On 09 Dec 2004 20:47:54 GMT, oEmails (Dave Baker)
wrote:

Subject: automotive engine boring on a mill
From: Anthony
Date: 08/12/04 23:54 GMT Standard Time
Message-id:

(Dave Baker) wrote in
:



snip all the rest

This thread is about the boring and honing of engine blocks for engine
reconditioning. I don't know why you and Robin keep trying to drag it
into an argument about production line metrology which has nothing to
do with the needs of a man trying to bore and hone the one engine he
has in front of him at the time so that the bores are X thou bigger
than the one set of new pistons he has in front of him at the same
time.

BTW....since you obviously didn't read enough of my post to answer my
question, and you brought the subject up again here...Just where (on the
piston) are you measuring the diameter of the piston to get the bore
size?

That's easy. You know how to accurately count the number of sheep in a field?
You count the legs and divide by four. Well on the same principle, to measure a
piston skirt you measure the i/d and add twice the skirt thickness

I understand there's no particular reason you ought to know what I do or that
I'm one of the leading specialists in engine design and theory in the UK (you
probably haven't bothered to read my website) and certainly none to know that
I've designed and made pistons. By that I mean designed and made the casting
moulds, the initial mandrel to hold and rough turn the machining datums into
the casting, researched and specified the alloy, written the computer programme
to calculate the major dimensions, section thicknesses and mass, specified the
barreling and ovality, designed an elliptical turning system to produce the
skirt profiles, researched and specified the pin bore to pin clearance and the
methods of achieving it (fine bore followed by roller burnishing, fine bore
followed by honing, reaming and/or followed by either), researched and
specified the pin material, surface hardness and dimensions, researched and
specified the ring spacing and ring groove to ring clearances.

Most of the machining was done by a friend with CNC equipment to my specs but I
did the initial rough turning and datum points for all the castings and to
prove a point made a set from scratch on my Colchester Student including making
the ring grooving tool and turning the ring grooves in, reaming the pin bores
and oval turning the skirt profiles, building the test engine and then running
that as my daily driver.

So please, no bloody stupid room 101 test questions about where the datum point
for measuring the o/d on a piston skirt is because if you really want to get
into engine theory with me I'll blow you out of the f***ing water.
Yeah Dave, but what do you really know about making pistons. I see,
from you post, that you didn't mine the bauxite, or even collect the
beer cans to melt down. You just specified the alloy. Sheesh!
Cheers,
Eric R Snow