Re: Climb Milling

To Measure backlash:
Travel one inch in the positive direction;
Drill hole number one.
Travel one more inch in the positive direction;
Drill hole number two.
Travel back 1/2 inch, in the negative direction;
Drill hole number three.
Hole three will not be 1/2 inch back from hole number two, by the
backlash amount.

Yes, it is used everytime a motor reverses direction. It applies to
circles - everything.
The motor runs an extra amount, equal to the backlash, for only the
first move after each direction change.

The extra motor movement is just "taking up the backlash".

Backlash can be a combination of gaps and defections (under load).
Gaps are symetrical, deflections may not be and defections are
usually somewhat (nonlinear) force dependent.

A mind quiz: If you have a back and forth moves, does the backlash
accumulate? Or after 10 back and forths are you off from where you
started by 10 times the backlash?

Buck

--- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
> Hi Buck,
>
> I haven't tried any backlash comp for my old Sears/Sherline mill.
I'm
> running MaxNC -PRO, and I think it has a parameter for backlash
comp.
> Can you describe it a little further, and how best to measure it? I
> recently acquired an old "last word" DTI, so I'm thinking I can use
> that. Is it just used every time when a motor reverses? Seems
like it
> would have to be applied when cutting circles (which would be a
hassle),
> as the motors reverse for each quadrant!
>
> Alan KM6VV (going in circles)
>
>
> yahoo@a... wrote:
> >
> > You don't implement backlash compensation by "backing the motor".
> > Backlash compensation works because each time that the direction
is
> > reversed, the software realizes that turns-of-the-motor will not
be
> > reflected in the displacement. Therefore the software runs the
motor
> > a compensated amount more than would otherwise be required.
> >
> > This will not effect the milling direction or interfere with climb
> > milling.
> >
> > Buck
> >
> > --- In CAD_CAM_EDM_DRO@y..., ron ginger <ronginger@r...> wrote:
> > > After all the good explanations and horror stories of the
results of
> > > climb miling and backlash lets hear from the guys that think
> > software
> > > compensation for backlash is a good, or even useable thing!
> > >
> > > Sure, the program can cause the motor to backup to the right
> > > mathematical spot, but while its doing that compensation the
table
> > is
> > > quite free to get grabbed by the tool.
> > >
> > > A great bit of proof why Ive always maintained software
compensaton
> > for
> > > backlash is bogus.
> > >
> > > ron ginger