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| awemawson:
If I get the odd ten minutes I'll try hardening a bit of the same rebar - but things are getting a bit manic here at the moment :bugeye: |
| S. Heslop:
Don't worry about it too much. I'll be testing it myself on... Tuesday? Got the mild steel fully en-rasped. Not the most even of patterns but i'm gonna pretend I was going for random teeth. Hopefully the teeth won't just burn off in case hardening. The chisel kept losing its tip until at about a quarter in it lasted the rest of the way. Kinda odd. Maybe the way it was tempered I was just slowly moving back through different tempering zones as I ground the front away, and eventually hit the one that was about right. Or maybe I found a bit that wasn't full of cracks. I also ground more of a back relief into it to get the teeth looking a bit better (on the far side in this photo so they're kinda hard to see, but they look more like the rasp teeth in photos of real ones). Also gave it a quick test with two sheepish strokes. It's just softwood but the teeth do seem to be cutting. |
| S. Heslop:
Got the teeth in the flat rasp. Had a similar occurrence with the chisel repeatedly breaking at the start, then for the entire last half it lasted fine. I was sort of giving a chance to rest the hammer arm when grinding, so doing all the teeth one after another I eventually found (remembered) that it's better to just let the hammer drop rather than try and swing it. Definitely easier on the arm do to it that way. Had the handle tucked under my armpit and held it right towards the head. Then got it hot and quenched it. I covered it with soap from a bar and it seemed to protect it. I'm still trying to think about how and why that worked. My guess is that it coated the surface with a mix of soot and sodium oxide and kept oxygen away. Edit: That's probably nonsense, any sodium oxide being made would probably instantly react with water in the air/ exhaust. And I imagine sodium hydroxide would be evaporating at that temperature. It protected it very well because I tipped the quenching tank (bit of pipe shoved into a plastic cup) over 3 times, so it was glowing hot for a considerable amount of time. After a scrub, there's still a bit of scale and pitting but the teeth are mostly intact. You can see some cracks on the right hand side. Hopefully it won't cause the thing to shear off at some point. Went all around Consett today trying to find some hydrochloric acid. I've heard it's used in alot of things, as brick cleaner and a pool water additive mostly, but I couldn't find any. For etching it I could use vinegar or citric acid, but I was hoping for something quicker. The funny part is that it'd be quicker to just leave it in vinegar overnight than continue searching for the stuff, but I sort of want to keep a closer eye on the process over an hour or so. |
| chipenter:
for brick cleaner try a builders merchant , for salfuric acid a auto factors . |
| S. Heslop:
Thanks. I don't know why I didn't think of battery acid for sulphuric. |
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