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X axis moves half distance
« on: November 20, 2020, 08:15:12 AM »
I am setting up a small lathe using windows XP professional and Mach3 R3.043.066. mach3 turn.
I have installed a UC100 Controller'

Drivers are set to 800 micro steps/rev
Leadscrews are 1mm pitch

Mach3 settings:-
Xstep pin 2, X dir pin 3
Zstep pin 4, Zdir pin 5
Motor Tuning in Mach3 800 steps/mm
Velocity 800
Acceleration 50
Step pulse 5 us
Dir pulse 5us

Using the parallel port:-
X and Z dro set to 0
Using MDI - G1 X1 F20 X moves 0.5mm
Using MDI - G1 Z1 F20 Z moves 1mm

Using UC100 controller:-
No change

Swopping motors made no change so I reason motors are Ok

Swopping drivers made no change so I reason drivers are Ok

Change Motor Tuning X axis to 1600 steps /rev in Mach3 and axis moves 1mm
Again changing drivers made no change.

Reset to 800 steps/mm

Change X step pin from 2 to 6
Again no change so I reason the BOB is not at fault

Windows reports Mach3 driver and UC100 are working correctly

Kernal speed 25Hz

Change kernel speed to 60Hz Still no change.

So I assume the motors and drivers are OK and the fault lies within Mach3.

Anyone any advice on how to overcome the problem.
Re: X axis moves half distance
« Reply #1 on: November 20, 2020, 12:35:04 PM »
Short Update.

I have put together a test bed  of PSU, drivers motors and BOB. All used on a previous build and working when removed.

I have from the distance past a logic tracer. So I dug it out connected up and here is the result

Probe output is 400pulse/sec TTL (5v)

Probing the step pins for both X and Z axis motors move at a steady rate.

When I connect up the PC I get the same problem i.e. the X motor only moves half the expect amount.

Check the output voltage of the parallel port using oscilloscope and it is only 3.6v so could this be the problem?
Scope shows good square wave with 5us pulse.

Spec for the pc:-
Dell OptiPlex GX620
Operating system Windows XP pro 32 bit.
Port used: Onboard parallel port

I've ordered a PCI parallel port to try.

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Re: X axis moves half distance
« Reply #2 on: November 20, 2020, 12:50:05 PM »
You do realize that a lathe needs to move half the distance in the X axis for the part to be correct, right? You are cutting off both sides of the part in diameter, but the moves are in radius. Sounds correct to me.
Re: X axis moves half distance
« Reply #3 on: November 20, 2020, 03:16:28 PM »
Thanks forgot the turn options in ports and pins. Unchecked Diameter and checked Radius and now working correct.

Thanks again