Thursday, March 19, 2009

Craft adventures

The pair of scissors on the left were bent and no longer worked as scissors. I heated and unbent the handle near the pivot point using a small Ace hardware propane torch kit; the kind that comes with a 14.1 oz propane bottle. There have been a few "gremlins" in the process; like the first torch I bought didn't have a hole drilled in the end, just a solid brass end. I told the clerk it would make a good practical joke when we returned it. Anyway I put the scissors into a vice and just heated one area until it turned red, then turned off the torch and bent it with a pair of vise grips, but pliers would have worked just as well.
I had intended to straighten out the handles all along, so I just kept heating and bending them back to get the hand loops back and out of the way. Interestingly enough, the handles cooled and became what I would call, grass-stem straight. I wasn't aiming for perfectly straight anyway, but once cooled and when I played with the scissors, snapping them open and shut a few times, the handles started to twist by themselves. Trippy. I had read about how heating and bending metal puts internal stresses into the material as it cools. It was like the steel wanted to go a certain way, and just by handling it a little, when it cooled all the way to room temp it went there. I have also read that in order to deal with this, one has to anneal the steel after working it in order to relieve these stresses. Likely it's even worse than usual because I only heated small sections at a time and bent them rather than heating the entire peice at once (which I can't do yet). Annealing in this case means to take the hardening out of metal by heating it up... and here I will quote liberally from wikipedia:

"Carbon steel is heated to approximately 40 °C above Ac3 or Ac1 for 1 hour; this assures all the ferrite transforms into austenite (although cementite might still exist if the carbon content is greater than the eutectoid). The steel must then be cooled slowly, in the realm of 38 °C (100 °F) per hour. Usually it is just furnace cooled, where the furnace is turned off with the steel still inside. This results in a coarse pearlitic structure, which means the "bands" of pearlite are thick. Fully-annealed steel is soft and ductile, with no internal stresses, which is often necessary for cost-effective forming. Only spheroidized steel is softer and more ductile."

So, getting the true signifigance actually gets taught better by doing. It was pretty fun having steel twist itself into a new shape in my hands, felt like it had a mind of it's own. I did manage to anneal some steel in my flower-pot oven already. People tell me that blacksmithing is a slow process, and I am getting some sense of that.

This started life as a pair of forged scissors from China. I understand you can buy them for about three bucks. From the photo at the very top you can see that they had a very graceful curve to the handles which must have been put there by bending over a form in one motion while they were red hot. My current torch will only heat a small area at a time. I tried to trap the heat by stacking firebricks, but it didn't help much. This after reading about something called a bean can forge . My firebricks are the denser type; they look and feel like sandstone. They appear to absorb a lot more heat than they reflect back. I understand that they last a long time though, and they were only two bucks each. The other type of firebrick which I have seen elsewhere are very frangible, light weight with a consistency sort of like styrofoam. They are reported to have a higher r-factor. I bought the only kind available locally. Oops. There's this stuff called kaowool which potters use; it's a sort of spun-ceramic blanket, then they coat it with some other stuff called itc-100 which is claimed to reflect 98% of the heat energy. I don't have any; the itc-100 is about $30 bucks a pint and I had really intended to do the forge project on a shoestring budget. However wasting fuel would quickly drive up costs, so there's a point wherein being too cheap doesn't pay off. As it turns out the very first thing I wanted to do is called forge welding, where the material has to be much hotter in order to join two peices together. So far I can barely put a dent in metal, let alone weld it.

We've now spoken with a couple of guys who are expert welders. One had a long career doing welded art peices. He doesn't want any publicity because he's retired now. I'm noticing the welders tend not to forge, blacksmiths tend not to weld, and metal casters tend to stick to casting, doing neither welding nor any forge work. Oh yeah, and glass blowers probably don't do much metal forging either, even though they could probably do so pretty easily. Hmmm. One of the local guys with an art metal shop in Show Low mentioned how quickly his computer controlled plasma cutter could perform tasks ( in seconds ) versus hours. Mostly I have been getting a history lesson with all my research into this stuff.

I think we watch shows like "Terminator" because it's such a literal picture of what we're doing to ourselves with technology. A lot of the hand made things you see are made overseas where low-tech labor is cheap enough that you can't beat the final product with a lot of high tech factory machinery. Around here there was a big problem with Native American craft products turning out to be made in China. I think I'm re-working a chinese made pair of scissors
( hand-forged, no less ) to give me more of an appreciation for hand made products. It may be slow and laborious but you learn a lot and it stays interesting. Beats factory work.

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