I agree with you completely that Formlabs resin selection is simply unmatched, and depending on the industry and specific needs, the Form printers may be the only game in town.
But I still have to understand how the Form 3 LFS technology is superior. I’ve watched these printers print, and they still pull up on the print to separate it from the film. The only thing I can think of is that the LPU pressing on the underside an deforming the film slightly, acts a precursor to full detachment, effectively “loosening” the print from the film. But in my mind, that could cause lateral deformities in the print, since you’re not printing on a flat surface.
For myself personally, I still categorize the Mono X under the “hobby” category, but that’s a personal distinction.
I’m actually impressed that the contact size is 0.5mm, that’s not bad! Thanks for sharing that.
Are there good profiles for engineering resins out there? Or is it mostly low impact resistance modelling resins right now? And how much tweaking is required?
LFS works by tensioning the film during printing, and then releasing the tension before the peel process. This lets the part peel gradually as opposed to all at once. This results in lower instantaneous peel forces. The total peel force averaged over time is probably the same, but the importance is that the maximum peel force is less.
Think of it kind of like pulling a suction cup. If you pull it vertically it requires a lot of force and will eventually pop off. If you peel it from the side, it’s much easier but it’s slower.
Pennywhistles of performance grade need thou-level accuracy, and for the last year I’ve been very pleased with my Form 3. Resin quality control, perhaps not so much, but the LFS seems to really improve print quality. Some of my later clear prototypes were almost glassy.
During the peel action on a LCD printer with FEP release film, the print is pulled up by the platform, but it doesn’t detach all at once like it would from a suction cup. It’s actually a gradual detachment, because as the film is being pulled up, it deflects more in the center than at the edges, so the print starts detaching around the edges first, and gradually toward the center.
Having spent a lot of time over the last 18 months actually measuring the different amounts of force to separate prints in different resin materials from various surfaces you might want to consider the following findings:
1: FEP - V - PDMS . Resin adheres to FEP better than to PDMS (For a given surface area of 100mm2) the adhesion to FEP is between 1.3 and 1.8 times greater. The adhesion of PDMS to the resin gets less as the PDMS degrades due to UV light exposure.
2: FEP outlasts PDMS by a factor of approx. 180 to 1 (Its usefulness being defined as when it either degrades to 95% of the UV energy being transmitted through it compared to when the material is first used) - Think of the milky appearance of PDMS after its been used in a printer for a while. The milky appearance both lowers UV transmission rate and also causes diffusion, therefore a print will not be so sharp after a period of time…
3: Both FEP and PDMS need significantly less force in a shear motion to separate from the print rather than a simple (tensile force) pull.
4: Our conclusion is that a shear force combined with a small tensile pull results in the lowest force required to separate a print from either PDMS or FEP. Both forces should be applied at a similar speed with the tensile force being approx. 45% of the shear force applied for optimal separation.
5: The roller tension method deployed on the Form 3 is not greatly different to the system used by Asiga on its printers (albeit that Asiga started to use that method years before Formlabs).
I wonder why everyone has moved away from a shear peel. It was quite common back in the day. Maybe because of the deflection it causes, or because of the additional mechanisms required?
Obviously in the case of the Form 3, LFS is better than the shear peel on the Form 2 because I can print at 0.3mm instead of 0.5 or 0.6 like I used to on the D2.
Both. Initial offering is 3D printed, hoping to mass produce if popularity rises, retaining 3D printing for specialty and one-off “art project” models.
“Slide and seperate” sounds like what the Form 2 does (or did, some firmware updates ago) - sliding to the side with the tank while also pulling upwards.
