Miscalibration, circles turn into ellipses

I noticed that my printer seems to be miscalibrated. When I print objects that should have the same size in two dimensions, they are off, so circles turn into ellipses, for example. Below are some photos.

I’d be interested to know how accurate other Form 1 printers print such items. I used the file “2x_stages_kit.stl” from here: http://www.thingiverse.com/thing:23030.

I printed the set, but it will not work mechanically at all because the little gears for example will not turn on the rods at all as everything is elliptical instead of circular.

Hello Marc,

I’ve posted a topic on this topic here:


My printer display the same behavior,  I’ve also pushed a bug report, but have no specific answer yet.

We will probably have to calibrate the Galvo unless Formlab adds some corrective parameters in preform.


Thanks Damien, I also opened a support ticket. I’m hoping there’s some calibration procedure I can run through myself.

Good day Marc,

just got an answer from Jennifer’s on my bug request.

Apparently we are SOL for the moment (see in my calibration thread).


Thanks Damien, I heard the same, unfortunately. So I guess I’ll have to use it for non-functional things for now. I’ll be making lots of chess sets…

I wonder if this issue is rare or common. Perhaps we should publish a test model and ask other owners to print and measure it.

Can you please elaborate on being SOL for the moment. This does not sit well with me as I wait for them to eventually ship my printer. I will take a refund and shop somewhere else if they can not resolve an issue that arose between the extensive and exacting tests they put these machines through and it arriving on your door step.

WOW,  This forum software really does suck.  I can not edit my previous post.  Oh well, that is another topic.  I just saw what they sent you.  I will have to consider my options as that answer is pathetic IMO.  They should have issued a call tag, picked up the printer, re-calibrated it, and shipped it back to you all on their dime.  This holding pattern is not a professional way to handle an issue.

@ David,

My printer (I don’t know for Mark) was one of the first sent, and if you read the last update they are struggling with calibration.

I’m not surprised as galvanometers are notoriously complex to calibrate properly…

So until we have more reports from other users that the issue is widespread, you cannot rule out that we received miss calibrated printers.

I guess we are paying for the early adopters status. I’m confident Formlabs will find a solution in the end, but how long will it take? I didn’t got my Form1 to print Chess sets and figurines as Marc is saying… Pretty resolution for small details is useless if the linearity is completely off.

@ Marc,

for the calibration procedure, I’m sure they don’t want us to open the box and tune the Galvos amplifiers boards by hand as this could completely kill the performances. I’m just worries these miss-calibration might not be linear.

The easiest case is only a ‘range’ miss-calibration (ie the signals amplification a bit off), then scaling the X/Y axis in the STL by a few % should, solve the issue…

But if it’s dynamic then we cannot even compensate by scaling the geometry. Galvos are mechanical systems, so depending on the moving path they will have inertia and oscillations. If the system (form1) is not set perfectly then fast variations (like circular paths) will lag/undershoot. If these effects are not balanced on both axis, circles will appears as ellipses but simple linear path like the filling will work fine…

Writing this I’m wondering if this issue cannot be related to the Skin delamination failure mode. If the external paths are off, then the internal filling is actuality not touching the borders… Maybe a Formlabs employe could chime in?

I’ll try to do a calibration file, maybe something as simple as a cube with a cylinder on top could be used?


I think my printer was also a very early one, I was in the second batch (“SPECIAL PER-FORM-ANCE” on Kickstarter).

I understand that they have been experiencing calibration issues. I understand the issues associated with that. The piece that concerns me is, you have shown your machine has an issue. They have acknowledged it and now they said to wait. Would the answer have been different if the laser died or a galvo died? What ever way the issue is sliced, you have an issue and they need to fix it. I see this as a test on how they handle their warranty claims.

Thanks, Marc and Damien, for bringing this to our attention. We take enormous pride in the precision and accuracy of the Form 1, and we’ve made the issues your’e describing a top-priority internally. As engineers and researchers, its important to us that you can rely on the Form 1 as a tool and we’re doing our best to come up with good solutions.

We are continuing to make accuracy and reliability improvements through regular software updates.  We will also follow up with each of you through our ticketing system and consult with calibration data we have from the factory to determine if there is a manufacturing defect.  In that case, of course, we will replace the machine.

Thanks for carefully documenting these results.  Personally, I’ve been amazed at how serious our community has been in measuring the performance of the Form 1 and testing its limits.  We really appreciate it and it helps us a great deal.  I love beautiful chess pieces as well, but as an engineer, I know it’s critical to have a tool you can rely on.

Thanks a lot for this great response Maxim, this is very encouraging.

I am more than willing to give you as much time as you need to come up with a good solution, now that I know that it is recognized as an important issue. The initial feedback I got was not quite as encouraging.

Let me know what helpful information and/or testing I can provide.

Thanks Maxim, like Marc It wouldn’t be an issue for me to perform some advance calibration procedure if you provide the right soft/documentation (open the box & tweak the galvo amplifiers or run ILD patterns for example).

FYI I’ve measured the same ellipse effect on John Morewood printer pieces, so it seems to be present on more than 2 units…


Same problem here. Circles printed as ellipses 7:5.5 from the first print. Along with shift in X direction for 5/12 width of the printing platform to the left. Issued support ticket. Will see.

Photo of the skewed lego brick attached.

I am concerned about this issue. Considering canceling my order until this is resolved. What % of owners encounter this?


Andrey’s photo is definitely not normal and we are working with him to resolve it.  You can be confident we will make sure your printer produces much better results than that.  We are working on providing more exact specs for accuracy, but it is actually difficult to give general guidelines that apply across all kinds of parts, materials, print settings, etc.


Let me ask it here. If Formlabs ever do test prints on new/calibrated printers then you most probably have one or two standard test models with exact dimensions and acceptable margin of error. Why Formlabs just doesn’t publish these models and error margins?

It could somehow help new customers deciding about accuracy of the printer. It will definitely help current printer owners to check its printers calibration.

This question was asked number of times on the forum and in private messages but there is no answer so far.


You say that it is difficult to give general guidelines on accuracy.  I would like to know why it is so hard.  It should not matter what the part looks like.  You now have 2 materials available with 3 machine settings.  Seems simple enough to me.

I draw a cube 3x3x3.  That is how I expect it to print.  The 3D Systems Invision LD that I have prints a cube 3x3x3.  It might be a few thousandths off (maybe .003 in each direction).  What are the dimensions of this part if it was printed on a Form 1.  Based on the above problems described…

My decision to cancel my order hinges on this as well as a few other questions that I have been waiting over a week to have answered on a submitted support ticket.



I have yet to hear about a perfectly calibrated printer… Note, that could be fine if preform let us change the calibration manually to get at least the same scaling factor on all axis. But as one of the first backer to receive my printer, I can tell you I’m still stuck with an axis that has 1.5% scaling error on one axis.

That’s nowhere as critical as Andrew situation, but prevents me from printing any functional objects.


I had the chance to discuss quickly with you some time ago, and I will repeat it here, we as user are your ally. I understand that early adopters have to deal with details and quirks that should be resolved in an older product. That said without knobs and configuration/tweaking means we can’t help you making the Form1 from a sleek product to a killer printer!