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| vtsteam:
--- Quote from: S. Heslop on June 17, 2015, 01:47:34 PM ---I did have a magnet I was using, but it fell into the garden somewhere when trying to anneal the rasps and i'll probably never see it again. Got a few old speakers from a TV i'll probably never use, so I might try borrowing a magnet from those. --- End quote --- Well that's the opposite of what usually happens to me -- I drag a magnet around to find a lost steel part in the grass! Can you drag a piece of your angle iron around to find your magnet? |
| S. Heslop:
--- Quote from: vtsteam on June 17, 2015, 02:06:24 PM --- --- Quote from: S. Heslop on June 17, 2015, 01:47:34 PM ---I did have a magnet I was using, but it fell into the garden somewhere when trying to anneal the rasps and i'll probably never see it again. Got a few old speakers from a TV i'll probably never use, so I might try borrowing a magnet from those. --- End quote --- Well that's the opposite of what usually happens to me -- I drag a magnet around to find a lost steel part in the grass! Can you drag a piece of your angle iron around to find your magnet? --- End quote --- I'd need to be probing the bushes because I think it went down the side of the barbecue. I knocked the screwdriver off that the magnet was stuck to, and it fell off of that. So I still can't get this rebar to harden. Andrew, what do you usually do to harden it? I've been getting it progressively hotter (and past the magnetic point) and quenching in water. Also I did pick up a cold chisel at a second hand shop. I was thinking about grinding it into a shape for this but it's a bit too long, and it seems like a shame to ruin it. So I ended up grinding it into a shape for cutting metal and honed it to a nice edge. Played around for a bit cutting metal with the thing and it's holding it's edge great, even on steel. I've heard that alot of fitting in the past used to be done with files and chisels, but i've never really understood the purpose of chisels since they more or less do what files do. I suppose they can remove material much faster to rough it out? |
| awemawson:
Simon remember that rebar does vary in composition so it is possible that may not harden at all, but it should. Heat somewhat above the curie point then rapid quench in cold water. That will make is as hard as it can be. |
| S. Heslop:
It is hardening I suppose, just not hard enough to survive it's purpose. I might try case hardening it too to see how that goes. Either way, it's a good pair of bars that i'll eventually find a use for. I've been running low on long bits of steel bar. Speaking of bars, I was spending a while wondering about how I might monitor the temperature while case hardening, to make sure I don't melt through the canister. I was thinking about the expensive and complicated ways, naturally, using thermocouples. Then I realised that I could probably just stick a bit of rod down in the fire and pull it out occasionally to see how hot it is from the glow. |
| vtsteam:
--- Quote from: S. Heslop on June 17, 2015, 03:36:34 PM ---Also I did pick up a cold chisel at a second hand shop. I was thinking about grinding it into a shape for this but it's a bit too long, and it seems like a shame to ruin it. So I ended up grinding it into a shape for cutting metal and honed it to a nice edge. Played around for a bit cutting metal with the thing and it's holding it's edge great, even on steel. I've heard that alot of fitting in the past used to be done with files and chisels, but i've never really understood the purpose of chisels since they more or less do what files do. I suppose they can remove material much faster to rough it out? --- End quote --- Yes, they can shear sheet metal held in a vise with a guide, chip grooves, rough down a surface, clean up castings, free steel cores in castings (like my half-nut on the lathe), get in corners you can't get a mill into, cut square where a mill might only be able to do round, split frozen nuts off of bolts and studs, cut off rivets and bolt heads, act as an impact wrench on really big nuts, mark part orientations, etc. This is a really light treatment, but the best i could find for the moment on the inet: http://www.appropedia.org/Cold_chisels |
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