Cannot figure out how to print certain STL files

Hello everyone. I bought the Form 2 last year but did not receive it until February so I have had a small amount of time working with it. In the beginning the STL files that I printed worked out great although I had some issues with trying to print multiple objects. Overall I was happy but a little frustrated. Over time as I received new STL files and tried to print them I consistently had misprint after misprint and can’t seem to figure out what is wrong.

At this point I would like to post my issues in the hopes that someone could teach me or assist me on how to improve my successful print rate and ensure I don’t run into these problems in the future. The supports begin to print fine then at some point during the printing the print fails and I am left with some supports and a lot of plastic stuck to my tray. I would be happy to share my STL files for anyone willing to look at them. I believe there are 3 files that are causing me a lot of stress and pain. :slight_smile: Thanks and I look forward to your replies. You can also email me at



First question is - are the files watertight? I use Netfabb (Basic or cloud are free) to check files before printing - and while I’m aware that there is a subset of Netfabb codebase in Preform, I don’t know exactly how comprehensive it is.

Second part would be can you still print a known STL successfully after a failed one?

Any stats on the failing models?

All very good questions. I believe they are water tight but not 100% sure. I am trying to print 28mm scale toy soldiers that are solid pieces.

I have been able to print other STL files successfully. I think I might have ‘floaters’ or parts of the print that are not attached to support trees but I am not sure.

How would I go about pulling the stats for the failed prints.

Please forgive my ignorance. I am learning but very slowly. :slight_smile:

Hi Joe,

Have you “swept” the tank for tiny cured particles with a fine tooth comb?

Are you current on the firmware and software updates?

Water-tightness is a good point to check. I use Netfabb too.

I just received my Form 2 last week, but have not had a single problem or failed print so far. (knock on wood)

Are you opening the flip cap on the top of the resin canister before beginning the print? If it stays closed, the vaccum effect doesn’t let the resin run into the tray properly…do you have resin in your tray when a print fails?

Hopefully, you work it out soon because we’ve got amazing machines.



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If you download Netfabb Basic (free) you can import your models into it & run a repair script on them; that’ll tell you if they were watertight (I’m assuming you know what I’m on about here?). It’ll also tell you what it thinks the volume is, how many polygons make up the file & the parsed overall dimensions.

As far as floaters go… Strain the resin in the tray after making sure there’s none adhered to the PDMS surface. Instructions are available under Formlabs’ support pages; I use paint filters for straining resin.

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Yes, I am very anal about keeping my printer clean. I have swept the tank, filtered the liquid through a filter, etc.

My firmware and software is up to date. The cap is open.

It seems I haven’t checked for Water-tightness and based on my conversation with the tech team it seems like my supports may not be set up properly.

Thanks for the help.



I just downloaded netfabb and that looks like it will help. Thanks for that.

I am using the wrong terminology because when I refer to ‘floaters’ I meant that during the printing process there are sections of my object that are not connected to the supports and are just floating in mid air. I was told by the tech team that these disconnected pieces will cause a misprint. My problem with this is I am still learning how to establish supports and look for these disconnected pieces. Make sense?


PreForm runs a check on the STL when you import it. If it’s not water tight, has non-manifold edges, and I think also if there are “internal” shells, they are removed using algorithms I think FormLabs licenses from NetFabb. I’ve run in to situations where PreForm cannot repair a model, and some combination of the standalone NetFabb, MeshMixer, and MeshLab was able to effect the necessary repairs. But even if it can’t repair the issues, PreForm seems to do a pretty good job of identifying them, so if PreForm didn’t complain about the geometry when it was imported, odds are the geometry is not at fault for the bad print results…

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Espy, u are right, the paint filters as described on Formlabs is the best way to get resin ‘clean’ when emptying the tray.

Tho so far I’ve only used clear and black and just kept the extra ‘combed’ and left in the covered tray. I liked the advice I heard to pick up a tray for each resin. There’s cost, but simplicity itself to change resins. :slight_smile:

No worries. I’m glad there are other people here to talk about this stuff with.

Thanks all.

Oh, I JUST pulled this off the platform after 22 hr print job…going to bake it and hopefully a little knife and sandpaper work will get it turning.

I already had a batch of filters on hand from car painting, so it was a no-brainer.

I’m similarly using 1 tank per resin; when swapped out they go back in the box with the box labelled along the lines of “keep flat or wear it”… Life’s too short to clean resin tanks every time I swap - used to do that with my older printer. Currently using clear & castable but I’ll probably add black & tough sometime soon. I also have 1 spare tank with no resin assigned so I have an immediate spare on hand.

And - nice bearing. What clearance did you spec between bearings & races?

Thanks. I sized the model down by about 30% after I downloaded it off of Pinshape. Original spacing was 3 mm, so probably close to 2mm now. After printing, I put it in my “UV oven” (36W gel nail dryer) for 3 hours. The bearing has a thin self-support in the model at the bearing/race connection. I’m hoping an exacto knife can slice the creases to free the bearings and then sand (wet, 1500 grit) each bearing smooth.

That’s the plan. I should complete it before I go to bed tonight.

I’ll let y’all know and post pics.


So I believe the ball bearing object was printed correctly, but the supports underneath for the bearings are too solid to easily make it work. Maybe due to resizing I did, tho possibly model no good for SLA? Anyway, I’ll clean this example up and post pics in a separate string in a day or two.

In the meantime, I may try to hack the model with the artists permission for a useable SLA print. I’ll let y’all know.


The automatic support system does not always get the parts that have no supports, I always do an automatic supports generation and then go over it manually, you can get much better results by adjusting the supports yourself. Like I said sometimes it misses points but also you can arrange the supports better to get cleaner printing results.

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