Re: Re: Long term Z axis problem

> Hello,
>
> If the step polarity is wrong then you would likley have unreliable
> stepping no matter what the step and direction widths are.
>
> Try changing the step polarity then experiment with the step width or
> delay.
>
> Tom Hubin
> thubin@...
>
> ***************************************

Tom,
This was amongst one of the first things we checked and it was marginally better in one position.
We then went thru the whole range of step and direction width finishing up at 20 usec for both which is what it's on now.
Even trying all different setting we had very little difference in the results but just swapping the drive has cured these without having to re-do any settings.

What it doesn't answer is why a second drive went after 2 days for no reason and at no point did it take a fuse out.

John S.

>
> John Stevenson wrote:
> >
> > > John You mention that you are using the G210 on the Z axis and you
> > mention
> > > that the problem went a way when you shifted to the chinese drivers.
> > One
> > > factor why the G210 may exhibit lost steps may be due to the
> > software
> > > direction change timing was be too short. I would increase it if
> > possible
> > > to at least 5 usec
> > > Dan Mauch
> > > low cost stepper and servo motors.
> > > cases for Gecko drives
> > > kits and assembled 3-4 axis drives
> > > www.camtronics-cnc.com
> > > www.seanet.com/~dmauch
> >
> > Dan,
> > That was one of the first things we tried.
> > I had Ian Eagland helping who is the UK Ahha agent and is very
> > knowlegable on this controller.
> > If I remember right we tried from 2 to 25 usec with no difference.
> > I'll check what it is on now as it wasn't touched when the Chinese
> > drive went on.
> > Today was the last day on this job, so far today it has drilled 7,800
> > holes in 5mm steel plate ans still on the Z zero mark.
> > Before I had to reset the Z every 4 playes or 1700 holes as it was 10
> > to 15 thou out.
> >
> > John s.
> >
> > > ----- Original Message -----
> > > From: "John Stevenson" <john@...>
> > > To: "CAD_CAM_EDM_DRO@..." <CAD_CAM_EDM_DRO@yahoogroups.com>
> > > Sent: Thursday, September 07, 2006 2:43 PM
> > > Subject: [CAD_CAM_EDM_DRO] Long term Z axis problem
> > >
> > >
> > > > The machine is a NC5 Beaver mill, about the same size as a series
> > II
> > > > Bridgy.
> > > > It's on type 42 steppers direct driving 5tpi screws and it was
> > made this
> > > > way, it's not a conversion.
> > > >
> > > > For any years it ran on an old bi level driver with little or no
> > trouble
> > > > except for old and dated components.
> > > > When the last driver borad went pear shaped I changed over to
> > modern
> > > > drives and settled on Gecko 210's running at 10 microstep.
> > > >
> > > > X and Y have alway run OK but the Z axis has always lost postion
> > > > 'slightly'. on a normal small part at the finish I could be a thou
> > or two
> > > > short of zero.
> > > > It's never bothered me as nothing I do is that critical in Z.
> > > >
> > > > On some parts where I have to drill literally 1,000's of small
> > holes I
> > > > could be 15 to 20 thou short, again not a problem as these are
> > thru holes
> > > > and there is enough clearance both sides.
> > > >
> > > > The machine runs AHHA software which is very good as it's
> > customisable in
> > > > many ways.
> > > > Different settings were tried to try to cure this, pulse width's,
> > leading
> > > > edge, trailing edge etc. Marriss was consulted but he put it down
> > to a bad
> > > > motor even though I had tried three different ones.
> > > >
> > > > Last weekend I had the misfortune to crash the machine, my fault I
> > chose
> > > > the right tool but wrong offset and stuffed the 20mm cutter into
> > the vise
> > > > jaw.
> > > > Not a bad crash as things go, 30 thou cleaned the jaw up on the
> > grinder
> > > > and the tool was resharpenable without taking loads off but it
> > took the Z
> > > > Gecko out.
> > > > Fuse was Ok but all the mosfets are burnt.
> > > > OK, my fault, hands up and learn from the experiance.
> > > > Replaced it with a brand new Gecko 210 and away we went.
> > > > Ran the rest of Sunday and all day Monday, switched off Monday
> > night and
> > > > rezeroed the Z as usual, 10 thou out.
> > > > Switched on Tuesday morning, hit start and no Z moves, checked the
> > drive,
> > > > no light on but fuse OK and it had 62 volts to the drive ?????????
> > > >
> > > > Why ?? running OK on the night, did nothing and no drive in the AM
> > and
> > > > fuses intact. Internally the drive shows no damage.
> > > >
> > > > No spare drives left, new or secondhand but I did have a couple of
> > 80 volt
> > > > 7.8A Chinese drives handy.
> > > > Wired one of these in, same motor, same fuse and everything and
> > did a
> > > > dummy run of the program to try it out.
> > > > Worked OK but when it had finished the Z was back to zero.
> > > > Since then the machine has done 8 hours of continious drilling and
> > hit
> > > > zero at every finish.
> > > >
> > > > Nothing has been changed as regards setting, ramp, acceleration
> > etc other
> > > > than the steps being altered as these Chinese drives are 8
> > microsteps
> > > > instead of 10.
> > > > The Gecko's had the jumper set to the 42 motor setting but the
> > Chinese
> > > > ones don't have a setting.
> > > >
> > > > Just have to wait and see what the long term results are.
> > > >
> > > > John S.
> > > >
> > > >
> > > >
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