"Nitrided Steel" o.O?

[madwilliamflint]

Hey guys,

Been lurking for a while as I've been focused on other things. But I came across something I'm perplexed by.

An instrument, much like a steel drum in spirit. (So, sheet steel banged into a dome, then notes hammered flat into it.)

In the discussion about making the things they're very "hand wavey" about the steel they "came up with" with the help of some German manufacturer.

Most notably they describe 'nitride hardening' the steel once in form in a 600 degree C chamber with an ammonia atmosphere for "a number of hours."

Now, as I've decided I want to make one of these things I've got to ask.

Does that make ANY sense?

Or are they just heat treating/hardening the thing since it's 0.032" thick?

I'll try to find the original reference for the insomniacs among us.

[Ian B]

Will,

At the risk of being called a closet wikiphile, try this: http://en.wikipedia.org/wiki/Steelpan

Seems it was the Swiss who nitrided them. Lots of other sites written by experts in things other than mettalurgy will tell you to heat the steel over a fire and then pour water on it - apparently the expansion and contraction this causes hardens the steel. Hmmm. My guess is that hardness has been seen as a desirable quality, and the ever-resourceful Swiss then tried to apply some engineering to the problem and do a proper job of hardening the metal. You're probably just as well off roasting it on a barbecue for a few hours and then chucking a bucket of water over it.

Google "steelpan" - lots of info, some might even be correct...

Ian

[lazlo]

What are steel oil drums made from?
Nitriding only works on alloys with chromium and molybdenum (which form nitrides) i.e., Chromoly, Nitralloy,... You can't nitride plain carbon steel.

That seems awfully high tech for a Caribbean drum

[topct]

This is interesting, whats the fire doing? You would not want the drum head to ring like a bell for this type of metal drum. The notes would loose definition. I can raise the pitch of a harmonica reed by shortening. I can lower it by stiffening. He uses a solid state tuner and a hammer to do the same, that's grand.

http://www.youtube.com/watch?v=mQu5Unc_TNY

[lazlo]

This is interesting, whats the fire doing?

Annealing/stress relieving the steel. I looked it up -- oil drums are made from cold rolled mild steel.

[John Stevenson]

What happens if you play them with de-oxygenated copper speaker wire as drum sticks ?

[topct]

Turn it upside down,

http://www.youtube.com/watch?v=mQu5Unc_TNY

[madwilliamflint]

Will,

At the risk of being called a closet wikiphile, try this: http://en.wikipedia.org/wiki/Steelpan

Seems it was the Swiss who nitrided them. Lots of other sites written by experts in things other than mettalurgy will tell you to heat the steel over a fire and then pour water on it - apparently the expansion and contraction this causes hardens the steel. Hmmm. My guess is that hardness has been seen as a desirable quality, and the ever-resourceful Swiss then tried to apply some engineering to the problem and do a proper job of hardening the metal. You're probably just as well off roasting it on a barbecue for a few hours and then chucking a bucket of water over it.

Google "steelpan" - lots of info, some might even be correct...

Ian

HA! We've come full circle quickly enough. You've found the reference I'm working from.

I keep looking at the steel drum tuning videos and while final tuning seems to qualify as an "interesting process" in that I may hit a dead end when I get there, the rest of the manufacture seems to generally consist of a hackish "yeah rightaboucheer" mess.

Here's the desired end state in action: Hang Drumming (well, ok, That's Dante "in action" but you get the drift.)

Anyway I've got a bunch of off cuts of different thicknesses en route to noodle around with and see what happens.

[topct]

The tuning is very important and I think would be the hardest to do. His drums are tuned to work with each other and although my first guess is he can play what he is playing on purpose, if he were to miss you might not know it. The rhythm and the scale of notes on the drums are his secret.

You might seek out someone with a hang drum and see if they will let you tap on it. Unless you are trying for a melody, you can't miss. Could be very addicting.

[madwilliamflint]

The tuning is very important and I think would be the hardest to do. His drums are tuned to work with each other and although my first guess is he can play what he is playing on purpose, if he were to miss you might not know it. The rhythm and the scale of notes on the drums are his secret.

You might seek out someone with a hang drum and see if they will let you tap on it. Unless you are trying for a melody, you can't miss. Could be very addicting.

My first impulse was "What? It's a bowl with some flat spots dinged into it. Diameter of the flat spots are proportional to pitch in some deterministic way.." But the more I look at them and the more I read about the physics of tuning them, the more I think that perhaps my eyes are bigger than my stomach on this one.

Who knows. At this rate I'll have prototypes in a couple weeks.

Worst case scenario I figure I'll make some of those "halo" tongue drums.

[Boucher]

I once toured a plant that manufactured big chain sprockets. They had an interesting mechanized flame nitriding process used to harden the wear surface. Rumor has it that some old blacksmiths quenched blades in horse piss that is high in nitrates. Could you heat it and use a casehardner?

[lazlo]

Rumor has it that some old blacksmiths quenched blades in horse piss that is high in nitrates. Could you heat it and use a casehardner?

http://bbs.homeshopmachinist.net/thr...bstances-abuse

Urine quench doesn't add nitrates. It's just a brine quench -- quite a bit faster than water quench:



Theophilus wrote that the urine from a red-haired child or a goat fed ferns for three days was best

[John Stevenson]

Some old English texts state that the blood of a Liverpool virgin is best, however the last known sighting of one was in 1924 on a trip to the Cadbury chocolate factory at Bourneville.

This has caused the Tifiepedia definition to be altered to read :-

"Liverpool Virgin"
Any female under 13 who hasn't been f^*ked much "

[madwilliamflint]

I'll say one thing: I do suspect that the introduction of ANY reasonable precision to this process will make the mystique of tuning evaporate entirely. I don't think it'll make it easy by any means. But when you start your form by bouncing a friggin ball in the lid of an oil drum, you're bound to need some friggin finesse to get the thing to sound right.

I call shennanigans.

[Bob Fisher]

These drums have been kicking around the islands for a long time. I really doubt that there is any sofistication in their construction. It's probably a passed down skill and pretty much done by ear. All that aside, I love steel band music! Bob.