Subject: Re: Hardened and Ground Shaft ?

From: [email-masked] (Jonathan M. Elson)
Date: 28 Nov 1996 07:10:06 GMT

Bruce Holder ([email-masked]) wrote:
: Jonathan M. Elson ([email-masked]) wrote:
: : I have quite a few pieces of hardened and ground shaft out of old printers
: : and such.  I tried making a replacement crossfeed leadscrew for my lathe
: : out of one, and was eventually successful, but I had real problems
: : annealing it.  Does anyone know what this steel typically is, and what the
: : annealing procedure is?  And, then, how to re-harden it?

:   If I were starting out with a shaft that I knew was appropriately hard,
: round and straight, I'd see if I couldn't think of a way to grind the
: threads, rather than annealing it and trying to get it hard, round and
: straight again afterwards.

Well, I have a very crude, homemade toolpost grinder. Unfortunately,
when I made it, I never thought of grinding threads, so it has no
provision to tilt the axis of the grinder.  Oops.
					Jon

---

From: [email-masked] (David William Jenkins)
Date: Mon, 02 Dec 1996 21:18:56 GMT

In article <[email-masked]>, Jonathan M. Elson ([email-masked]) writes:
>[email-masked] wrote:
>: In article <[email-masked]>, [email-masked]
>: (Jonathan M. Elson) writes:
>
>: >annealing it.  Does anyone know what this steel typically is, and what
>: the
>: >annealing procedure is?  And, then, how to re-harden it?
>: >Thanks in advance,
>: >    
>
>: A good annealing process for most hardened steels is to heat to red heat
>: and then cool very slowly in a bucket of lime or such. Even better if you
>: have access to a kiln and can draw it back slowly over a few hours.
>
>OK, I've heard of this lime process before.  How big a bucket of lime
>do I need?  Where do I get the correct kind of lime?  Is garden-grade
>lime from the local garden store going to work?  Or does it need to
>be a particular grain size?  Thanks,
>                                       Jon

Just a warning - if you buy a bag of lime from a builder's
merchant, BE CAREFUL!  If it's fresh it may be very active... I
know it's supposed to be slaked (i.e. watered after coming out of
the kiln) but there is a significant risk of a chemical burn. 
Tender, non-bricklayer hands like mine are quite likely to be
hurt, and you certainly don't want to breath the dust, or get it in
your eyes.

In the past I've bought a bag that came straight off the lorry,
and the whole lorry-load was only 1 hour after being bagged.  It was
HOT! I ruined a work-jacket because the dust stuck hard, and
wouldn't wash out of the fabric. Fortunately I was wearing gloves.

If the stuff's been sitting round for a while it's not so bad,
although you still have to be careful with the dust. 

David Jenkins              -- aka --             Lathyrus Computers Ltd
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