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.
@RHalvorsen -
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.
Regards,
Friedl
Hi Henry, thank you very much for your response.
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?
Am I understanding this setting correctly?
