Hello. I have been struggling with “flashing” aka “elephants foot” on the bottom layers of prints directly on the build surface. The current official solution is to change the z offset or adjust the exposure, but both of those adversely affect the first layer adhesion.
Proposed solution - X/Y scaling for the first few layers
This concept is implemented already in ChituBox (hobbyist slicer for Elegoo resin printers) and it works really well. It’s called “Bottom Tolerance Compensation”
How it works - the program just identifies the contours (inner and outer perimeters) of the model and offsets them inwards by a set amount for the first few layers that have increased power for layer adhesion. This effectively cancels out the elephants foot.
This concept is also ALMOST already built into Pre-form. Just combine the “early layer exposure and offset” setting with the “x/y correction factor” setting and you’ve got it.
Hello! This feature is actually already available for free on Formlabs SLA printers, through the Print Settings Editor (PSE) in PreForm. This tool allows users to adjust print parameters, including the early layer “elephant footing” offset you’re experiencing.
You can fine-tune this by going into the Early Layer Exposure and Offset section of the Print Settings Editor and adjusting the first layer’s offset value. In the example for Grey V5 on Form 4 at 0.1mm layer height, by default, the offset is set to -0.3 mm for the first layer. Making that more negative will increase adhesion but may worsen the flashing or elephant foot you’re describing, essentially creating a “brim,” like in FDM printing, increasing adhesion but potentially increasing the flashing effect. Adjusting it towards a more positive value will reduce the offset, making the elephant foot smaller, which is what I think you’re trying to achieve. You can experiment with this value and see if there is any tradeoff to layer adhesion for your specific use-case.
I would recommend changing early layer offset for the first few layers if you want to eliminate flash.
for example,
+1
+.5
+.3
You can learn more about the Print Settings Editor here. This feature is available for all users, and it offers control over print settings to optimize your results.
Please let me know if this proposed solution works for you as printing directly onto the build platform is the only way I get semi-decent results when priting square and flat things that need to line up with other sqaure and flat things.
Can you explain this setting a little bit further? I thought that setting changed the Z offset, but you’re saying that it actually changes the offset of the contour in the X/Y plane? And the reason that it might negatively affect layer adhesion is that it slightly reduces the area of the first layer, meaning there is slightly less area to stick to the build plate?
Can you confirm if the offset is just changing the x-y dimension or in the z dimension? Aditionally, what are the dimensions of the offset setting?
RHalvorsen also asked the same question. As the original poster expressed it would be great to just offset the x-y first layer pixels while leaving the z-axis settings unchanged to have both good bed-adhesion and avoid the elephant’s foot problem.
Not sure I would equate it to a brim, but this would be a nice addition (like a 200um brim) to help increase adhesion for build-on-plate geometries (I normally just design it in CAD but it would be a nice Addition).
To the formlabs team:
A lot of work has been done in the Hoby/comsumer market printers to eliminate the elephant foots problem. To be honest, I have not faced it in either the Prusa SL1S, Anycubic printers, etc and was surprised to see this on the Form 4 (which I got this past week, my first formlabs printer).
A user by the name of Jan Mrázek has done some great work/studies that shed light on uncommon causes of elephant’s foot, blooming, etc. I would highly recommend it to your team. I think you folks could adress this, particularly since print-on-plate is not encouraged by the introduction of the flexplate:
On resin viscosity and layer cure wait times as a preliminary cause of elephant’s foot:
Utilizing UVtools to modify print settings and eliminate elephant’s foot:
Slicers like Lychee have implemented getting rid of the elephant’s foot via x-y pixel compensation (what the RHalvorsen was suggesting). This setting is called “compensation” within the “burn-in layers” which is the equivalent of “early layers” in preform.
Thank you for explaining, my apologies still very new to SLA coming from FDM background.
Even in FDM in hardly ever used brims but like, instead design in “attachment support” for areas that needed it when printing with troublemakers like Nylon or ASA. On my Form4 I have not had any issues getting parts to stick to the build platform, but I have had to deal with Elephant’s foot which is a pain for various reasons.
Would be great if this can be addressed at some point.
The early layer offset parameter in the Print Settings Editor (PSE) adjusts the X/Y dimensions of the first few layers. It acts similarly to a “brim” in FDM printing, meaning that it reduces the “elephant’s foot” effect by slightly adjusting in the X/Y dimensions inwards for the first few layers. This adjustment does not affect the Z Offset at all.
When you increase this value (making it more positive), you reduce the “elephant foot” effect, but it can slightly reduce the adhesion of the part to the build plate since it reduces the surface area in contact with the plate. On the other hand, decreasing the value (making it more negative) can help with adhesion but may worsen the elephant’s foot issue, especially in cases where precise fitting is important. This information can also be found in our support article for using the Print Settings Editor
There are other options for Z Fine Tuning if you’re looking to change the Z Offset, but that is completely separate from what we’re discussing about the Elephant Foot settings.
Does that make more sense? Don’t hesitate to ask further questions!
Absolutely makes sense! I’ll try this out today and share results with everyone else to investigate the ability to remove the flashing/elephant’s foot.
Switching from the default -0.03 to a +0.02 successfully removed the elephant foot issue I was facing. WIth previous MSLA system this offset has been 0.0 when setting up sufficient delay times for the initial layers (see the link below). I believe the need to overcompensate with a +0.2 mm offset is due to the lack of proper delay time in these initial layers to let the resin fully settle before curing begins.
It would be great for the formlabs team to look into this alternative (increase settling/delay times before curing) so that for dimensional accurate parts can simply have a 0.0 mm offset rather than have to overcompensate.
In the meantime the early layers offset setting is the perfect lever to immidiately address the problem!
Great to know this, I will be sure to try this as well. I have been struggling to get the edge connecting to the supports to be 100% straight, printing on the build platform solved this problem but then I was stuck with the elephants foot problem. Hopefully this can work for me as well
No, the setting I’m referring to is under “EARLY LAYER EXPOSURE AND OFFSET” and is an array. I have screenshots of the setting above here. The ones you screenshotted I believe are global correction factors, calibrated to each material to compensate for shrinkage during the printing/curing process.
The one arrow indicates some elephants foot still present. The other one I have no idea what it is or why it happens. My current “EARLY LAYER EXPOSURE AND OFFSET" settings are as follow:
Just wanted to say - I noticed a small amount of elephants foot on some parts I printed today without a raft or supports and was going to start a topic requesting a compensation feature. Glad to hear one already exists, along with some other useful parameters to tune.
@henryqiu Thanks for those tips and screenshots. I noticed the “Early Layer Exposure” setting is missing an “Offset” capability when editing material profiles for the Form 3 series of printers:
Was that an oversight, or is there some kind of hardware limitation preventing its inclusion?
Any chance you can submit a feature request for me to backport this setting to the Form 3/3L? It feels like it would be incredibly useful. Elephants foot was a nagging problem that I really struggled with on my Form 3 and 3L, and is a major reason I still gravitate toward my Form 2 instead for prints that are sensitive to it (where I was able to “tune” it out via a combination of print bed and Z-offset adjustments, before Z-offset was available on the Form 3).
