Saturday, July 29, 2017

ASM Summer Camps - 2017

The summer ASM teacher camp schedule is up and posted on the ASM Foundation website - link here.

The teachers camps - in case you weren't aware, and the majority of you folks visiting here are probably familiar if not intimately so - are phenomenal. Check out the testimonials and news reports from the camps here.

Sunday, July 9, 2017

Railroad Thermite Welding: Europe & Russia

Yup, dramatic music at the beginning. That'

In addition to possibly watching this with the sound off, I'd also suggest turning off the annotations because they're just annoying ads for other videos.

There's a pretty stunning, handheld blowtorch at 0:30. All those tiny flames makes me wonder just how frickin' hot the torch gets.

Most of what we get in the video - including the phenomenally bright fire at 1:55 - is pretty standard railroad, thermite welding.

The animation at 2:09, however, isn't standard. It's a great cutout view of what's happening within the thermite weld.

After that, there isn't much more than three barely  different versions of thermite welding. The first ends around 3:05. The second ends around 5:50, and the third wraps up at about 8:25.

Really, the animation at 2:09 is the only new thing to see here.

Wednesday, July 5, 2017

The History of Iron and Steel

I'll be right back. I'm going to refresh myself with the video Material Properties 101 before I watch the rest of this. Luckily, your friendly neighborhood blogger already linked to that video, too.

The video is a great exploration of...

  • the differences between wrought iron, steel, and cast iron
  • the processes in purifying iron ore - especially highlighting other videos that show primitive ways of doing this in modern times
  • blast furnaces, used to purify iron ore in modern times
  • producing steel in various ways - including via a puddling furnace
  • the Bessemer converter to produce steel

The video is, I think, too long to show in class unless your students have a better attention span - and tolerance for foreign accents - than mine do.

The video shows that it's 13:35 long, but it's really about ten minutes followed by a plea for a charity donation for the last three and a half minutes. The charity donation link is no longer accepting donations.

At 2:38 there's a hiccup in language. He says wrought iron is less than 0.8% carbon, but his graphic shows that it's less than 0.08% carbon. Wikipedia agrees with his graphic. Decimal places are hard sometimes.

Alcohol Reducation Raku with Shawn Felts

Raku is pretty stunning.

I don't know that we need another raku video on this blog, admittedly, but there's something unique here that's worth seeing.

  • I very much dig that the video here opens with a comment that Shawn Felts worked at Funke's Fired Arts (the ceramics store here in Cincy that we use for our supplies at Princeton HS). They've changed ownership and names since Shawn worked there, but they're still a good place.
  • There's a whole lot of talking to start the video meaning it's really informative, but it would be awful to show in class. There's no way that students are going to pay attention until probably 19 minutes in - when the fire starts.
  • I appreciate the full beard and the confidence with it around the fire.
  • At about 13:40 he mentions that raku pottery all fades to black (oxidized) over time. I've not noticed that in the past, though I've only done raku for about a half dozen years. Is that fading anything that anybody has seen in their experience? I think our glazes might encase the reduced metal in a thicker glass layer, so that may not be the case for our process.
  • Holy crap that furnace ramps quickly. He goes from room temp to 1750 F in about twenty minutes. That's a fast, frickin' ramp rate.
  • So much of this seems like he's doing it because he's done it before and it worked. Comments like that the alcohol 'soaks into' the glaze make me think that the science is a little iffy in some of his explanations.
  • It's at about 18:50 that the piece finally comes out of the kiln. 
  • I'm still very much unsure of how the glazes work and all the science of raku. With my understanding of the science, the repeated sprays of alcohol are doing almost nothing because it's just burning off each time. Yes, oxygen is being used up and copper is reducing, but that is immediately lost when the hot pot is allowed to then sit in the air before being moved into the sand under the glass bowl.
  • The glass bowl is the big reason why I'm posting this video. We actually get to see the reduction (at 21:15 with the last shot of alcohol into the reduction chamber), something that we never get to see because our reduction chamber is entirely opaque (metal paint cans.)
  • I appreciate Shawn's impatience, something he mentions at 25.45...and again at 28:05.
  • I wonder how much the time jumped at 24:15, because there's a clear edit. How long was the piece in the reduction chamber cooling down?  
  • Can we talk Bernoulli's Principle when he blows the air in at 24:44?
  • Holy crap...the color change right after the blow of air is a great money shot for the video. Actually seeing the reduced copper (shiny penny) change to oxidized copper (shiny blue, purple, green) is stunning.
  • Does the spray with water just cool the glaze enough to not allow oxygen to move into or out of the glaze? That's my understanding but doesn't quite fit with Shawn's explanation.
  • More edits at 26:14...27:30...30:35...31:35
  • Who are the people watching this video? They don't look like they're dressed to get involved. Maybe this is just an open house situation.
  • I never knew what grog was (28:40). I knew our raku clay had a bunch, and I kind of knew why (decrease thermal shock). I just never knew what grog was - already fired, pulverized clay so it doesn't shrink. 
  • Shawn mentions at 28:50 that he could dunk the raku piece in water without it shocking but almost chuckles as if he wouldn't want to risk it. Hey, that's exactly what we do with our pieces.
  • Some alcohol jokes at 30:10 - talks about the fumes tasting like rubbing alcohol and that Shawn's more a bourbon man than he is a rubbing alcohol man.

Tuesday, July 4, 2017

Shear Pins are Smart (They're Mechanical Fuses)

I'm not a car guy.

I'm even less of a tractor guy.

I pay to get my oil changed, and I'm happy to do it.

So, when it came up in our summer camp discussions that quenched metal would be useful for shear pins, I wasn't really comfortable with doing more than just nodding and smiling. "Yeah, shear pins...exactly."

Then I had to go look up what shear pins are.

Now, here's my understanding. Shear pins are hardened steel, typically quenched steel. Sometimes a rotational part of the machine - the lawnmower blade, the snow-blower - gets blocked and stopped. There's a driveshaft feeding rotational energy to that blade, however. Something in the chain  then has to break because the motor is continuing to try adding more rotational energy to the now-stuck blade.

If all the parts were equally tough, the break would take place randomly.

Instead, the engineers intentionally put in a weak spot, a quenched piece of metal called a shear pin. The intent is for that piece to be where the break happens because it's the cheapest part of the chain. It's better to break the cheap part than to maybe break one of the expensive parts.

Man, it's almost like people are smart.

I'm happy to say that I'm getting smarter every day.

Solid-Liquid Phase Diagrams: salt solution

Trigger warning: One of the linked articles addresses tie lines.

In our summer workshops we have a demonstration (amateurishly filmed versions can be seen here and here) that is designed to show and introduce the idea of a eutectic point, the mixture of two pure substances that has the lowest possible melting point.

In the workshops, we use either a tin-bismuth or lead-bismuth mixture. The teacher campers produce 'spots' in varying alloy compositions from 100% tin to 100% bismuth. We then melt the spots on a pancake griddle and produce a eutectic graph.

All of that is explained brilliantly on this page (for the lead-tin mixture). In our summer workshop, we don't remotely address tie lines, through which the exact composition (what % of the liquid is tin versus lead) of the 'slushy' mixture can be determined. That's beyond the scope of the summer workshop, but it's highly relevant for metallurgists.

One of my campers a couple of years ago, however, brought up the connection of the bismuth-tin eutectic to the mixture of salt and water, a mixture of which melts at a lower temperature than does either pure substance. At the time, I acknowledged that this was exactly the same idea and moved on.

Since then, however, I hunted down a salt-water graph similar to that for the bismuth-tin mixture.

Lo and behold, such a graph exists, and there's even a similar article addressing how this is, indeed, like the lead-tin/bismuth-tin eutectic.

It's just the same graph as the one at the top of this article...
I'm so very happy to have found that.

Seriously...I actually am.

Why are you looking at me like that?

I'm nerdy like that.

40 Cool Things to 3D Print That are Actually Useful

That actually does look useful - maybe not for a classroom setting but for an office setting.

It's one of the 50 Cool Things to 3D Print Which Are Actually Useful, each of which links to the plans.

Get printing, folks.

But don't ask for tea from your drink printer.