Ability to turn off the initial layer compression for flat printing

There is definitely variation in thickness of different tanks, however they all seem pretty level. However I have measured using an inclinometer the difference in angle between the platform and the tray housing on all 3 machines I have had and all 3 have been off.

As for level adjustment screws that would work if they calibrated the machines so the lasers drew the path undistorted on the surface of the platform, but unfortunately from my discussions with them I’ve gotten the impression they calibrate them to draw it undistorted on the surface of the tray. This means if you adjusted the tray to be parallel with the platform you would introduce distortion to your prints. Which is a real shame as there already are screws you can adjust to level the tray housing. There is even a YouTube video demonstrating the process.

My other thought is maybe the build platform walks just a little and it isn’t the tanks so much.
I had to adjust the tension on the lock clip already on mine. If that isn’t parallel then you would have the skewing. To me that seems more like the culprit rather than the tank being off itself.

If thats the case then it would be easy to use some shim stock between the aluminum and head to tweak the size.

Still want to be able to turn off the compression layers when no supports are used. Sounds like the easiest fix.

Yeah with just rough measurements with my inclinometer in the past, it seemed if you assume the column housing the threaded rod runs reasonably parallel to the z-axis that the plane of the platform was quite close to perpendicular to the z-axis, while the plane of the tray housing was not.

The important thing to avoid skewing is that the planes are perpendicular to the z-axis. I’ve explained they have not been on any of my machines and Formlabs has assured me this is all compensated for in the calibration process, and that this process takes place both in the factory and in the software, but they can tell me no more. I can detail more of the extensive conversations I’ve had but to some it up after much poking and prodding and extracting data that May or may not be correct I’ve come to some theories about what they do to 'calibrate" these machines but they refuse to admit or deny any of it. One thing they have openly admitted repeatedly is that making the platform and the tray parallel is not a part of the calibration process, and they don’t even really try to do so.

If your platform is loose tighten the screw in the top some it should be snug and stable. I will check my measurements again tonight. You can check your machine pretty easily if you would like. Most smartphones these days have bubble level apps if you don’t have a digital inclinometer.

Are all your tanks different?
I made a small disk .1" thick and can repeat that model around the tank and measure the thickness of each to compare.

Four of that model, one in each corner, should suffice. Also my tanks have definitely varied in thickness, but only slightly. Also like I said they all seem to be really even thickness. I also rechecked my machine with my inclinometer and the plane of the platform is quite close to perpendicular to the z-axis, while the plane of the tray housing is way off so it is definitely the tray.

Makes sense then why they use the compression layers to compensate for any small variations in tanks.

Yeah although the variation in height due to tanks being non-parallel is a bigger problem. I’ve only seen about 0.2mm difference in thickness across about 5 tanks, however there is about .85mm diffrence in thickness between different corners of my print area. So they need to compensate for slop from calibration more than variation in thickness.

In my opinion this advanced user, special-case, highly dangerous feature has zero chance of being added. I know it sounds handy.

@JoshK they already have for the most part it’s called z-offset. I would like it if they gave us a greater height range. It’s just not a simple as turning it off, which is what most of the conversation has been about. It’s also not highly dangerous.

Increasing the z-offset range is a good idea would be awesome. And the result of it would be the same as the feature mentioned. And since going too far is easy to understand I wouldn’t call that dangerous at all.

Another idea for solving this is to refurbish your own tank and adjust the thickness of the PDMS to your liking.

Hey that’s a great idea and it would save on slygard too! It’s going to be a while before I order more and try that but I definitely will! I’m still trying to find a cheaper source of the Slygard 182 but if I can’t I’ll just stick with using 184 from MLSolar I already emailed them asking but they cant get 182 but they said the longer the 184 sets up the harder it gets so I’m just going to let my re-coats sit for a week before I use them. I get best results with an 80/10 mix so I’ll try a tray with half and see how it turns out.

Is this the same silicone as Sylguard?
From Smooth-On

It’s not the same but maybe it would work I don’t know?
Best price for Slygard is here: http://shop.mlsolar.com/Sylguard-SG1K.htm

Smooth-On is a little cheaper. Not sure if the bonding primer is useful.
In any case it’s probably not worth going though all the work because the tanks are pretty inexpensive.

Maybe down the road when I have a box full of them I might consider it.

I just have two that I’ve been re-coating but a Slygard kit does five coats
and is way way cheaper than buying five tanks! $57.25 vs $310.08
I would very much like to hear any reports on the Smooth-On though!

Sounds like you could set up a service, take in peoples old tanks and re-coat them…

Considered it but after shipping and with all the wait time so lots of space, and with all the potential for being blamed for print failures I decided no way! It would be alot different if it was just locals but I dont know of anyone even in Indiana…

I’m also interested in this- we generate a lot of haptic perception experiment stimuli and I’ve not had a ton of luck printing flat for many of the reasons outlined above. The support we’ve received has also been rather ‘broad’ with respect to what is going on with respect to calibration. Sorry for a ‘me too’ post , but wanted to make sure to add a voice to those wanting support (cough) for this.

Hey for those of you interested in Formlabs expanding the z-offset range, I have created a new feature request here please take a moment and post in it that you also want this feature. Maybe if enough people express interest they will do the tiny little mod to the software it would take to implement it.