Calibrateing/Homing & Z Knobs

Ok, I am inching closer to getting this thing completed. I was able to get movement last night, but now I have some questions.

I can’t seem to find complete instructions on how to use the LCD to set the cutting area for the machine. Can someone either explain this or point me to the repository for these steps?

Also, does anyone know where I can find STL files for Z axis knobs? I thought I saw some on Thingiverse but now I can’t seem to locate them.

You don’t. You make your Gcode and ensure it isn’t too big for your build. Softstops would hinder use, or be a non dependable crutch. Meaning the machine size is only if you start at zero.


That went away with the 525 update and T8 leadscrew. You should very easily be able to turn the coupler by hand.

Ok, so I seem to have gotten most everything sorted out except the Z axis. I am having a problem getting the motors to respond correctly. Both motors will turn clockwise with a clockwise turn of the LCD knob, then when I turn the LCD knob counterclockwise one responds correctly and the other turns in the opposite direction.


Do I need these motors connected to the same cable or does one need to be plugged into one of the Z ports on the Rambo and the other into the other?


To be clear on the homing and calibration. Just pick a ‘home point’ and make sure the file fits within the mechanical limitations of the frame and then run it. The virtual dimensions are contained within the cut file and not within the set up of the controller. Is that right?

They are pretty stiff and one seems to bind at the bottom. How do I ensure the Z axis pipes are square? I assume if they are not that it would cause binding. The top mounts keep them square at the top, but what abotu the bottom?

Plug it in a run it directly with repetier host. What you are saying here should not be possible. You are connected with my series wiring kit? Up is up and down does what?

series wiring cable, included with my bundle. Is that what you bought, or are you doing this yourself?


Again, if you bought it all from me, calibration should not be an issue.


Unclear. What are you trying to do and how are you trying to do it, exactly. Virtual dimensions? If you want to cut 1’ x 1’ that is as far as it will go, so you make sure you have room for your cut. I am unclear on the concern here.

I laid out my steps in the instructions, I start my cuts at the surface of the material bottom left corner. So I get the machine there and hit go. The gcode includes the zeroing command, all in the instructions on the assembly page.

Yes, I bought it all from you. One would think up was up and down was down, but that is not what I am seeing. I have a funeral this afternoon, but I will record a video when I get back and show you what it does. Everything works well except the Z axis.

If you were running the Endstops firmware and one of the Z endstops was triggered that one would make one of the Z motors not change direction. This is solely based on the thought of running the Endstop firmware which all motors would run on their own drivers. Not knowing the setup its just a thought.



Here is the problem I mentioned earlier. No matter which direction I turn the control knob the motor turns one direction.


I am not running end stops.

Your Z axis is binding. (I think)


A few things to look at.

-The Z rails can touch ( and should) but not stick. so if you a cocked just a bit they will grab and bind. This is just a friction thing. For safety do your tests at the stop block so you know the machine is “straight”.

-Both sides. I would start all test (and cuts) from zero. Meaning both XZ mains should be resting on the rollers. Kinda the same as above, you get it crooked and it will bind (and break parts). So always, no matter what start from Zero so both sides are level, then move up and down. Most LowRider’s will not stay in the air unless they are binding. That is actually how it got its name, power it off and it looked like the hydraulics on a lowrider lowering the car. Original name was “full Sheeter” or something like that.

-Where I actually see a bigger issue. What is up with your coupler? That things should be straight and smooth, Is the leadscrew straight and super easy to move by hand up and down on both sides?

What I am seeing is it is moving one direction, down, but binding the other and slipping, down. I have some videos of the previous version with a bunch of weights on each side, the steppers have no issue moving, unless the nut/screw combo in binding. Make sure it is free and smooth, lubed and it should be fine.

P.S. How your video started out…“okay Ryan” I winced, thought my Dad was about to yell at me for using his tools improperly, AHAHAHAHAHAHA.

“Is that a screw driver or a chisel in your hand?”…“screwdriver”…“then why the hell are you waking it with a hammer? Go buy your own tools” Then I would catch him doing the same thing all the time…punk.

I sent you an email. I will address the coupler problem, but the bigger problem is one of the stepper motors is defective. I isolated the problem and replaced that motor with another known good one. It is definitely failing.

I wonder if one of those coils isn’t connected. Either a bad wire or a bad motor.

The steppers move by energizing one coil, and then the next. If one coil doesn’t work, then the motor can seem to bridge the gap when going down, but it sounds like it skips when going up. When the bad coil is supposed to be energized, it drops farther than two full steps before the good coil gets energy.

If you have a meter, you can disconnect that motor and measure the resistance across each coil. They should be about the same (somewhere around 6 Ohms). If the motor has a problem, one of them will be huge. You can also try closer to your control board to see if it’s the wires.

If you don’t have a meter, you’re stuck looking at things very carefully and maybe swapping the motor with another one. At least you have one good Z, so it would have to be after the split.

I could be wrong, maybe it’s binding.

Ah, I didn’t read this before my post.

Yep, that is the culprit. You pretty much nailed it. I should have isolated the problem and then started eliminating possibilities 2 days ago, but I was like “it’s a new motor. It HAS to be good. Must be something else.” Nope, it was the simple thing from the beginning.

Can you try flipping the plug over and see if it goes the other way. As Hefe pointed out have a close look at the connector to make sure they are all seated. Maybe even pop them out of the plastic plug to look for a poorly connected pin. I have no problem replacing it but it could be something super simple. When not attached to anything does it go both ways, as in no load? I ask because unless there is some foreign object inside the stepper it doesn’t know which way it is going, if it can go one way it should be able to go the other way. The magnets just get energized the other orientation instead of 1-2-3-4 they are energized 4-3-2-1.

Out of all of these steppers there has only ever been two that I can think of one had a bent shaft ( I have no idea how that happens) the other seems as if it was dropped and 3 of the wires where almost pinched off at the corner of the stepper where it must have landed on them. Hopefully you see a single loose wire and can fix it so you can be running today. If there is an unsolvable issue I have no problem replacing it, that would make 3 out of thousands.

I am pulling both Z motors today to get the couplers in line. I will hook them up outside the frame and see how they perform. I will report back when I have more info.

You’ll know better than me on the couplers (I’m only looking at the YT video), but they look like they are just stretched out, and maybe they are in line? I definitely agree that they need to be very close to aligned or they will bind.


So I took both Z steppers off and wired them up and low and behold… yep, both work great! Ryan, sorry to tell you, there is no 3 out of 1000s. At least not this time.

It looks like alignment and binding is what was causing the problem. I am not sure how to correct the alignment issues so I am defaulting to the wisdom of the forum. Here is the video of what I am facing.

Sweet, means we can adjust the problem out!

It almost looks like your Z rails are crooked. With the leadscrew out of the way will that axis sit flat on the rollers?

So maybe check the gap on the 4 screws on the XZ pieces and make sure they are all equal, 2-3mm if I remember correctly. They also don’t need to be super tight.