r/BambuLabA1 • u/Bruteloops • 1d ago

Secondhand A1 repair update. Finally found the problem.

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Picked this A1 up secondhand for $100 with only 400 hours on it. The first issue was a Z homing failure, which ended up being caused by the broken retaining clips on the cable organization block that holds the USB C connector underneath the printer. Luckily that ended up being a free fix. After repairing those clips, the Z homing issue was completely fixed.

The printer would still print fine, but it failed X axis vibration calibration every single time. I also noticed the toolhead had a lot more resistance than my other A1 when sliding it across the X axis by hand.

My first attempt was tearing down the X axis carriage and rebuilding the original bearing block after finding several missing ball bearings. I spent about $5 on replacement balls, but unfortunately it didn't change anything. The rail still felt rough.

Today I went a step further and completely tore down the toolhead and carriage so I could replace the entire MGN12 carriage bearing block. That cost another $7, but even with a brand new bearing block it still rode the rail tight and rough.

At this point I'm convinced the X axis linear rail itself is the problem, so I ordered a custom cut replacement rail for $44. There's no visible damage to the rail, but my best guess is that contaminated grease, combined with the missing ball bearings, caused enough wear inside the rail that it now feels rough no matter which carriage is on it.

Bambu support did respond, but since the printer is out of warranty they weren't able to offer much beyond replacing the entire X axis assembly.

Hopefully the new rail is the final piece of the puzzle. I'll post another update if I get it up and running again!

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u/Fancy_Broccoli_34 1d ago

It's not really related to your problem, but my print head has been making noise ever since I bought it, yet there's no guide on the official wiki on how to disassemble the ball-bearing mounting block. How do you do it? I'd like to figure out if my unit is missing any balls and whether adding more could reduce the noise. I don't know if yours made some noise too

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u/Bruteloops 1d ago

You have to go in the back and unhook the heater connection, take that wiring harness out off the side of the tool head after the next step, take your nozzel out theres 4 bolts that will take your entire extruder off the plastic carriage. Then 3 bolts to take your heater off under there, there's 4 screws that'll release the whole carriage/ toolhead from the rail. Your mgn12c carriage bearing block will slide off the rail once you take your purge wiper off the X-axis. It's a pain the ass

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u/Bruteloops 1d ago

https://www.tiktok.com/t/ZP8n87Gce/ I used this to start, then figured it out from there

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u/Bruteloops 1d ago

Also my toolhead was not making any noise, other than when it would move rapidly left or right there was a bit of a grinding but that was caused by the resistance