prints sticking to bottom of petri

[seravi]

My first prints came out great using the provided MadeSolid resin using the default settings described in the youtube video for setup. I went out and got some MakerJuice SF Red. I tried the settings listed on the site, and the print kept sticking to the bottom of the petri, destroying the print and the coating on the first dish. The print looked less defined, which I am guessing is a result of the overexposure. I read someone having better success with 2000ms, so I changed the settings and tried again. Still had sticking, destroyed another dish and print. Print was better, but some details were still less defined. Went back to the settings used the first time (1400ms), sticking was far less, destroyed another petri dish bottom but at least the print came out.

So in one evening I went from a near 100% success rate to nearly 0%. It sounds like even 1400ms is too long as a layer exposure? Why is that so different from what is on the site? Should I give up on MakerJuice?

[Scatterplot]

It sounds like your initial layers are too short OR your build plate isn't level. How confident are you in the levelness of your build plate? Did you rough it up before using it?

If you don't cure long enough, the layers won't stick to the plate. It sounds like you're undercuring, not overcuring, but I'm no expert here.

[seravi]

Hmm. I think part of the problem is that I didn't realize that MakerJuice SF is not the same as MakerJuice SF for LittleRP. The prints with the MakeSolid were fine, which is why I think the plate is level. The base layer is fine, the problem seems to happen about 50-60% into the print (where one of the parts is thickest). When I remove the plate after the print, there is cured resin stuck to the PDMS. Would that be from undercuring?

[seravi]

Oh man, I just realized why my description is confusing. It sticks to the petri dish AND its still on the build plate. As the plate moves up you hear it go thwack as the print separates from the bottom of the petri dish. Once it gets past the middle it stops making that noise.

[cerriousdesign]

Overexposure was my problem when I had prints sticking to the petri.

[seravi]

I reduced the exposure time and so far so good. What happens when its underexposed? I'll probably have to experiment a bit to find the sweet spot I suppose. Are the resins pretty consistent?

[goopyplastic]

Two things you will see when overexposing

1) Small features will start to fill in, basically the print will grow as it overcures. Riding the line between undercurring and overcurring allows for best detail reproduction.

2) PDMS life depends heavily on proper cure time, overcurring will make the layer stick more which will start to degrade the PDMS much quicker (can be seen as a fog / haze in the PDMS.