- Thread starter Leetig
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Tinbasherdan
Bodger in chief
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When you say repair what are we talking? A few chips out of the tip or a blade completely off, either way remember to get it balanced afterwards.and I doubt it will be straight bronze, tjo ive been wrong before. Props are usually phosphor bronze
Bronze (like brass) covers loads of different flavours of copper alloys. There are probably other members that know a chunk more about props than i do but off the top of my head aluminium bronze and nickel aluminium bronze are two of the 'top' flavours? Phosphor bronzes and manganese bronzes are cheaper(?), not as corrosion resistant (or strong) but that obviously depends on other stuff like fresh water vs brackish etc
Overview of welding copper alloys here http://www.twi-global.com/technical...ing-of-copper-alloys-brasses-and-bronzes-112/
Obviously knowing what alloy the prop is made out of is fairly high up on the list but none of the different filler wires are particularly cheap... expect to pay something like from £50ish upto £100/kg or over for Albronzes.
Overview of welding copper alloys here http://www.twi-global.com/technical...ing-of-copper-alloys-brasses-and-bronzes-112/
Obviously knowing what alloy the prop is made out of is fairly high up on the list but none of the different filler wires are particularly cheap... expect to pay something like from £50ish upto £100/kg or over for Albronzes.
Not too sure on exactly how bad it is. he is coming over tomorrow with it. I don't know what kind of alloy it is all he knows it's bronze! Don't mind about paying top dollar for rods as it's for a boat rental company so if all goes well should get return. What about brazing with silicon bronze?
Brazing with TIG or oxy fuel? The filler wires are very different but often called silicon bronze regardless, the TIG stuff (CuSi3, C9) is copper with a little silicon and has a melting temp ~ 900 - 1000°C (similar deal with CuSn7, C11 phosphor bronze wire) while C2 oxyfuel brazing rods are ~40% zinc and melt below 900°. Melting temp of the prop is gonna vary some depending what flavour bronze it is but with TIG you'll probably be welding whether you want to or not. The zinc in oxy fuel brazing wires might cause problems in the future, google propeller dezincification
I'm probably being paranoid but would've thought a boat rental company would be aware of various prop specialists... could be innocent reasons like lead times etc or could be they're trying to be cheap etc?
I'm probably being paranoid but would've thought a boat rental company would be aware of various prop specialists... could be innocent reasons like lead times etc or could be they're trying to be cheap etc?
Ha maybe they are trying to do it on the cheap but I can hardly blame them as they are endlessly replacing them! Doubt it would pay to have it repaired professionally as it wouldn't be in the water till it was bashed again!
chunkolini
celebrity artiste
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I have a heap of 'aluminium bronze welding rods, 3mm diameter.
If you want some drop me a line.
If you want some drop me a line.
Right so he dropped it up this morning it's not too bad a bit of build up mainly. I had a go puddling it and a def thing brazing is the way to go. As soon as I increased amps to puddle it it would start to spit back badly. However when I just heated to red it was fine. What is the big difference between aluminium v silicon bronze rod?
The spitting as it melted sounds like zinc volatisation (zinc boils at 907°C). If there was any white 'soot' that pretty much confirms it and the prop is probably manganese bronze which should really be called a brass due to it's zinc content?
Price, mechanical properties, ease of use, the TWI link covers the differences in the two alloys. Somewhere on the forum there's a few threads about using Al bronze and potential issues regarding arc stability/polarity due to the Al oxide. Drains is the member to cross reference searchs with, IIRC he was advised by the supplier to use a flux, i suggested AC and he ended up using the MACS setting on his Lorch which is a kinda mixed waveform, DCEN with some AC thrown in/overlayed
