Extremely long exposure times - Help!

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Tremfan
Posts: 5
Joined: Sun Nov 27, 2016 4:09 am
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Extremely long exposure times - Help!

Postby Tremfan » Sun Feb 05, 2017 3:04 am

Hello,

I got an unassembled Kickstarter LittleRP kit from a family friend a few weeks ago, and purchased a Viewsonic PJD-7820HD. I have finally assembled the kit, focused and modified the projector, and have been trying to get it to print for the last few days with the little bottle of Makerjuice SF red that came with the kit. I have the projector at 50% brightness with eco mode turned off, and my last print was .05 layer height with 35 second layers to even partially cure the resin - Small features still aren't showing up and it seems to me it's due to the resin still not being cured enough.

What am I doing wrong? Is Makerjuice SF supposed to take 40+ seconds to cure? Even the LittleRP rook takes 7 hours to print with those exposure times.
Should I try turning up the brightness? I'm worried about being left with a solid brick of resin if I do that.
Attachments
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C3DC
Posts: 9
Joined: Fri Feb 03, 2017 11:28 pm
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Re: Extremely long exposure times - Help!

Postby C3DC » Mon Feb 06, 2017 2:22 pm

Definitely shouldn't be taking that long to cure.

I'm not familiar with that projector but did you remove the the UV filter from it? That will definitely help. Also is that a brand new or refurb unit? It may need a new bulb.

goopyplastic
Posts: 236
Joined: Sat Mar 29, 2014 6:16 pm
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Re: Extremely long exposure times - Help!

Postby goopyplastic » Mon Feb 06, 2017 2:32 pm

How old is the sample bottle? There is a shelf life and it may have lost it's reactivity.

Also confirm that you are using .05 and not .5

Is this with the flexvat or pdms? if it is with petri / pdms did you scale the rook down before printing? default size is too big for pdms. Is there any popping / noises when printing, noticeable sticking?

Tremfan
Posts: 5
Joined: Sun Nov 27, 2016 4:09 am
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Re: Extremely long exposure times - Help!

Postby Tremfan » Mon Feb 06, 2017 4:25 pm

According to the shipping label, the kit was shipped in December of 2015, so the resin would be the same age. I do have the flex vat, and I have scaled the rook down to approximately 20x20x40mm. I am using .05 layer height.

No noticeable sticking/popping that I can tell. Looking at the bottom of the flex vat when the projector turns off and the plate lifts, the piece seems to just peel off the bottom pretty easily.

The projector was brand new, sealed in box. There are now about 25 hours on the bulb. I have not removed the UV filter, as it wasn't necessary for my model of projector from what I saw. I did see someone else on the forums remove the colorwheel in a recent posting, so I am designing a 3D printed bracket to do the same thing which I am hoping will decrease my cure times.

goopyplastic
Posts: 236
Joined: Sat Mar 29, 2014 6:16 pm
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Re: Extremely long exposure times - Help!

Postby goopyplastic » Tue Feb 07, 2017 12:44 pm

I wouldn't remove the color wheel or uv filter, it should be fine. That projector should be around 6500ms per 100micron layer with SubSF for LittleRP. If you are in the US, I can send you another sample bottle to try.

Tremfan
Posts: 5
Joined: Sun Nov 27, 2016 4:09 am
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Re: Extremely long exposure times - Help!

Postby Tremfan » Wed Feb 08, 2017 12:55 am

That would be fantastic, I will send you a PM. I'm located in Seattle.


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