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| S. Heslop:
Butchered that cold chisel, also overheated it cutting the bulk out with the angle grinder, so I re-hardened it. The process knocked the rust off the shank and I can now see it's an Eclipse, made in England. Which as far as I know is good quality. I perhaps should've waited for the boot sale and picked up some smaller, more suitable chisels, but I'm hoping i'll be able to get everything ready to attempt case hardening on Sunday. I left it rock hard but the tip cracked off. Then I over-tempered it I think and it's now back to too soft. I'll have a go at hardening it again tomorrow. |
| S. Heslop:
Really wasted that cold chisel. Just, on a whim, decided to try heating up that original bit of drill rod as hot as I could get it before quenching. I'd say it was getting towards yellow when it wasn't getting any hotter. And it hardened. Maybe all this time I just wasn't getting the metal hot enough, the non magnetic point (and a bit beyond) didn't seem to work. Nor was 'cherry' heat. Been practicing putting teeth into a bit of bar and i'm a little worried about mucking up the real thing, so i'm putting it off. I'm also considering how to best support it. I've got a fair bit of lead i've been thinking about melting into the hollow. Or I could just relocate the vise on top of my Stump and hold it in that. It's arched so i'd assume it'd be fairly stiff if just clamped in a vise. |
| S. Heslop:
I think I now realise why that photo I posted a while back of the chisels had a pile of about 6 of them. They tend to go dull fairly quickly. I spent a bit trying to find a good medium between so hard the tip cracks off and too soft, and I could do about 3 rows on average before the chisel needed regrinding. Got half of it done. I didn't get the orientation right for alot of them, they're all over the place, but I'd blame this on the way I was sitting. Towards the end I went and got a taller chair so the thing wasn't at shoulder height. Also the teeth aren't pretty, some are higher than others and there's quite a long... I guess i'd call it a scoop? I think if I ground the chisel to have more of a back rake it'd produce better teeth but one I had it working at all I was happy enough. Gonna do the other half but I wasn't able to get any fire clay for tomorrow, so I might end up doing it Monday. At the boot sale i'm gonna try and look out for some sort of blower. I usually see a fair amount of bouncy castle blowers and hopefully i'll get lucky. |
| awemawson:
Looks good Simon :thumbup: If the chisel's only lasting a few rows, either the embryo rasp is too hard or the chisel is too soft I reckon. (Says he who's never made a rasp in all his life !!) |
| S. Heslop:
I think it also might be that the chisel steel wasn't water hardening, since I can see a big vertical crack along the front of it. Could be full of loads of tiny fissures that're making some of the tips chip off easily. When I said on average I really should've been more specific and said that sometimes it lasts a couple of teeth before cracking off and sometimes it lasts a whole bunch of rows. Either way, it seems to be working well enough and I haven't found it too much of a hassle to keep touching it up. At some point i'm probably going to use the gas forge again to harden the flat rasp, and i'll give that rebar another go at hardening since perhaps I just wasn't getting it hot enough too. |
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