"Bill Schwab" wrote in message
link.net...
snip----
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I think I was making this a lot harder than necessary. Do you care how
much motion there is in the saddle, or merely that a given strip of
metal "sees the entire flycutter"? Assuming the latter, and needing to
face a small block, I did some roughing with a 3/4 endmill and then ran
the flycutter over it (queue drum roll) using the saddle: I got a cross
hatch pattern


Two things should come together. Your indicator, when swept in a circle
that covers the majority of the table surface, front to back, shows little,
if any deviation from your set point, and you get cross hatch when you
machine in both plains, you can assume that your mill is as close as it's
likely to be. As we both agreed, it will never be perfect-----it lacks the
kind of precision required----as do knee mills. If you're happy with how
your mill performs, I'd suggest it's fine. Remember, the amount of error
you see on your indicator translates into how holes lean, assuming your
parts are mounted to the table. Conventional machining requirements
dictate that such things have a common tolerance of .001"/inch, so if the
mill head is within a thou or two over six inches, you're well within
acceptable standards, although I prefer to be closer. I try to keep the
indicator within less than a half thou, but on a knee mill you don't really
know what is correct. Knee sag can be very deceiving.


Unless I am missing something, I plan to leisurely buy another pack of
shims, and _not_ bother using them until I see a problem. Do you agree?

Bill

Yep, I do. Especially considering the fact that you're learning----and are
likely to make mistakes that are far greater than the capability of your
machine. Hope you understand I'm not trying to be rude. It takes lots
of skill to make good parts, and you lack experience at this point. As you
progress, many things that may not be obvious to you now will come into
sharp focus----at which time you may find fault with some of the decisions
you make now---so keep an open mind and consider that you're likely working
with a machine with capabilities beyond the skills you possess as a
craftsman. Hopefully that will change rapidly. That's really what it's
all about. Truth is, you'll know when the machine isn't up to your
standard, or requirements.

I think you're doing fine, Bill. What impresses me more than anything is
your ability to be told, and that you listen. Makes it worth my time to
try to help.

Harold