure they don't copy the damage too !
12 June 2014 at 22:02 #49624
P. H. Stones
Participant
@p-h-stones25207
Latest information is that MMM cannot help after all. The size 3/16 is not stocked and to buy it in would cost the firm £48 for a 5' length in addition to which would be their time! MMM is returning the sample I sent them together with a carbon reinforced steel rod (free of charge) as a short term stopgap should it be required. Removal of the propshaft tube for complete replacement is not an option so the search goes on.
12 June 2014 at 22:31 #49625
Keith Long
Participant
@keithlong89920
3/16in. dia 316 grade stainless stell rod is available through E-Bay for about £11 for a 500mm length delivery foc. if the propshaft really is 3/16 in. then the thread should be 2BA rather than 5mm – a 5mm thread should be 5mm od not 4.7. The pitch of the 2 threads is very nearly the same – but there is a difference, and the angle of the threads is different. 5mm stainless steel rod (303, 304 etc) is also available via EBay – and cheaper than 3/16 – will 5mm fit the propshaft tube? Threading the end is simple with the correct die – you just need to know which die you really need. I suggest you put a posting on the Model Engineering website forum – a sister to this one – asking if someone can help you out. It's literally a 10 minute job to make the sahft if you've got the rod and the correct die. If you do seekhelp via Model Engineer please include your location in the request as it's much easier if somewone lives around the corner rather than the opther end of the UK or t'other side of the Atlantic or World.

Edited By Keith Long on 12/06/2014 22:32:15 – the keybord can't spell!!!!

Edited By Keith Long on 12/06/2014 22:33:04
13 June 2014 at 11:24 #49633
Malcolm Frary
Participant
@malcolmfrary95515
Like I said earlier, the simplest method is almost certainly to pop the original bearings out and fit a present day shaft. Fitting new bearings into the existing prop tube should not be rocket science. You then have a shaft that will take easily available present day standard fittings.
13 June 2014 at 11:47 #49634
Trevor Holloway
Participant
@trevorholloway99134
I had a similar problem in that I fitted a cheap propshaft assembly into a boat and the shaft rusted (hence why it was cheap).

I managed to get a replacement tube assembly inside the old outer – a bit of epoxy resin sorted out the sealing .

Maybe going down to 4mm thread would mean the new tube will fit within the old tube.
16 June 2014 at 20:40 #49737
P. H. Stones
Participant
@p-h-stones25207
After much thought and considering all the options offered by contributors, I finally decided that e-bay was the best choice for me and have purchased a 1000mm length of 3/16 stainless steel rod costing £13+ (only slightly more expensive than 500mm at £10+). This will make two propshafts which can then have threads cut as per the original. The spare can always be used on another boat. My grateful thanks for the many helpful suggestions.
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