MadModder
The Shop => Metal Stuff => Topic started by: AdeV on September 22, 2010, 12:15:21 PM
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I have a machined piece which I need to replicate. It's made out of a silvery metal, probably some form of cast iron.
Its density seems to be in the 7100kg/m3 region, although it's hard to be precise as my kitchen scales only measure whole grams or 10ths of an ounce. 7100kg/m3 also puts it in the cast iron range, or maybe its "white metal", or something similar...
I've attached a picture of it. It's harded than brass, but seems to be softer than "regular" steel, although it's hard to tell for sure.
Unfortunately, I can't damage this example, so I can't put it on a grinder, or on the lathe for example. It's part of a regulator for a Petter stationary engine - beyond that I know nothing about it. I don't know if the weight of the device is critical, I assume the piston bore is critical but I'm not sure about the length...
Any ideas?
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Certainly not white metal or a similar alloy they would be far to weak for a part like that.
Also I would have thought regular cast iron would be too prone to fracture at the end of teh thread, could possibly be SG iron (Spheroidal Graphite) which is stronger but I'd recon its just steel.
Whats the actual part as this may give a clue to weather the finer machined section has possibly been case hardened.
You could also ask on one of teh stationary engine forums like Smokestak as they may know what that specific part is made from.
Jason
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Is it magnetic?
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Take a clean Q-Tip, dip it in strong vinigar, then swipe the Q-Top along the part. That will propably not damage it. Clean the part ...
Now produce somehow a small (almost) colourless gas flame in a dark room. Then touch the edge of the Q-Tip to the flame.
If the colour of the flame changes to GREEN, then the material is containing COPPER.
Johannes
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Thanks chaps; yes, it IS magnetic, so definitely cast iron or steel. Probably just ordinary steel TBH. Reckon I'll just make one & see what it weighs...
Ta!
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Now produce somehow a small (almost) colourless gas flame in a dark room. Then touch the edge of the Q-Tip to the flame.
If the colour of the flame changes to GREEN, then the material is containing COPPER.
Rubbing alcohol would give you a clean (colourless) flame.
I teach flame tests for GCSE Chemistry - finally a true to life practical example!! Li - red, K - lilac, Na - orange, Cu - green
Good luck and I think u should give it a go for the sheer hell of it - I`ll even send you some nichrome wire for the occasion! :nrocks: :loco:
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Well, I gave it a try with what I had to hand... I have a butane/propane blowtorch which burns with a decent blue flame, not unlike a bunsen burner really. So, first try was a dry cotton bud (slight yellowing of flame); then a bud wetted in vinegar (no change to flame), then wetted in vinegar & rubbed on the metal piece (no change to flame). As that was a bit dissapointing, I tried a vinegared bud rubbed on some copper pipe. No change to the flame :(
Maybe the vinegar isn't strong enough.... it is Tescos 13p/pint special stuff after all...
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If it actually _really_ matters, find a local university physics, chemistry or engineering department with a 'Link Analytical' attachment on their electron microscope. They should be able to give you chapter and verse on the composition down to fractions of a percent in minutes. Won't be able to define heat treatment obviously and if it has been plated, it's the plating that will be analysed.
Richard
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looks mild steel chemiblacked. cast iron has a reddish tinge to it while heat treatable steel are more difficult high to bring to high gloss shine so my guess is mild steel chemblacked
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First test for SG iron is to breath on it then sniff it. If it is SG then it will smell distinctly of acetylene.
Dave.
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Definitely sounds like cast iron which can have a density of 7,100kg/m3, steel is denser so more like 7,400kg/m3 upto 8,000kg/m3 for SS.
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AdeV,
What did it turn out to be made opf ?
Dave
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I never did find out I'm afraid; it transpired the chap only wanted the brass outer piece making, he'd already got the internal gubbins.
I'm pretty sure it was either cast iron, or steel, based on the colour & feel, but once I found out I only needed to make the brass outer, I didn't think much more about it.