On Feb 26, 6:31*am, wrote:
I need to get some parts made, and am going to approach a few of the
local and online cnc machine shops. *I need 300 tubes made, and up to
now I have been doing these on my manual lathe in lower, "as I need
them" quantities.

On my lathe, I was able to hold a .0005 tolerance, which I think would
be called +/- .00025.

Is asking for +/- .00015 too much to ask for a cnc job? Would this be
deemed extreme, or add to normal costs?

Please, only helpful and productive replys.

thanks!

In addition to what others have said, I like to pose the question
another way.

Ask yourself, "What would happen if this part was .010" out? What
about .050" out?" And then make sure to *answer* these questions! Yes,
you'll need a calculator.

Only once you arrive at a limit where your product no longer functions
correctly have you found your *actual* tolerance. Specifying ANYTHING
tighter is costing YOU and your customers money - period.

If you look deeper into manufacturing techniques, there is more to the
story. Based on your question, these topics probably aren't important
to you at this point, however.

Regards,

Robin