Z axis problem

Hi everyone.
I am new to the whole 3D printer thing

I bought a laser-cut Mendel and assembled it, then I made sure
everything moved smoothly before I connected the belts.

Now that the belts are attached, X and Y axes are fine, but Z
barely moves. It makes noise and doesn't move.

When I need it to move, I pull the belt in the right direction and it kind of moves
a bit and then stalls again.

One thing I noticed is that X and Y (when powered) cannot be moved by hand
(as expected with stepper motors), but Z axis moves as if there is no power
applied to the motor.

One other thing I tried is I disconnected the Z axis stepper motor from the driver
board and shorted the green and black together, then pulled the belt; as expected,
I could feel the change in tension as the shaft turned. Same thing with shorting
red with blue, so it is not the motor.

I suspect the driver board. Can someone suggest anything else?

I'll be at the shop again tomorrow and will try another driver.

I need to note that the gears that are on the motors were also laser cut from plywood.
I think it was stupid, but that's all I got for now. The problem with these gears is that
the laser must have been "not perfectly vertical" when the pieces were cut so the teeth
are at an angle compared to the shaft. This moves the belt in one direction or another,
depending on the direction of rotation.

For now, I superglued big washers to the gears so they retain the belt.
Once I get it going, I'll make new gears out of plastic and glue them on the shaft, but
I need the whole thing to get going first.

Please help.

Thanks.

- Nurchi

In the beginning I had a similar problem with the Z not moving. For me it was as simple as the x-axis not being the same width as my Z-bars (duh I said) But it might be something that is overlooked. Also maybe not enough current to the motors? Do they turn without a load to them.

---

Ryan
Quality Engineer & Hobbyist
thingsandtrains.blogspot.com

Not enough current is what I suspected too.

The drivers have a potentiometer that adjusts PWM to the motors.
I played with that too. The only thing that changes is the noise the motor makes

I'll try another driver today and see if it changes anything.

Thanks.

Here is what I just noticed:

When the machine is powered up, the Z-axis motor is not move-able (as expected).

As soon as I connect the USB (before even starting any software), it gets loose as
if the controller is "told" to release power from the motor.

Firmware to blame?

I forgot to mention that I was using Pronterface

When I dropped the speed of z-axis from the default 200 to 20, it all just worked.

I'll experiment with other numbers, but got it working.

Thanks.

Hi nurchi!

My z axis had a similar problem before I got good prints working which arose from mismatched microstep settings. I burnt out one of my motor drivers in seconds because I had my hardware set up to accept no microstepping, while my software was sending out 16x microstepping (essentially giving my motors 16 times as many steps, 16 times faster than it was supposed to receive them). Does your axis jump and lurch around instead of a slow gentle movement? If so you may want to check your microstep settings.