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Topics - Lemic

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1
General Mach Discussion / Noise Issues causing all sorts of problems
« on: June 10, 2011, 11:08:54 AM »
I am having what I guess to be noise or interference problems.

Most common is a random "external e stop requested"

however I also get a random resetting of my Z position. That is to say I will home the machine, then as I run the program it (Z readout on the DRO) will suddenly change, and not once has it changed so it didn't drive a tool down into my work.

it has twice changed in the middle of a program while it is running.

Just last night I was trying to carve an intricate logo on to a polished aluminum billet 12x 18 x1. I used the probe to touch off the surface and set my Z .100" higher than the surface and ran an "air cut"

The program ran well was centered. I rewound the program, sent the head to Z 0.000, entered .100 on the DRO, homed the machine  and when I started the run it dove full speed into the face of the aluminum with enough force to spear the bit into the billet and shear the mill head off the mount. After I cut power to the mill head and hit the feed stop, the Z DRO read at -4.6293,

I built my controller from a smooth stepper and Gecko G540.

my limits are optical and I have a 1uf electrolytic already between the ground and supply feeding the limits.

I've set my debounce to 20,000! and I still get the external estop request.

I've completely eliminated my Estop circuit and wired a jumper between my 48V power supply(-Vdc) and pin 10 of the G540.

the 3 internal power supplies have all the negative terminals daisy chained and sent to ground, the earth ground is no where near the chassis ground.

as far as I can tell I have no ground loops ,I build guitars and amplifiers and I am very familiar with ground loops.

I've COMPLETELY removed all 120 VAC wiring from the controller box (mill head and router head power) and re routed them to drop down off the ceiling and at 90degrees to the controller and the wire routing.

the circuit that the controller is powered off of is on its own breaker and has a separate ground rod 12' away from the shops ground rod. The computer, monitor and external hard drive are powered off this too as not to cause a ground loop.

I'm down to two other possible sources:

There is a large 6 bulb fluorescent light fixture maybe 4 feet from the controller .

Maybe the shop power has interference? the power lines  run under high tension lines about a mile up the road. I'm VERY rural and am the last house on this grid with the the last pole sitting in front of the driveway and the power lines terminate on it.

I am at my witts end here.


Ray






2
Tangent Corner / what kind of liner motion ways are these?
« on: April 21, 2011, 12:54:59 AM »
This is the  LM ways on my machine.

Id really like to be able to know what type they are.

They are mfr'd by THK, but I have poured over their site and could find no reference.

Thanks
Ray

3
General Mach Discussion / home and limit setup questions
« on: April 18, 2011, 04:56:43 PM »
Total noob, so bear with me please.

I'm making progress landing everything, motors and limits and such,

I'm running Mach 3 into a smooth stepper and then into a Gecko G540.

when I go to home  the machine it goes past the Z--/home limit till the Z axis binds.

If I jog the Z it reads and stops.

If I hit the Estop, and then reset it the Z it will act as if the Z home switch was made and continue to do the home routine, with the X axis moving to the limit then backing off then the Y axis does the same.

Also, If I jog into a limit switch, I have to shut the machine off and move the axis by rotating the ballscrew with a pair of pliers until it is off the limit before I can reset it, is there a way around that?


4
Hi,
I'm new to all this stuff, CNC, Mach 3, everthing.
I acquired someones project that was setup with Mach3 and drove servos. after finding out servos were not the best fit for my application, I bought stepper motors, a G540, Smooth stepper, and a 48V power supply to retrofit in the machine.

So now I've installed the motors, made cables, (controllers are just mounted to a board till I make a suitable cabinet to house it all), figured out how to make the optical limits work and now I don't know where to land the signals from the limits.

The optical limits are NPN and go from an active low of about a half volt to an active high of 5V when the flag breaks the light beam.

I've attached a sketch of my wiring so far.

Besides not knowing where to land the signal wires from the limits, I have a few other issues.

when starting up Mach, I get a message estop not assigned to smooth stepper. I click the window and click reset on the screen and the message appears again, then I click it again and it goes away. If I hit the Estop, the red fault light goes on  on the G540, but Mach doesn't show that an Estop is active.

The other thing is when I move the X axis .500 inches (according to the screen on Mach) I have only 0.3965 movement of the axis (as read by my test indicator)

any help will be greatly appreciated.

Ray

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