Strong casting alloy? And machining something else

[stuvy]

OK thanks. I get the message. I did say I was investigating the possibility.... Getting one made from stainless is one of the options, although having no lathe I can't just knock one up :-(
Incidentally, I have bronze in the form of my old propeller (in VGC, no dezincification, changed due to engine swap).
For my enlightenment, just looking up propeller bronze & Propellerpages.com mentions Nickel Aluminium Bronze. which has a pretty similar composition to AB2 - why the "no way cast it in ally"? Looks like an ideal candidate, but it seems not - why's that? Thanks.

Ask on here, more than a few members that will be able to do it for a couple quid

 

[Jonathan Webb]

It’s highly likely that your prop is actually brass rather than bronze, unless it’s really old. Although brass is pretty useless in salt water, they get away with it for a prop because it’s pretty chunky, and if it fails it does so slowly and visibly, rather than catastrophically like, say, a keel bolt.

Not sure about that assertion although I'm only a layman. T Norris, one of the major prop suppliers: https://shop.tnorrismarine.co.uk/collections/standard-manganese-bronze-propellers-propeller-prop Eliche Radice https://www.elicheradice.com/product-line/bronze-propellers/ ( Otman & Mibral alloys) & Michigan wheel "We build our Standard series propellers in Manganese Bronze (CU1) or in Nickel Aluminium Bronze - NiBrAl (CU3" https://www.mmp-i.com/images/downloads/Standard Series Propellers (2).pdf

 

[Brad93]

I'd be half tempted to get one cut out of some 15-20mm stainless, then grind and file to shape.

 

[Newlands]

Not sure about that assertion although I'm only a layman. T Norris, one of the major prop suppliers: https://shop.tnorrismarine.co.uk/collections/standard-manganese-bronze-propellers-propeller-prop Eliche Radice https://www.elicheradice.com/product-line/bronze-propellers/ ( Otman & Mibral alloys) & Michigan wheel "We build our Standard series propellers in Manganese Bronze (CU1) or in Nickel Aluminium Bronze - NiBrAl (CU3" https://www.mmp-i.com/images/downloads/Standard Series Propellers (2).pdf

Yes, some of the more expensive ones are bronze (although the term ‘bronze’ is pretty loosely applied in some cases, as they actually include zinc in the mix). If you clean up a few old props you can easily spot patches of de-zincification on many of them, which tells you straight away that they are a brass alloy rather than a true copper-tin alloy.

 

[Jonathan Webb]

I'd be half tempted to get one cut out of some 15-20mm stainless, then grind and file to shape.

Someone else is getting quotes for that . Ive emailed Abbey Spuncast for a quote. We're seeing if a group buy is viable.

 

[Jonathan Webb]

There is a foundry in Hurstpierpoint that cast bronze and aluminium.

White Eagle Foundry Ltd - Non Ferrous Sandcasters

UK based precision sandcasting foundry, pouring in aluminium and copper-based alloys.

www.wef.co.uk

 

[Keith 66]

Boom end swivel fitting, The similarly shaped one on my same sized boat has the outer part welded from 316 stainless rod, the centre boss is just a piece of 8mm flat bar with a hole in it for the swivel bolt.

 

[Jonathan Webb]

Boom end swivel fitting, The similarly shaped one on my same sized boat has the outer part welded from 316 stainless rod, the centre boss is just a piece of 8mm flat bar with a hole in it for the swivel bolt.

Interesting design - better than machining it out of big lump. The original one is pretty light & it's a place where you don't want more mass than you have to ahave, which is one of the reasons I was pursuing this route over getting one fabbed.

 

[500e]

So basically an oval ring with a bush welded in.
Simple and cheap like it @Keith 66

 

[Jonathan Webb]

So basically an oval ring with a bush welded in.
Simple and cheap like it @Keith 66

It needs a bush, especially if the thing was made of stainless - the boom pin is presumably the same aluminium alloy as the swivel - quite soft. Can't make out the plastic (not Tufnol), but Acetal/Delrin/Pom would be good. The main hole is 13mm deep plus bush flange - the thinner the piece is, the greater the force exerted rotationally along the shaft axis, causing the leading edge to dig in (as if it was trying to snap off the shaft)