[Cartierusm]

I've read a lot here and in Mach3 tutorials it says "do this and tune that" "unless you are loosing steps". How do you know if you are loosing steps? Is it a mechanical thing where you start from 0,0,0 cut a part go back to 0,0,0 and see if it's off or is there something in the program that will tell you? BTW I'm using stepper motors.

[stevespo]

Without an encoder on the stepper, the software has no way of knowing if you've lost any steps. I use a dial indicator mounted to the frame, and check periodically by doing a return back to 0,0. There are probably other ways as well.

Steve

[test driver]

I found I was loosing lots of steps at one stage (I could actually here when it would miss them). After I upgraded my computer, I haven't lost a step yet and I am able to rapid transverse at a higher speed without any problems.

[probinson]

You want to run each or your axis at maximum rate with a nominal resistance then bring them back at a slower rate with no resistance and repeat this a few times then do the reverse, step out slow and back fast in case you have binding in only one direction.

The zero position should not change. If it does then you have a problem with missing steps.

[wjfiles]

I start most of my machining moving away from the home.
The zero all axis at the new start position. Then I press the machine co ordinate button and note the positions.
Between operations I Go to Zero and then check the machine co ordinates and missed steps will show up.
For some reason I lose steps running slow, but not when I run at normal speeds.
It would be nice if there was a way to incorporate encoders on steppers ???.

wjf

[probinson]

wjfiles,

Sounds like your problem is low torque from your steppers. When the travel is slow, the stepper needs enough power to get the carriage moving from a stop for each step but as travel speeds increase the carriage is already in motion much of the time and doesn't resist the step as much reducing the chance of a missed step.

There is also the condition where the drive to the stepper is too high and they move so fast they can over shoot and make a double step. This can also be a cause for what seems like missed steps that show up more at low speeds.

[DrStein99]

It would be nice if there was a way to incorporate encoders on steppers ???.

wjf

Yes it certainly would. Mach-3 has DRO's for external encoders. To my knowledge there is no way to close the loop other then to write a custom operation in the SDK. I cant believe after all this time has passed and closed loop is still not available.

[Mr.Chips]

Between operations I Go to Zero and then check the machine co ordinates and missed steps will show up.
wjf

I think I may be confused, but hey I confuse easily.

You say you go to Zero. That would be electrical 0,0 on the X and Y axis correct?

Even if you loose steps the machine would still go back to (electrical) 0,0 when you told it too.

However this would not be the physical 0,0 in reference to the table, it would come up short on the axis that lost the steps.

Please help me understand this.

Hager

[Cartierusm]

Here's an easy way. I hook up a laser centerfinder to my router. Mark a piece of tape with a thin line cross hair. Place it below the router exactly under the laser point until it's perfect. Then zero out the DROs, cut something using the Mach3 wizards, jog around the table, whatever, just move the gantry. Then hit goto z and it should line up on the cross hairs. But this may actually be more for table accuracy and not if you are losing steps.

[Coogrrr]

Remember you cannot get the encoder DRO's in mach to show accurate information unless there are pulses sent to an input on your lpt port. This will be read on the correct pin and the inbound pulse/steps are shown on the encoder DRO so no looping it.

Now a suggested solution? grab an old mouse, you know one that had a ball, not a new fangled ball-less mouse! :rainfro: maybe grab 2 or 3. Inside these are little encoders to tell the computer when the x or y axis was moved when you moved the mouse so that the cursor on screen would move accordingly.

I plan to adapt this onto my machine maybe on the stepper axis shaft somehow....


just my 2 input pulses worth!

Coog

[High Seas]

I'll try and understand the question you've asked...

says "do this and tune that" "unless you are loosing steps". How do you know if you are loosing steps? Is it a mechanical thing ...

Yes/No/Maybe? Mechanical in How you might see the lost steps.
Without encoders for positive feedback to the control software there is little way for MACH to tell/show you lost steps.

1. Assume the machine is square and not binding, that the motors are working, and all setups are correct.
2. Draw a square - 4 equal length sides in your fav design program.
3. Have a constant cut depth, then
4. convert it to a milling(CAM) program.
5. Run it on your machine. No simulation here - make chips and dust! (Try blue foam to minimize load on your tooling.)

6. Review your Results:
If the square you actually cut -- isn't and the depth changes - you can begin searching each axis for the problem.

Also you might see that the tool doesn't return exactly to the start point (if you told it to go there. Do that after running the cut)!

Hope that helps -
:cheers: Jim