making your own anodes...

stefan_r

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I want to make some anodes to fit my propellor locking nut as it is an odd shape and Duff etc don't make one to fit.

I assume this is a case of taking a plaster cast and melting zinc into it????

This seems all a bit too easy - what type of plaster can I use?? Where can I get 'anode quality' zinc from?? Has anyone tried this before??

Many thanks

Stefan

mailto: stefan@athito.com
 

AndrewB

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There was an article about this in PBO a few years ago, so it is certainly practicable. I remember the author used the zinc left on old anodes collected around the boatyard to make new ones, I think in a steel baking tin as a mould.

The melting point of zinc is something like 420C, rather hotter than lead, so you would need a decent mould material. For bronze casting, artists use a special ceramic that is oven baked before use. Maybe something similar? Zinc is soft and pretty easily worked though, specially if heated above 100C, so you might tackle shaping it it that way.
 
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Suggest you look at a helpful article in the june 2000 P.B.O.,page 139, entitled "Anodes - Reuse old ones",by Vic Crofts.This should give you answers to both questions - how to make a mould and a cheap supply of zinc.
 

oldharry

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You need to be certain you have pure zinc. Impurities (often found in industrial scrap zinc) can change the character of the metal and even only a few percent can make it useless for anodes. Collecting scrap anodes sounds to be the safest way of ensuring purity of the metal.
 

snowleopard

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nose to the ground...

i walked round my local boatyard and picked up a large number of scrap anodes which i melted in an old tin using a blowtorch. cost: nil, effort: lots!
 

Topcat47

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Re: nose to the ground...

This is the PBO reader website. Just because a post is old, doesn't mean it's irrelevant. For example, there may be people who might want to make their own anodes. It's not like a post reviving a queerie about sailing schools so old the main school recommended has closed.

I did my apprenticeship so long ago, we were taught how to whitemetal bearings. I tried making my own anodes about ten years ago, melting down my old stumps of anodes and sand-casting one in my back garden. It wasn't pretty, I ruined a pair of overalls, a good pair of 501's and a pair of shoes in the process, not to mention catching a nasty burn on my leg in the process. Although my apprenticeship was pre HSAW legislation, I had forgotten the heavy leather aprons and
solid "Tackety boots" that we wore when doing it, and the thick leather gauntlets. It's not a process I'd recommend, but it's something people might still be interested in.
 

superheat6k

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I have been making pencil anodes from old anodes for years. They dissolve at about the same rate as proprietary ones, so seem as effective. I am careful not to have any iron filings around when feeding the zinc because this can passivate the zinc.

I use 22mm copper pipe off cuts as a mould plugged by a 28mm stop end, from which I can cast 3 or 4 before the copper is knackered, with a crucible made from some 28mm elbows and a short length of 28mm pipe. I set this at about 30o in my vice then I feed the melting zinc in the top and the clean zinc runs to the bottom of the crucible, which I thoroughly heat also, I pre-heat the mould before pouring in the clean melted zinc, whist the crud and slag gathers further up the crucible and simply shakes out, ready for the next batch. when all the clean zinc is in the mould I give that a good blast to make sure it is all molten then leave it to cool. The cooled zinc slug simply taps out of the copper tube.

Finishing is in my lathe. I use a Turbo Torch with MAPP gas.

I would not try to make anything more complex or any larger.
 
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Re: nose to the ground...

This is the PBO reader website. Just because a post is old, doesn't mean it's irrelevant...

The statistics are a bit skewed at the moment as more people are aware of the problem. However ...

Do the majority of the replies address the question that necrobumped the thread? No.
Do the majority of the replies address the original post? Yes
Therefore this would be better as a new thread.
 
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