Another Lead Screw Nut Stripped Out

[Esquare]

Support offer to send me another lead screw kit this time but I declined as I did not feel it necessary at this point.

[BallerinaCats]

What do you mean by not properly locking down the bed? I read the Wiki and it says to use the four locking screws, is there some other trick I need to be aware of?

[Esquare]

No, just make sure the bed is completely bottomed out all the way around and then put the screws in. I think at least 1 of my screw points female threads are stripped out.

[KidDoc1992]

I do feel that I have locked the bed down as instructed, each time, but for whatever reason it continues to happen.

The a a for the issue to be escalated, I received a response a few days later basically saying that they would not be able to replace my machine. They did say they would provide another set of screws and nuts to replace the ones that were damaged.

I also tried pointing out the multiple users on the Bambu site that have had this issue. That did not seem to make an impression.

I did replace the defective nut again and for the last two weeks, the printer has been working without any issues.

My H2C now has 1200 hours on it, and so far I’ve had no issues.

[webbfire]

I have not yet had an issue with the screws stripping but have noticed that maintaining the rear screw in my H2D is a real pain. Why would they not have a removeable panel in the back for better access? I can only imagine what the process is like to replace one of these, how much of the printer do you need to disassemble when you replace the screw?

[krellboy]

@KidDoc1992

The a a for the issue to be escalated, I received a response a few days later basically saying that they would not be able to replace my machine.

Are you out of warranty?

[Esquare]

I don’t believe so

25 characters

[Esquare]

I’ve gotten pretty good at it by now but it does entail quite a bit of disassembly. MiamiJerry has a modification that he came up with to make it easier but I haven’t done the mod yet.

[KidDoc1992]

Yes, for replacement. But I asked for replacement after the second occurrence, and I was still in the replacement window. But, I was refused.

Still receiving replacement parts free of charge.

[KidDoc1992]

I saw that. May be worth doing if this continues.

For better or worse, at least I don’t have to look at the instructions step by step and read it three times anymore!!!

[webbfire]

Thank you for that tip! When the time comes I am sure it will come in handy!

[BallerinaCats]

I am not excited about the disassembly - well, more so a little nervous about the reassembly part. Generally the 3D printing is “my thing” and my husband does not get involved, but I have already given him a heads up I am going to need some muscle to flip that baby over and contribute some extra hands where needed. He agreed before he saw the Wiki.

[Esquare]

I found the wiki to be decent and helpful. As long as you familiarize yourself with it before hand you shouldn’t have any problem other than muscling the printer around. Just take your time and be patient

[BallerinaCats]

Yes, I do have to give credit to Bambu for the Wikis. Thank you, and I will!

[max225719]

I have been through multiple replacement lead screw kits on several H2D’s in my farm. ALL OF THEM are again failing. This is 100% a wear item. If you completely clean the leadscrews and regrease and then run a 2 day print the leadscrews will be covered in black grease. The grease is black due to the brass wearing down and the particles contaminating the grease.

BambuLabs have told me to ONLY use THEIR grease. No Superlube greases are acceptable despite there recommended list.

Now I have used a 3D printed nut in the rear axis during my first nut failure. It was printed in PLA-GF as a whatever who cares as long as it works till a replacement arrives mindset. It has OVER 2,000 farm hours running 24/7 and the grease stays clean, there is ZERO physical play in the rear Znut. It is not wearing at all and the leadscrew its self is showing no abrasion from the GF filament. It is the ONLY Z nut in all of my printers that is play free.

I am currently desperately trying to save several H2D Z nuts by cleaning and regreasing every print (24-48 hours) They have significant 2-3mm of play at the moment and are bleeding brass like crazy. I will no longer be dealing with Bambu’s support as the printer will be out of warranty soon and instead replacing all Znuts with printed ones.

[hotellonely]

@Elmos_prints

I have almost 2000 hours on the H2S and H2C and almost 4000 hours on the H2D. No problems yet but there is some ‘play’ in the rear nut when I lift up the bed by hand. Until now print quality is not affected.

It’s normal to be able to lift the bed bearings up, that’s backlash which is unavoidable and also crucial for reducing the wearing.
It’s only really wearing when you can push it down.

[hotellonely]

@Demianiv

I’d like to share some technical observations regarding my Bambu Lab H2S after 500 hours of operation.

The XY Motor & Belt Issue:

Simultaneously with the Z-axis noise, a “cracking” or “clicking” sound appeared in the XY motor area. Initially, I thought it was a pulley or the belt (as I noticed the belt was being worn down/shaved slightly). However, I confirmed it was the motor: every “click” corresponds perfectly with visible gaps or artifacts on the printed parts. It seems like the motor is failing internally and losing steps.

Yes, your XY motor is probably cooked.

Z-axis Backlash & Structural Tension:

Most of my prints are small engineering parts (~30mm height), so the wear is heavily localized. I noticed a knocking sound at 200h, and now at 500h, the backlash is significant.

• Leverage Effect: Interestingly, the bed play is much more noticeable when the platform is at the top of the screws compared to the bottom.

• Radial Wobble: The lead screws have clear side-to-side wobble inside the nuts, indicating the internal threads are likely “chewed” out.

• The Tension Experiment: My right lead screw was visibly tilting when the bed was at the bottom. I loosened the three bed mounting brackets (plastic slider connectors), and the tension was released immediately — the screw returned to a perfectly vertical position. This proves the bed was factory-installed with an offset, creating constant lateral stress.

The Maintenance Paradox (4-start vs 3-hole):

There is zero official guidance on replacing these nuts, which is a problem because:

• The lead screws have 4-start threads (90° phasing).

• The nuts are fixed with 3 mounting holes (120° spacing).

• This makes it a “positioning puzzle” to find the correct entry point so all three Z-nuts are synced without internal tension. We really need a professional service guide for the H2 series.

Current Status:

I’m still printing with the backlash and the clicking motor for now. Bambulab Support has approved a warranty replacement for the XY motor and the Z-axis assembly. I’m sharing this to highlight that Z-issues might be caused by assembly-induced tension, not just lack of lubrication.

Yes, if installed incorrectly, the leadscrew might cause a significant amount of extra wear on the bearings.

Good luck on your repair and let us know the results

[krellboy]

@Demianiv

We really need a professional service guide for the H2 series.

I’ve seen people asking for fastener torque specs, that would be my main complaint right now.

[wizardofish]

Jesus that’s a horrible situation especially in a farm. If they came out with a more durable kit I would buy it. Hope they don’t quietly leave it alone until H2Ds become ‘legacy’ machines and no longer supported…

[max225719]

I’m preying a 3rd party company comes by and makes us better nuts. Anything’s better then these. You can tell by the machining on the new nuts that these were penny items and made as cheaply as possible.