Re: [CAD_CAM_EDM_DRO] Long term Z axis problem

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

----- 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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