Top-Down: Surface Noise

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Jaidek
Posts: 23
Joined: Mon Jul 04, 2016 11:00 am
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Top-Down: Surface Noise

Postby Jaidek » Wed Sep 28, 2016 2:43 pm

Hi All,

I've recently completed my custom, top-down SLA build and I am currently in the testing phase. One thing I have noticed from a few of my test prints is that the layers aren't cleanly defined, more noisy or wavy. The whole surface has a bit of a grainy texture to it. What could be causing this? Overcure? Undercure? Rest time?

Here's some more information about my setup:

Top Down / Salt water floated resin
Resin: MakerJuice G+ w/ Grey Pigment (same grain on MakerJuice SF Red)
Projector - Acer X152H
X/Y Resolution: 0.05mm
Z Resolution: 0.06mm
Exposure Time: 10000
Bottom Exposure Time: 14000
Lift and Sequence: 10000
Lift Distance: 3mm
Z Lift Speed: 75
Z Bottom Speed: 75
Z Retract Speed: 75

Image
Image
Image

Any help would be greatly appreciated! :D

Jaidek
Posts: 23
Joined: Mon Jul 04, 2016 11:00 am
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Re: Top-Down: Surface Noise

Postby Jaidek » Sat Oct 01, 2016 11:02 am

I am continuing to do tests, this last few I've lowered the exposure time and increased the settle time a bit. Noise is still there and the only thing reducing the exposure time did was undercure the part. Next test is to go higher in exposure times. After that I will try a container of pure resin to see if the saltwater has affected its quality.

One other thing I need to factor out is that I have a VGA to HDMI converter running from the laptop to the projector. I might have to lug the printer into the computer room and try it on my desktop with true HDMI out.

Lastly, this forum seems to be a ghost town nowadays. Has everyone moved to another forum for DIY SLA printers? Or just the interest and knowledge has peaked?

Thanks!

rkundla
Posts: 17
Joined: Mon Jul 27, 2015 2:27 pm
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Re: Top-Down: Surface Noise

Postby rkundla » Tue Oct 25, 2016 5:03 pm

Bottom up rely on the non-stick interface material for the quality of the surface finish. In top down, it would be the liquid surface. Are you perhaps getting any ripple on the surface from air currents maybe or some sort of vibration?

The output of the video could be noisy, but I'd think that would average over the exposure because noise is essentially random. To get that consistently, you'd have to have that all the time, which would be a compression artifact or something similar. Maybe a setting on the projector?

Just throwing some ideas out there for you to chew on...


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