Y axis not aligned

Veröffentlicht von: @sammyjohn

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Hi everyone, 

I am newbie to the world of CNC. So hopefully my questions are not too painful for those professionals. But I would love some help. I am having a lot of trouble assembling my D3 840 machine. There have been countless issues along the way, but the most recent that I cannot seem to work around is aligning the Y axis. The left side (if I am facing the motors) is a few mm ahead of the right side. And no matter how much I tighten or loosen the screws I have not been able to figure it out. Sometimes the right side hits the backplate as well, even though I can activate the limit switch by hand and most of the time it works when homing. Probably need to switch those little red cables at some point as they were slightly squished, but still seem to work when triggered. The main problem right now is alignment, can anyone suggest a way that I can align my Y axis so that I can begin to use the machine?

- Grow A Garden -

Move the gantry slowly to one end, then the other, observing if it hits the switches at the same relative position.

Measure the distance from a fixed reference point on the machine to the gantry on both sides when at the same travel point. Adjust the position of the rails or the limit switch triggers accordingly.

Hi SammyJohn,

Welcome to CNC — we’ve all been there starting out 🙂

From what you’re describing, it sounds like your Y-axis gantry is out of sync (very common during assembly). A few things you can try:

1. Manually square the gantry – Power off the machine and gently push both sides of the Y-axis so they align evenly with the front frame.
2. Check belt tension (if belt-driven) – Uneven tension can cause one side to move ahead.
3. Dual motor sync issue – If your machine uses two Y motors, they might not be perfectly synchronized. Try unplugging one side, align both sides manually, then re-home.
4. Loosen and re-tighten frame screws – Slight frame misalignment can cause this. Loosen the frame a bit, square everything, then tighten again gradually.
5. Limit switch consistency – Since you mentioned the right side hitting the backplate, double-check switch positioning and wiring.

Also, I recently came across a guide explaining alignment basics and troubleshooting mechanical sync issues — it might give you a clearer idea:
https://nolcardcheckbalance.com/

Hope this helps — once aligned, your machine should run much smoother