I need help printing a large piece

Trying to print a 2U rackmount faceplate (19" x 3.5" x 0.25") in 2 pieces and the edges are curling up, making registration of the two pieces impossible.

The Story:
Just for context, I’m relatively new to 3D printing and have rapidly learned it’s not a plug and play application. Be nice to me and explain your answers.

The problem is that the prints are curling up at the corners. Not just a little, but lifting > 2mm off the plate. This only happens after about 4-6 hours, and then the print head starts carving troughs along the outer edge as it works to deposit filament in new layers.

The design is not just a faceplate, it’s got other stuff on the back to hold various equipment, but I’m printing it face down. The plate is split into two pieces, the larger of which is about 11" long. I rotate it about 60 degrees to keep it more centered in the print bed. The two pieces need to print accurately in order to register to each other.

As near as I can understand it, the source of the problem is uneven heating/cooling of the model as filament is deposited, which creates an internal tension across the upper layer causing the piece to curl inward. I can reproduce it on some small pieces in high-quality print mode, but it does seem that faster and smaller prints suffer the phenomenon less.

I’ve tried:

  • keeping the enclosure sealed up, and opened up for full airflow
  • adjusting the nozzle temperatures up and down
  • adjusting the nozzle fan speed down (this is NOT a good idea FWIW)
  • changing the bed temperature up and down (initial layer and other layers)
  • I meticulously clean the print bed for adhesion
  • I’ve messed with print speeds a lot, but I want a high quality result…
  • I’ve messed with infill some, and the thickness of the top and bottom layers.

The only thing I haven’t tried from all the various troubleshooting lists I’ve looked at is spreading glue on the build plate. That feels like a last resort and not a viable long-term solution.

I’m about at wits-end. I’ve tried many many prints and have a trash can full of bad starts. I have gotten one usable piece, but even that one was still… poor.

What advice can you give to get a good result on a big piece like this?

If you haven’t already, try printing with a brim (ideally a wide one). That should stick the corners down. The edges may need a little cleanup afterwards, but having to make a quick pass with sandpaper is better than printing a lot of unusable parts. (Also, I’m assuming you’re printing PLA. If you’re trying to do this with ABS or similar, well, don’t.)

And the glue thing is not a last resort (in fact, it can be a necessity with certain combinations of filament and plate material—PETG can be a bit of a pain to pry loose without it, for example) and is just fine as a long-term solution.

You didn’t say what filament you’re using. If it’s PETG I personally don’t print without glue stick (and usually with PLA). Some people will try and shame you or say it’s not necessary if you’re properly calibrated, but it just gives you a little extra margin of error. It’s super easy and quick. I like the big Elmer’s that’s purple until it dries. Lay down a thin layer covering the print area and you’re good to go for at least 4 or 5 prints (minimum). When you’re done you just rinse your object and the bed off under the sink.

Make sure you turn off your enclosure fan. That can help with warping.

Brim is good suggestion.

Have you calibrated extruder/e-steps? If you’re under extruding you’ll have adhesion problems. Or if your first layer is too high. Share some pictures of first layer.


  • I’m printing with basic PLA, I haven’t tried to venture out on materials yet.
  • The enclosure vent fan is off
  • The extruder needs separate calibration? I need to look that up. I’ve had a lot of adhesion problems and have generally been unhappy with the print quality on the first layer as I get strings all over the place, even when I’ve calibrated the print head to be right down on the bed and use a very slow first layer speed.
  • part of the reason I’m skeptical on glue is that all the glues mentioned in various online guides are basically liquid when heated. Do they work because they cool down after the first layer?

I’ll look up the extruder calibration, try the brim, and I guess I’ll get some glue (LOL).

PLA does not like heat. If your bed is above 50°C, or the enclosure is closed, you will not get enough cooling. PLA needs a lot of cooling, and physically sets within ~20 seconds of being laid down, if you are doing things right.

  • The hot end should be around ~205 °C.
  • The bed should be at 50°C or lower. No bed heating is required.
  • The part cooling fan should be at 100%.
  • The doors must be at least partly open to keep the ambient temperature around normal room temperature.

Whomever told you that the glues used are liquid at the temperatures that we are talking about, doesn’t know what they are talking about. PLA does not need glue stick, but if you do use glue stick, use the Elmer’s Purple/Invisible glue sticks. Do not use anything that is white, as it contains acids that will cause problems, including the destruction of your build surface.

Not necessarily true, but acid-free white glue sticks will be labeled as such somewhere in the fine print on the tube.

I appreciate the clarification. I also appreciate the dogmatic viewpoint for a beginner. :wink:

I agree with what was said here, but I’ll throw in an additional tip as well. The edges of the bed take longer to heat than the center, which for large prints can cause uneven adhesion. I’d recommend setting the bed to your first layer temp and leaving it for 15-20 minutes before starting the print to make sure the edges of the bed have warmed up to temperature.

You’ve gotten a lot of good advice already - I’ll just add to think of this all as stress relief as filament cools. The deposited ‘strings’ will contract along their length axis more than thru their ‘thickness’, so in a square with 3 or 4 rows of ‘outlines’ the corners will lift the most, and in a long rectangle the short ends get tugged. A couple bottom skin layers will want to do this already, when you stack more perimeters around that, and a top skin also wanting to contract, it exacerbates the problem.

You might also try, if your design can allow it, things that would reduce the long straight line runs of extrusion. No promises it will SOLVE the problem - or prevent warping later if the part is exposed to heating or cooling differentially - but it can help. I’ve tried:

  • rounded corners
  • fewer ‘outlines’ (side walls)
  • breaking up the bottom and top skin faces into a grid of squares with like a 0.5mm wide slot, 2-3 layers deep, between them (and obviously no support)
  • a pattern of holes thru large rectangular plates that get outlined individually, but also break up the diagonal line pattern fill
  • ‘crenelating’ the outer perimeter, so there’s more ‘edge length’ and it’s not a straight line to contract in one dimension

Obviously all of those will influence the visual nature of the finished product, so might not be acceptable solutions…and none of them eliminate the problem entirely, but they all should help some. Dropping your infill percentage and/or switching to one of the infills that doesn’t “stack” structurally can also reduce the pull of those layers thru the thickness…which can be as bad as it is good if the top finished large face ends up ‘tugging’ …all the suggestions for the bed-contact face would also need to apply for the top too (but I repeat myself…)

Thank you Richard, this is a fascinating idea.

If you’re using cura you can change the infill pattern. Different patterns work better for different shapes and strength needs.


Summary of my current steps:

  • I looked up e-step calibration and performed that (it was under-extruding by about 9%)
  • I added a brim to the print
  • I preheated the bed
  • I have opened up the area to ensure good airflow

I still have not added glue to the regimen, just because I don’t have it here. I will pick it up next time I get out.

My latest test run is in progress using a faster print setting, so I’ll see how that turns out and report back.

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The test print without glue, but with the brim, stayed flat and true - however the bottom face had an inexcusable number of voids and burs where the first layer did not adhere around openings. I applied glue and did a test run of just the first few layers. When I peeled that up, it looked extremely clean, though I will likely still have to apply a filler to get a smooth, paintable surface.

I slowed the first layer down even more and have dropped the print head temperature 2 degrees to try to reduce some of the minor blistering. That “high quality” run is in progress now.

One key question I have is: why isn’t any of the information from this thread in the official documentation from snapmaker? Calibrating the extruder seems like a required action that is nowhere to be found, and I’ve tried so many things to get better adhesion… I mean, they could include a stick of snapmaker official “bed adhesive agent”, and sell it as a consumable. Either the need for these things is suspect, or there is a significant set of gaps in the snapmaker documentation - which is otherwise so good that it’s hard to believe…

Are you using the SM PLA? The quality of the SM filament is known to be inconsistent at best. They don’t make their own. Their original supplier was awful and it seems to have been improved, but there are plenty of better and cheaper places to get your filament than SM.

The problem is SM continues to be determined to market the SM as plug and play - that it will work straight out of the box and Luban is a do-all software. The truth is that that just isn’t how 3d printing works. If you look at the manuals for pretty much every other 3d printer manufacturer they have a set of instructions for calibration that you need to follow first. There are hints and tips for how to troubleshoot and improve quality. Unfortunately SM doesn’t include this info. So a lot of people have troubles that could be avoided with a little effort.
What SM includes in their documentation is fairly well written. It’s what they omit that’s the problem.
Use of a glue stick, magigoo, painter’s tape, hairspray, special bed surfaces etc. are all a normal part of 3d printing. There’s nothing suspect about them.

@brettonw the only thing that I can add is that of us original Kickstarter contributors, we had at least 12 months to read up on and watch videos for CNC 3D printing, CNC milling, and CNC lasering. I purposefully added CNC to everything, as those are the true full names. Getting into CNC is not something that should be taken lightly, and isn’t something that you can just do on day 1. If you don’t have any background at all in CNC, expect a long journey.

I was actually introduced to it way back in 1986, when I was an Electronic Engineer working on electronic weighing systems for government contracts, aerospace, and commercial systems. We had multiple CNC drill presses, a Mitsubishi wire cutting machine (cuts metals of all types and thicknesses), and multiple milling machines that were being upgraded with CNC controllers. This helped a lot, as I knew what to expect, and many of the issues that I would run into.

The 3D printing was new, so I spent a few hundred hours watching videos from well known content creators and reading as much as I could, to learn the process. My electronics background helped me know what to question, so I didn’t take everything at face value, and there is a lot of inaccurate or false information out there. As you learn, you’ll be able to filter this out for yourself.

As for Snapmaker, we have tried to make this information available to Snapmaker to include in official guides, and we were making a lot of headway with Edwin, but then he left the company. Most of us pretty much gave up on the endeavor at that point, and decided to just try to help those who really want help. I believe that you are one of those people. There are many who ask for help, but don’t really want it, and ignore good information.

The old adage, Learn one, Do one, Teach one, applies here, and most have fun working through the learning process. The only thing that we can’t do in these forums, is to offer Support for something that is broken. If something is broken, the only option is for one to contact Snapmaker Support directly. Snapmaker does not open tickets from these forums.

Best of luck!

In as much as any OEM can document all the “best practices” known to them, any average user will find a problem not covered in the documentation. Average is novice to expert here.

In my experience, that is what user forums are really for. Supplementing OEM documentation.

The best systems with the best documentation, and from what I’ve seen, Snapmaker is on the high end of that spectrum, also tend to have a more experienced forum population eager to help.
Many take a user problem to heart and doggedly try to find a solution.

This thread is an excellent example of that.

This is an excellent suggestion too. I know long ago when you started it print it seemed like it heated the extruder and bed in parallel…and the extruder heats up a lot faster, so the print ended up waiting with a hot extruder. From my own older printer and ABS I didn’t like that, seemed like a recipe for ending up with cooked crud and blocked nozzles.

So I always heat up the bed first manually, then once it’s at temp or a few minutes thereafter, go back to ‘Files’ and pick my file off the USB to print. In my case I started this method to ‘save my nozzle’ but also has exact effect you mention of helping the bed get there out to the extremities before the print starts.

I don’t even know if later software has done a better job of heating the bed first, because this is just my habit now.

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This has nothing to do with the firmware in the printer, it is solely controlled from the START and STOP G-code that is defined in the slicer. I always modify this G-code to meet my needs. Also, pre-heating is a practice, which is not something that any printer does by itself, it is manually performed by the operator.

Did I say firmware?

I could have clarified, sure, that I’m just using Luban as my slicer so relying on its start and stop G-codes. Which can also have been modified version to version.

But ok, thanks for the precision.

Having taken all the advice here, from calibrating the extruder and preheating the bed to using glue on the bed and printing with a brim… The sum of all these things seems to have solved the curling problem. Thank you to everyone who helped me.

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