Re: [CAD_CAM_EDM_DRO] move error in MACH3

Well, this is embarrassing. To quote John Wayne, "Life is
hard......It's harder when you're stupid" ufduh.... but I now know the
problem...

Last night I decided to check the backlash for myself, and it is 0.045"
and was set at 0.0" in MACH and observed but not understood on Sat with
repeated moves in MDI that were coming up 0.045 short of target (moving
back and forth, and thus experiencing backlash).

So disappointed in my plastic nut! I am pretty sure we measured this at
just a couple thousandths backlash when we put it together several
months ago.

So has anyone had luck with plastic antibacklash nuts on ACME threads?
Again, I thought I was good with just a threaded plastic piece, but now
I think I'm going to disassemble, slit it perpendicular to screw axis
and use screws to pull the two halves together. I really don't want to
through several hundred more $$ at this X2 in the form of ballscrews,
cuz it is really too small for what we need to do. I could live with an
X3 sized machine, but...

THANKS for ALL your help!!
Chuck

On 12/3/2012 11:21 AM, Jon Elson wrote:
>
> chuck merja wrote:
> > BTW - as I said I have some thoughts about how to accurately measure
> > longer moves, but I'd love any suggestions...I have 6" dial
> calipers, 6"
> > precision parallels, 123 blocks, a 3" vise, a laser "edge finder", real
> > edge finder, a machinists precision square, and maybe a precision angle.
> >
> >
> A stack of gage blocks set against a precision square that has been
> aligned with the
> axis and clamped is the best way. But, maybe you could do the same with
> your
> 123 block. Mount the indicator to the head, and align the square to the
> axis and
> clamp gently. Now, you can zero the indicator against the square, and then
> insert the 123 block in 3 different positions, to make measurements at
> 3 values. With two 123 blocks, you can get all the way up to 6".
> Measure with the table moving toward and away from each reading, and
> put it all in table form, and something useful ought to come from that.
>
> I don't know Mach, but maybe you have a lot of backlash, but the person
> who set up the backlash setting is covering that up with Mach so you
> don't see it in MDI, but maybe backlash compensation is not activated
> in jog moves.
>
> Jon
>
>



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