I have a number of old 40int collet chucks that aren't being used. Either too bulky, missing collets, etc. Rather than chuck them away, I was considering reworking them into something useful, maybe a sidelock holder, flycutter, etc. but keeping the 40int taper. This might involve machining them down, drilling, tapping or welding. In their current hardened state, they aren't machinable, so how should I approach this? Bear in mind, they don't owe me anything. I'm thinking about annealing them and keeping them in an unhardened state as they are only for my own personal use / experimentation and I won't be pushing them hard.
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Agroshield
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The problem with just heating them up in an oxgen-containing atmosphere is that the taper will oxidise.
So either you need a heat treatment facility with an inert atmosphere or you need to protect the taper.
Potentially, a close fitting socket on the taper could do this, blocking all the joins.
Annealing steel, unlike copper, is slightly more complicated than just warming them up. They need to soak at a certain temperature for a certain period of time and then cool at a certain rate.
I think you can buy some paint on material to do this as well as stainless steel envelopes (into which I think you drop something to use up what O2 is there before you seal them).
www.fornitalia.com
So either you need a heat treatment facility with an inert atmosphere or you need to protect the taper.
Potentially, a close fitting socket on the taper could do this, blocking all the joins.
Annealing steel, unlike copper, is slightly more complicated than just warming them up. They need to soak at a certain temperature for a certain period of time and then cool at a certain rate.
I think you can buy some paint on material to do this as well as stainless steel envelopes (into which I think you drop something to use up what O2 is there before you seal them).
LUISO W62 protective paint for annealing | Fornitalia
LUISO W62 - Solvent-free protective paint. Excellent protection for steel components against oxidation during heat treatment up to temperature of 1100°C.
www.fornitalia.com
Thanks for the suggestion but I can't see myself buying any expensive protective paint when this is just an experiment / trying to make use of unused tool holders.
@Fazerruss suggests heating to cherry red, but I'll only be doing that at the end I intend to machine, not the taper end. I wonder whether that will make sufficient difference to any oxidation?
@Fazerruss suggests heating to cherry red, but I'll only be doing that at the end I intend to machine, not the taper end. I wonder whether that will make sufficient difference to any oxidation?
Agroshield
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There is probably some home-brew remedy that would do nearly as well. Perhaps a clay slurry of some sort. Whatever you choose, if it needs a jackhammer to remove after the oven, it is not the correct one.
Maybe a beat up 50 to 40 taper adaptor could provide the protective sleeve.
Even if you try to heat only one end, the heat will travel up the tool - think about how you temper something by heating one end and watching the colours move before quenching.
@Agroshield Following your suggestion I had a look for taper adapters but can find none that are cheap. Remember, I'm trying to use up "junk" rather than invest in new stuff.
Your main concern seems to be oxidation. I could try oil blackening but would that affect the annealing? It surprises me no one appears bothered about removing the hardened state, but it may not matter for a "homemade" tool holder. At least that's what I'm hoping.
Your main concern seems to be oxidation. I could try oil blackening but would that affect the annealing? It surprises me no one appears bothered about removing the hardened state, but it may not matter for a "homemade" tool holder. At least that's what I'm hoping.
