A1 seems to hit top of Z axis first thing after starting new print

Bambu Lab A1 Series
22

That’s all it would take? Nothing goes in its place?

23

@jaime1269 thanks for chiming in. Since the mini only goes up to 180mm on the Z, I guess something like this would work?

Jaime’s code modified for A1 Mini:

{if (max_layer_z + 100.0) < 180}
G1 Z{max_layer_z + 10} F600
{else}
G1 Z20 F600
{endif}

Secondary option? This will make anything <130mm only go up max_z + 10.

{if (max_layer_z + 50) < 180}
G1 Z{max_layer_z + 10} F600
{else}
G1 Z20 F600
{endif}

I think I will start testing these soon and also think about how to modify the start & end code to work together and prevent crashes.
What’s the worst thing that can happen, the machine rams into an end stop?? /s

24

This is all i have in my end gcode for that line, you are not replacing all the gcode, just the tiny section when it starts to move up.
{if (max_layer_z+50)<180
G1 Z{max_layer_z + 10} F600
I’m pretty sure these printers are using sensorless homing, that’s why there are no physical endstops.

25

Sorry, I was trying to make a bad joke about the machine hitting the top of the Z axis and not trying to infer they have end stops. They are using sensorless homing.

So it looks like your machine will move up 10mm after every print, regardless of print height. I guess this will prevent collisions for all models <150-160mm, which probably covers 99% of all prints I plan on doing.

I may just start with that and see if Bambu support will fix the issue with a firmware update.

1 Like
26

Hello, I also have this problem with my A1 mini. Has anyone successfully solved the problem?
Does changing the printer gcode help? If so, what specific value should I change?

27

I have the same problem but I just manually lower the X axis by “two clicks” .I don’t mind doing that for now. I understood is a known problem and they are working on it so at least I have a workaround.

28

I have the exact same problem here.
The question is, will something break on the Z-axis? If so, does Bambu Lab take responsibility?

29

I started seeing a gap between the gray piece on the top of the Z axis and the Z support bar. I don’t know if it will break, but I frequently print tall objects and I don’t want it slamming up 1,000 times to figure out.

Sorry it’s been a while, but I have been using modified start/end G code since my previous posts and I do not have any more collisions.
Let me remember what I did before posting the code.

30

So I just went with a very simple approach to avoid the collisions on models <145mm tall in hopes that Bambu will release a new start/end code sequence soon.

For my purposes, I only modified the Machine End G-Code section from:

{if (max_layer_z + 100.0) < 180}
G1 Z{max_layer_z + 100.0} F600
G1 Z{max_layer_z +98.0}
{else}
G1 Z180 F600
G1 Z180
{endif}

to:

G1 Z{max_layer_z + 5} F600

This simply raises the nozzle 5mm after the print is finished and leaves room for the movement in the Start Code of the next print.
Again, I believe this should avoid collisions on all models <145mm but be sure you know what you’re changing & test with caution.

If you want to print taller objects >145mm, the start G code will have to be modified to reduce the +Z motion. I can post where I think that should be changed if anyone wants.

3 Likes
31

I got my A1 in the last few days and already had to witness this behavior.

Now that you sent the modified G-code, I’m hoping to fix this issue. But honestly, I’m a noob when it comes to G-code. I looked into the original G-code and tried to adapt what you were writing, but I’m not able to. Could you provide the complete code so I can just copy and paste? Or your profile?

Sorry for the dumb questions, but I’m really not able to.

Thanks for the help!

1 Like
32

Do you also have the code for the start if I want to print higher objects? I’m glad for any help.

33

I just experienced this for the first time on my 2-week old A1. It sounds really really terrible! I hope Bambu Lab will fix this soon.

34

problem solved with this gcode

35

V4 2024-07-15

1- fix z axis hit the top , now when you start a print z go down first -90 then up +90

you must have 90mm of clearance under the nozzle otherwise the nozzle will hit the bed

2- lower the z-motor current in case off in case of collision

because when you home the printer it will go up 90mm by default and cannot be changed with gcode

even if you’re nozzle at maximum height it will be fine

36

I have the same problem too, sounds like the machine is going to tear itself apart. Happens with tall prints, we’ve had new firmware recently but it’s still not fixed months alter.

1 Like
37

Same problem here on my A1 with a 165mm high print. Shocking noise when the printer bangs to the top at the beginning of the print.

38

This problem is still there in 2025. Does BambuLab acknowledges this?

1 Like
39

Just had this happen on my A1, when starting a new print after a tall print the machine hits the top of Z axis and make a terrible noise.
I would have expected an official fix from Bambu to this considering for how long it have been reported.

1 Like
40

Same issue here. Hits to TOP like crazy.

41

Yes, I too am like everyone here having the same issue. I was freaking out when it happened seeing how this is my first 3D printer and it is an investment for me and hopefully it has not damaged anything in the printer. I read here that someone called Bambu Lab and they said they’re aware of the problem to just manually hold down the button to move the z-axis until a firmware update had been issued. Hopefully sooner than later.