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Messages - moorea21

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121
General Mach Discussion / Re: dying motor(s)?
« on: January 09, 2015, 11:17:23 AM »
I rechecked all wiring, substituted in a spare motor, and set the acceleration to 1/50th of its previous amount; that last change solves the problem, but leaves me with a very very slow machine. I don't think the motor is up to the task, maybe I need it to move too fast for it to maintain enough torque to avoid missing steps. Need more current, so may need to upgrade motor, maybe driver too. More money will need to be spent, it seems...

122
General Mach Discussion / dying motor(s)?
« on: January 08, 2015, 05:19:20 PM »
I have 2 nema 23 motors (X,Y), one of which (Y) started 'slipping', (for want of a better word) today. Its holding torque when not moving seems to be a good as ever, but when the y axis goes some distance, then stops and reverses, it makes a sound which was familiar to me when I ran it off a much lower current when testing. The motor has worked fine on the odd occasions I've used the machine in the last 4 or 5 years, I recently mothballed the machine, moved it, and reassembled it, and suddenly this happens.

It's a belt driven axis, I checked and rechecked everything there that could slip, nothing wrong.

Running the motor at 1/6th the acceleration didn't help, in fact, when I set it back to full acceleration, it had got worse.

The x axis motor, which works fine, feels very stiff and notchy to turn by hand, off the machine.

Are either or both on their way out? I hope not. I hadn't expected it to be such a sudden demise if so. I have a spare motor, which may not be that good either. I had expected a longer lifespan; the Z axis is not light by any means, and the Y axis does do a lot of small moves, and a few large ones. Also, the Y axis motor's bearings take the full side force of any acceleration/decceleration, although on this machine, there are no cutting forces or sideways forces for it to cope with. But as I said, the Y axis motor feels smooth to turn by hand., it's the X that's 'notchy'

Could it be a Mach problem? I doubt that, so I haven't reloaded Mach to test that idea.

M21

123
General Mach Discussion / Re: Gcode to zero Z axis during run
« on: April 14, 2014, 02:25:21 PM »
That's good news! No complicated hacks needed.
Thanks Gerry.

So I can use G28.1 or G31?

124
General Mach Discussion / Re: Gcode to zero Z axis during run
« on: April 14, 2014, 01:12:41 PM »
Okay, it makes sense, apart from the fact that I can't see a way (in the manual) of getting mach to ignore the fact that the Z home switch will be permanently tripped for the rest of the file. This is necessary, as the switch remains depressed by the pushing action of the Z axis during printing. I achieve this manually at the moment, and I could ( I suppose) send the switches signal through external logic that tells it to do the same thing automatically, but is there a way mach could do this on it's own?

125
General Mach Discussion / Re: Gcode to zero Z axis during run
« on: April 13, 2014, 05:01:52 PM »
I think that's clear, G31 sounds like it does what I need done. I'll re read this again tomorrow, along with relevant bits of the manual, and make sure I know what to expect before I run this. Thanks again.

126
General Mach Discussion / Re: Gcode to zero Z axis during run
« on: April 13, 2014, 04:31:08 PM »
Thanks BR549.

My code should withdraw the Z (plunger driver) fully at the end of the previous file, and set Z to zero there, so I don't need to withdraw at this stage in the code.

Can I just use the second line on its own to achieve the zeroing? Or use my original exaggerated move , as below? And yes, Z homes towards the plunger.

G28.1 Z40000    'ensures pressure switch wired as Z home trips regardless of length of plunger
G92 Z0.000       'sets Z to zero from its current value

127
General Mach Discussion / Re: Gcode to zero Z axis during run
« on: April 13, 2014, 03:46:07 PM »
My setup isnt a milling machine, its a plotter. Part of its operation is an extruder pump driven by the Z drive. It picks up a syringe of paint, (which may have a plunger height of 1/4 inch to 3 inches), it then advances the Z drive until it trips the pressure switch (wired as a limit switch currently) that tells it to stop advancing because it's made contact with the back of the plunger. As all plungers are a different height, I need to zero Z 'on the fly' so to speak, as the main code always starts from Z0. At the moment, I just zero it myself at the keyboard, but it needs to happen without my intervention.

So I'm not really sure what offsets are in this context;- I kind of thought that was what I was doing. I may be wrong, probably am...

128
General Mach Discussion / Gcode to zero Z axis during run
« on: April 13, 2014, 02:11:26 PM »
I may be over complicating this; I think what I want to do is to zero my Z axis in code...

I have code that moves my Z axis until a moveable limit switch is tripped (G00 Z40000; ie a figure so large that it ensures the switch will always be tripped at some point.) When this happens, I want the machine to treat this position as Z0, until the end of the file. All other axes will remain as they are. At the end of the file, the next file will be called and run automatically from within the current file, and so a new Z0 position will need to be found... (at least that's what I intend.)

I looked through a post from 2007 entitled 'Gcode to re-zero Z axis', which appears to be about the same kind of thing.

Poppabear suggested a user defined DRO, which passes a value to a macro:-

'G90 G17
G28.1
M700
(the rest of code here)

Here is the Macro:

'M700.m1s  'metal thickness offset macro

z=GetUserDro(1100)     'get the value of your metal thickness from the dro.
Code "G0 Z" & z        'This moves to the new Z position that you put in the dro.
While IsMoving
WEnd'


I may be misunderstanding what the OP wanted; but I think in order to do what I want, I would need to rewrite as:-

G90 G17
G28.1     'only Z would be enabled for this in my soft limits config?
M700
(the rest of code here)

'M700.m1s

z = GetUserDro(1100) 'get value from my DRO
Code "G52 Z" & z
WhileIsMoving
WEnd

Am I right in thinking that this would move my Z axis until the switch trips, then Z stops moving, and mach sets the current Z position as Z0?
Or is there a function in mach that does that anyway? Can't test this for a few days now, which bugs me.

129
General Mach Discussion / Re: 'run from here' not working as expected
« on: March 06, 2014, 02:05:46 PM »
Thanks, I'll definitely have to buy a licence at some point; I'm also waiting to find out what Mach 4 can do first...

130
General Mach Discussion / Re: 'run from here' not working as expected
« on: March 06, 2014, 08:33:03 AM »
Oh that's a shame. I'll go back to doing it the long clumsy way until I know for sure my machine is viable. At least I know it wasn't anything I was doing, its behaviour was totally baffling...

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