On 01/12/2019 03:43 AM, Roland Jollivet wrote:
On Sat, 12 Jan 2019 at 07:40, Jon Elson <el...@pico-systems.com> wrote:
On 01/11/2019 11:20 PM, Roland Jollivet wrote:
I have an old KTF-30 King Tun Fu drill-mill that I use a lot. But on this
machine, X0Y0 is at top right, as in rotating your graph paper 180deg on
the table.
Since machines and especially CNC machines don't care about orientation
of
axes, why isn't this axis orientation more common? Or is it?
Well, I usually have a vise set up like that, the fixed jaw
is in the +Y direction. So, for those
parts, all Y coordinates are in negative numbers. Doesn't
bother me or the software a bit.
But, my X is positive to the right. So a typical coordinate
might be X+3 Y-2.
Jon
Hi Jon
I'm not sure if we mean the same thing. You would need to swing your vice
around 180 so the handle is on the far side.
I took an image off the net and made up an image
<http://imgbox.com/1gsqFHiu> to show how my axes work compared to a
'conventional' milling machine.
We DO mean the same thing (I think). If the vise jaw is in
the +Y direction, then all part Y coordinates are in -Y.
Now, you COULD swing the whole coord system around so +Y (on
the part) is towards you, and +X is to the left. Since I
usually draw things with +Y up and +X to the right, this
could be confusing. So, I just draw the part with Y=0 at
the top, forcing all Y coords to be negative.
Works fine, leaves the vise handle convenient (and not
likely to hit the machine base.)
So, there's NO REASON you need to use your format, if you
don't mind having negative coordinates.
If stuff matters, you can set up the design so that the
critical Y dimension is at the top.
One thing you want to avoid is having some features machined
with the reference to the edge against the fixed jaw, and
some referenced to the movable jaw. If several parts have
slightly different outer dimensions, then this could throw
the relative alignment between those features off.
Jon
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