Cartridge change leads to layer-shift

Hey everyone,

I’m new to the Form 3 (and Formlabs in general), and I’m starting to feel pretty frustrated. I’ve previously worked with hobbyist-level 3D printers, so maybe I had higher expectations for the overall performance and ease of use with the Form 3.

I’ve been running prints daily, and most of them max out the build volume. However, I’ve already wasted nearly a liter of grey resin, and at €160 per liter, that’s a pretty steep cost for such an expensive machine. The main issue I’m facing is that every third print or so runs out of resin in the tank, but the software doesn’t provide any warning.

If I try to change the cartridge mid-print, I end up with an unacceptable layer shift, which makes the print unusable. Also, it’s frustrating because the cartridge still has about 1/3 left, but I can’t seem to swap it out without causing issues - so thats just waste?

So, my questions are:

  1. Is there something wrong with my machine or my workflow?
  2. Is this just the nature of the Form 3, and I need to accept that the resin costs are unavoidable?
    ( or: im just too poor to throw photosensitive goop at it thats more expensive than blood?)

Any advice or tips would be greatly appreciated!

Thanks in advance!

Cheers,
Raph.

Hey @MONTUR,

Thanks for taking the time to post! I’m sorry your experience with your Form 3 sounds like its been frustrating.

Ideally, The printer should throw a gentle warning in PreForm when you start your print with a message that you may run out of resin during that particular print. Can you confirm for me if you’ve ever seen that type of message in PreForm as you’ve gone to start a print job?(Particularly before one of those jobs that pauses)

As far as the layer shift line goes, you’re absolutely right that if a print pauses for too long(like running out of resin for example) you can see that reflected in the print. That being said, in my experience those lines have mostly appeared when that pause is more than a few hours long. If you can swap a cartridge relatively quickly that will mitigate the layer line most of the time.

Are you running into a situation where that pause might be happening in the middle of the night, so when you’re able to get to the printer, it’s already been stopped for a while? That may be something to investigate just in terms of how you’re timing prints. However, I realize you’ll only have so much flexibility about when things are printing, so that’s not a catch-all solution.

Here’s what I might recommend moving forward.

  1. If you think there’s any risk of a print not finishing, I would preemptively swap out your resin cartridge to one that’s full, just to minimize those risks as best you can.
  2. BUT, I realize that leaves you with some spare resin in a tank, so given that if you end up with a few cartridges of resin that are 25-50% full, then you combine those resins into one cartridge, and then use that one to minimize any resin waste.

Typically I wouldn’t advocate for this(we don’t recommend pouring resin into another cartridge), but given your particular use-case I think it might help.

NOTE: If you do this, Preform might at some point throw a message that a resin cartridge is running low when it’s basically full. this is because the printer tracks the time that a particular cartridge has dispensed resin, so if you add resin back into a cartridge, you’re artificially extending the life of that cartridge. You’ll be able to ignore this warning in Preform if you see it, but you might see it.

I hope all that helps! Please let me know if I can dig into more detail on anything!

You should try to fix your process a little regardless of the brand. See how much it requires to print your items and see if that will go over the amount in a cartridge. If so, make sure to split the print up a little. You can also reuse the resin by pouring into the tank or into another bottle of the same type. There’s also a way to use a larger resin tank with a pump.

Those are some really insightful answers—thank you, Guys!

@DKirch, I have gotten a low resin warning in the past, but I think you’re right: it’s usually several hours before I can swap in a fresh cartridge in the morning. However, I’m curious why the printer would lose its position after just a few hours? The Form 3 uses linear rail and stepper motor? With proper pretension and backlash compensation, it shouldn’t really lose position like that, right? Or am I misunderstanding? I’m just curious at this point.

Anyway, I’ll run a small test print with an almost empty cartridge and swap it quickly to see if that helps. I’ll also try to schedule my prints more effectively—seems like a good starting point.

That said, I have to admit I’m a bit disappointed. I’ve had these kinds of problems with lower-grade printers, and I started using the Form 3 specifically to avoid dealing with these issues.

Cheers,
Raph

However, I’m curious why the printer would lose its position after just a few hours?

Great question! It’s actually less of any movement from either the print or the printer. Typically the cause for that line is more in the thermal end of things. A print sitting above the resin for a few hours will have the opportunity to cool/shrink/settle for a bit, which means that when the print restarts you basically have an old “cold” layer being connected to the new “hot” layer and that difference can manifest in that line you’re seeing. I’m simplifying this a bit, but that’s the general idea.

This doesn’t really affect the final strength properties of the print in any way, but it definitely can cause aesthetic issues from time to time.

I sincerely apologize for the general frustration with your Form 3! I hope I can help smooth things out a little bit for you so we can really dial in these processes to work for your projects.

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