Overcuring - Calibration of a resin

[Mario]

I had a bit of an issue with a model that looked molted on the support side. Asking around in the facebook group we resolved that it was due to overcure - too much time per layer.

I printed the calibration matrix from thingiverse: https://www.thingiverse.com/thing:165389 at different settings.

What I found out, is the longer you set the exposure time, the more molten/blurry the end result will be. Until you meet a threshold where small details just disappear and end up as a blob on your FEP.

Here are the results. 10 seconds was too low. Anything above 25 secs resulted in an overcured mess. 15 seems to be the sweet spot for the Photocentric firm white at 0.05mm (0.04mm works too, I tested)

So when you get a new resin, it doesn't hurt if you print a few of these at different exposure times maybe also resolutions to get started - the also print very, very fast (10-25mins)

[Mario]

IMG_4499_resize.jpg (116.92 KiB) Viewed 875 times

IMG_4498_resize.jpg (124.67 KiB) Viewed 875 times

IMG_4497_resize.jpg (126.46 KiB) Viewed 875 times

[Mario]

All of them:

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[Mario]

The 10 second piece, with a lot of details missing. It's on the FEP

IMG_4510.JPG (76 KiB) Viewed 866 times

[jfabritz]

What you find is that the more UV light you provide the resin, the further the crosslinking occurs beyond the masked regions. This creates the blurring of fine details. However, that is not all you are seeing here.

Based on your example photos and commentary I think you are seeing is bleedthrough on the mask and it is enough to activate the resin enough to cause this blotchy curing of the resin. From my experience, LCD-based printers can suffer from this bleeding effect because the LCD is not able to provide enough contrast ratio between the exposed and unexposed portions of the mask.

[men8ifr]

That test print looks simply awful - no detail at any exposure time. I've heard some resins are very very bad - maybe you have one (what was it). I would suggest going back to the Anycubic resin for reference and if that comes out good throw the white stuff in the bin.

[Warnerrerce]

It sound nice.
Would you please put some picture of samples printed by this resin and casting results?

Thanks