> I have used a lot of hardware-store taps over the
> years and most of them are rubbish sutible only for cleaning
> up existing threads in soft metal.
Which presumably is exactly what we're talking about here. The very few
hardened fasteners on a TR should be replaced if the threads are damaged,
IMO. And while the need to fabricate parts during a TR6 restoration does
sometimes arise, hopefully it's not often (since the hand-fabricated part
will not be a match for the "correct" part).
As I understand it, high speed steel is appropriate for situations where the
cutting edge potentially gets hot enough to soften carbon steel; which
generally means a power tool is involved. Otherwise, ordinary carbon steel
actually holds an edge better. Hand-tapping would seem to usually fall in
the second category ... although I must admit, I finally wore out a 30 year
old carbon steel die a few days ago, cutting threads on drill rod with it.
But if it didn't have a couple of broken teeth, I'd sharpen it and go on.
> Just don't use it in cast iron. :-)
I'll bite, what's wrong with using cutting oil in cast iron ?
I very rarely cut new threads in cast iron anyway; and generally don't
bother with it when I'm just chasing old threads; but the few times I've cut
new threads in cast iron, the cutting oil seemed to help.
Randall
(Tedious but unavoidable disclaimer follows)
CONFIDENTIALITY. This electronic mail and any files transmitted with it may
contain information proprietary to NavCom Technology, Inc., or one of its
affiliates, and are intended solely for the use of the individual or entity to
whom they are addressed, shall be maintained in confidence and not disclosed to
third parties without the written consent of the sender. If you are not the
intended recipient or the person responsible for delivering the electronic mail
to the intended recipient, be advised that you have received this electronic
mail in error and that any use, dissemination, forwarding, printing, or copying
of this electronic mail is strictly prohibited. If you have received this
electronic mail in error, please immediately notify the sender by return mail.
_______________________________________________
This list supported in part by the Vintage Triumph Register
http://www.vtr.org
Triumphs mailing list
Triumphs@autox.team.net
http://autox.team.net/mailman/listinfo/triumphs
|