On Oct 30, 4:09 pm, "Harold and Susan Vordos" wrote:
wrote in message

...
snip---



Arrrgh! - help!!!

Andrew VK3BFA.

Read what DoN said, and work accordingly. One does not set angles on a
grinder using the calibrations provided on the machine. They are for
reference only, considering they are accurate only at the specified length,
and then only as good as the degree of precision in which the headstock and
tailstock are located. Grinders are meant to be adjusted for each and every
operation. Do not trust any of the markings.

The typical cylindrical (or universal) grinder pivots on the center of the
table. It is common practice to use a dial indicator (a DTI works
adequately) to set taper, be it a straight part or a tapered part. One
takes a light grinding cut to determine the status of the taper, then
adjusts accordingly. Considering the length of the part determines the
effect of offsetting the table, there is no hard, fast rule. Adjust the
table a given amount, determine the effect, then adjust accordingly.
Setting taper may require more than a couple attempts----and if you expect
to grind more than one piece, length is often critical, as is the size of
the center in the part.

Do *not* trust setting the angle by comparing to other devices. Unless you
are dead on center, and the part is perfect, you will introduce error that
will not be in your best interest. Use a sine bar or plate to inspect the
grind, adjusting accordingly. Insure that when you inspect the grind that
it is placed at a perfect right angle on the plate or bar.

Harold

Thank you Steve, Don, and Harold. The progressive grind then measure
approach seems logical, and point noted re not setting up to a
reference taper. The Sine Bar - its a word at the moment, heard it,
but no idea how to use one. (But will find out)

Accuracy of taper to Don) - accurate enuff to be a good, non slip fit
in the socket. Its out to blazes now as I can wobble it in the socket
- when I get close, will blue it and then see how close it is. Don't
know how much I have to play with after the initial abortive grind,
the angle is greater than required so MIGHT be able to do it - may
have to start over again (bugger!)

Harold - measuring after each cut - can I leave the job on the
machine, use a micrometer to measure the major and minor diameters? I
note in the reference tables (thanks Steve) that the drawing shows a
fixed length, measured at each end. This does not agree with the ones
I have seen, some are longer than others. I would imagine (???) that
the big diameter
so long as it occurs somewhere along its length, and the small
diameter is the size at the length designated in the tables, then its
ok. I know mine is pretty short, just a few mm projecting out of the
socket (when its cut, of course - not at the moment)

So. Once again, thanks to the members here. The learning curve is
flattening out a little, but still has the occasional deviation to
vertical!

Andrew VK3BFA.