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8801

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 19, 2008, 01:55:50 AM »

Just a 'by the way' thing but if we profile cut a shape the number of +X steps equals the number of -X steps and the number of +Y steps equals the number of -Y steps (this applies to any object where the toolpath starts and finishes in the same place). If steps are,say, gained at random then a 'gained step' when traveling in the +X direction automatically becomes a 'lost step' when traveling in the -X direction (and the same will apply to the Y axis) then gained steps may well cancel each other out exactly and no error will be observed. The same argument will not apply to lost steps, which are created somewhat differently.
All though it is a (very) long shot it is possible this could be cause of your problems.

8802

SmoothStepper USB / Re: Got Smoothstepper 1.2

« on: August 16, 2008, 08:20:42 AM »

Good point Hood !

btw. If Mario keeps that up he could go blind.

8803

SmoothStepper USB / Re: Got Smoothstepper 1.2

« on: August 16, 2008, 05:09:16 AM »

1) The existing Mach setup should work OK 'as is' for the initial tests.

2) As the manual says:-
3 Resistors, used for termination at the differential receivers. These resistors are provided for your
convenience if you choose to terminate a differential encoder. The resistors may be attached to
the wires on the screw terminals. They may also be soldered to the circuit board if you are
qualified to do so. The resistors have a value of 121 ohms. This may or may not match the
impedance of your cable. That is one reason they are not pre-installed.

If you are not installing encoders just forget about the resistors.

3) If it has USB then it should work just fine with your notebook.

8804

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 14, 2008, 10:28:37 AM »

Hi Carl,

I have been following this thread with interest, as have many others, and I would like to add my comments regarding progressive errors.

1) Errors are caused by 'gained' or 'lost' steps.
2) Lost steps are usually caused by the stepper's inability to drive the load presented (speed, torque,friction etc.).
3) Gained steps are usually caused by noise spikes occurring on the 0 Volt side of the step pulse train from Mach on the LPT connection.

If you are going to replace your breakout board then try using 74LS14 schmitt's in series with the step inputs (direction inputs will be ok straight through). One schmitt is ok if you change the config, ports & pins, motor outputs, to 'step low active uncheked' else two schmitt's in series (like beer they come in 6 packs).

Good luck.

8805