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| S. Heslop:
--- Quote from: vtsteam on June 15, 2015, 09:17:33 PM ---4-in-hand rasp --- End quote --- Oh that's what they're called. It's also interesting to hear that about surforms. I was never too confident in them just from the way they looked. If I remember right they come in a few different teeth shapes, some have sort of arched teeth from being punched down, and others have a fair amount of material removed around the tooth which is then bent down but kept rather straight. The second variety (neat story) in particular never seemed so ideal. |
| S. Heslop:
So that big four in hand rasp seems to have gone soft. Or perhaps it was only ever case hardened. I'll probably cut a tang into it and then try hardening the waste to test. Also I've been wondering about case hardening. Perhaps I could put teeth into a bit of mild steel then try case hardening that. If you're using fancy materials like kasenit (which seems to be sodium ferrocyanide, which I still haven't found a source for but i'm sure it must be available. Perhaps I could contact a chemicals distributor. Or maybe even ask my old university chemistry department) would it be enough to protect the teeth from burning away? The thing of sealing it in a tin with charcoal seems fussy, mostly for the risk of burning a hole in the tin. I'm also considering skipping the sandblaster part, and going for an acid etch. I think i've read that they used to do them that way before the days of sandblasting. Finally, i'm also even wondering if the teeth need to be hardened. I'm sure it'd help, but it might be worth seeing how long they'd last if left soft. |
| vtsteam:
questions, questions! Only way to find out some of these kinds of things is to try them! :dremel: Kasenit does seal to the part being heated so doesn't need a container, and also acts rapidly, but to mainly produce a thin case. The pack hardening methods are usually used to get a thicker case. The container wouldn't likely be a tin, but something thicker -- pipe is sometimes mentioned -- one end pipe capped, the other just plugged with clay (likely the obvious explosive safety reason). Or a custom made box and lid, also luted with clay. Kasenit seems to be more than (or other than) sodium ferrocyanide, since it is gray in color. I've read statements that wood actually can wear tools faster than metal -- source lost to memory, so take with a grain of salt. But best to find out by trying, yourself, I always feel. I bet the scraps from your 4-in-hand rasp harden when you try them. ps, can you make a rasp from Andrew's rebar and then harden? I'm going to still plug for forging whatever metal to shape and immediately burying in genuine wood ashes for a few hours, by way of annealing. |
| awemawson:
The original Kasenit used to fuse into a smoothish layer when a red hot item was dipped. The modern stuff seems to have major problems adhering :scratch: |
| S. Heslop:
I've also heard about wood wearing tools faster. I think i've also heard that bits of sand and grit can get embedded in the wood as it grows, more so in some varieties. I'm not convinced it does wear tools faster though. Think about a chisel or a plane iron, which are usually just high carbon steel. Also I did think about making a rasp from the rebar, but I don't think I particularly need a round rasp at this time. So it seems that making case hardening compound is just gonna be another distraction, and a potentially dangerous one too. Is there any particular go-to variety of case hardening compound? I often hear people complain that the new safer stuff isn't anywhere near as good as the old stuff but I don't think I often hear recommendations. |
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