"Ed Huntress" wrote in message
...
"Martin Whybrow" wrote in message
news
Further to my last post (Material for clamping wedges), I've now
determined
that the original parts were case hardened steel.
I will be making the parts up soon, but I don't know what grades of
steel
can be case hardened; the commonly listed steels for case hardening are
EN3B
(SAE 1017 or 1022) and EN32 (SAE1016), but these are not readily
available
in small quantities (600mm / 2'). I can obtain EN1A (free machining mild
steel, no direct SAE equivalent) or EN8B (closest equivalents are
SAE1040
and SAE1038) from model-engineer-friendly suppliers, but I am unsure if
these can be case hardened. I plan on using Kasenit case hardening
powder
to
harden these parts. Can anyone enlighten me?
Martin.
Sticking to ordinary grades of low-carbon steel, I have yet to find one
that
wouldn't take a decent case using Kasenit, and I've been using it for
about
40 years.
I haven't *intentionally* tried to harden medium-carbon steels, such as
1040, but I'll bet it would be reasonably satisfactory. I've probably done
it without knowing what grade I was working with.
What are you trying to achieve? A very thin case, or a thicker one? Thin
cases are much easier and put less stress on the steel. So you don't have
to
bother about tempering them.
--
Ed Huntress
Thanks for all the replies.
It hadn't occurred to me that the reason low carbon steels are used for case
hardened applications is that the core metal will remain in a soft state and
therefore add strength to the part; it's obvious now I think about it.
The application is for a clamping wedge for my milling machine's swivel;
it's a 3/4" rod, narrowed to a 3/8" flat section at one end with an 18.5
degree taper on the lower narrow face. The tapered section passes through a
slot in the table clamp (imagine a T bolt with a rectangular slot through
the shank), the lower edge of this hole has a matching wedge on the lower
face so that as the rod is driven through it, it clamps the swivel onto the
saddle. The clamps appear to be cast and are relatively soft; the clamping
wedge is hardened to prevent it galling against the opposing wedge surface
in the clamp and therefore probably only requires a thin layer of case
hardening.
Martin
--
martindot herewhybrowat herentlworlddot herecom