Aluminium cylinder, Viton rings

I've made my small engines with manly aluminium cylinders with viton o rings.

My next project I hope to run it on steam, so will also make a boiler for it so this will take me some time to do.

My question is, is aluminium a suitable material for steam.

Thanks Bob

Hi Bob what grade is the aluminium. it is possible to hard anodise and PTFE coat but you would have to know what grade as some grades don't work well.

David

Hi Bob. In a word, no. Definately not a good idea as it oxidises quickly when subject to steam. Your first run will probably be fine but after leaving it standing the bore will oxidise and make subsequent running worse and worse. Personally I would never use O rings as piston rings (I know some do with success) as they have no self lubricating properties, instead I would use graphite yarn for longevity.

I've seen several of Stew Hart's aluminium cylindered engines running on steam and they seem fine, just a good oil after use helps. I would not use it for a loco that is going to be doing a lot of work but should be OK on a small stationary engine run for display.

Rather than O rings, maybe try Teflon plumbers tape. I would use a harder grade of alloy for the cylinder.

Ian S C

Thanks for the replies,

I will try the graphite yarn or the Teflon tape in future, also its easier for a good fit as O rings the piston groove has to be correct the first time.

As for grade of aluminium used,I haven't a clue, as its usually aluminium that has come from a scrap bin from the industrial estates.

I was rather fortunate whilst on holiday, a ship yard near by so asked if they had any six inch pipe for a fly wheel, they cut several pieces 20mm wide, and help your self from the scrap bin..

As for the cylinder on my new engine to be made I have bronze ,cast iron and aluminium, bronze I have found difficult to drill 3mm holes 25mm deep as it jambs' up. The cast iron I've used before and have had rust issues, that's why I've used aluminium.

What grade of aluminium do I need, or is cast iron or bronze the best alternative .

Bob.