Swapping an LPU

:ballot_box_with_check: Step 1: Establish cleanroom

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Wow that’s intense!!! :grin:

which Form#? after how many print hours and how much did it cost?

also: let’s toast for a great new year, guys!

Form 3. It had some problems out of the factory, they sent a new LPU under warranty.

Happy New Year!

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Does anyone know this information actually? the LPU is not listed in the web store but is touted as user-serviceable
I haven’t find an expected lifetime and cost.

So you’re not supposed to remove the whole cast aluminium assembly? But actually have to open it?

That picture was a bit tongue-in-cheek; we have a dog and I wanted to minimize errant strands of fur or other contaminants.

Here are a few snaps I took before packaging the old LPU up to send back. That whole unit is what gets removed.

Andrew “bunnie” Huang has a great Form 3 teardown where he delves right into the heart of the LPU, but he got it out the hard way (you don’t need to do nearly as much disassembly as he did; it’s just three hex bolts, a thumbscrew and some wires).

Formlabs has great documentation and photos covering how to swap it out. It’s not terribly difficult, although it would be a lot easier if they’d combined all the plugs into a single cable harness instead of three (plus the ribbon cable). Support probably only shares the document if they’re shipping you a replacement, after walking you through other troubleshooting steps. They send you everything you need (including tools, PEC-PAD’s and a spare ribbon cable in case you damage it during the procedure).

No idea on lifetime. Until they’re in the field for a few years I would guess Formlabs doesn’t even know for sure. Inside the LPU is a laser, single galvo, parabolic mirror and supporting circuitry. If I had to speculate I’d venture it will get similar lifetime as the Form 2 laser / galvos. Anecdotally it does seem well-made. The metal parts feel solid. The replacement shipped padded with the thickest foam I’ve ever seen for a consumer product (averaging around 7cm of cushion on all sides).

My only disappointment was finding a small, plastic Delta fan. It’s part of the printer, but is positioned on the carrier, directly adjacent to LPU heatsink. I’ve replaced a few fans like these over the years after they failed in other hardware (granted that may say as much about their popularity as it does their quality). If I had my way I’d swap it with a Noctua (I have several in my PC which are approaching 100,000 hours with no sign of degradation, and their 40x40x10mm fans are rated at something like 150,000 hours MTTF and come with a 6-year warranty).

Not sure what pricing will be for replacements not covered under warranty. If it’s any help, the price listed on the invoice for customs was US$799.

It’s great that you can swap out the core optics on the new system, although one thing lost is that you can no longer clean the galvo (at least not without disassembling your LPU, which would likely not be sanctioned by Formlabs). I also found it odd that the top glass pane does not form part of the LPU. Integrating that component would mean you wouldn’t have to expose the innards to your environment during a swap, and would also help ensure the whole optical path is clean (mitigating a few more potential issues on troublesome machines). Not sure why after several generations of printers Formlabs shies away from making a truly permanently sealed optical housing. Must be a reason (maybe they anticipated shipping cheaper replacement glass window / roller assemblies more often).

Replacing the LPU is pretty easy. I also had one replaced under warrantee. Other than some fiddly cables, it wasn’t much harder than replacing the roller holder.

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has anyone had issues with the LPU replacement wizard skipping the laser calibration step after plugging it back in? I’ve ran through the wizard several times after replacing the LPU and it will initialize and then startup. When i go to prime a print it says it needs to recalibrate the laser using the wizard, but the wizard wont run the calibration process. I’m wondering if there isn’t an alternative to running the calibration without the LPU replacement wizard, but i can’t find that in any OS options.

I have this issue.

I described this issue to formlabs support. Ultimately they recommended me buying/replacing the LPU to fix since my warranty was over. pretty annoying to have to pay that much money to fix something that should work well beyond the warranty…

The new LPU did fix the problem, would have been nicer to have a cheaper fix

why not keep maintenance going?