FTD resin exposure times findings/help :)

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FTD resin exposure times findings/help :)

Postby Finhead » Fri Apr 04, 2014 1:24 pm

Still trying to setup my printer correctly, it seems to be mechanically setup fine but nailed down exposure on this resin is proving difficult at best.
Link to my latest prints. http://www.buildyourownsla.com/forum/viewtopic.php?f=9&t=1342

I printed both the shelled to 1mm Zombie Killer and solid model Devil at the same time to see the outcome for each since I have had no luck getting a perfect print with the shelled models I have. My take on it (being brand new to resin printing)
Shelled prints take a longer cure time when all things are equal to a solid print, and vise versa. The shelled model has holes in the very thin areas which would tell me the exposure time needs to go up, correct?
Then the solid model right about 3/4 of the way through the head layers stuck to the bottom of the VAT so it has a part of the head that is concave. This tells me it has too long of a exposure time since it is burning onto the VAT floor.

Can anyone confirm that is what might be happening or am I thinking about this wrong?


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Re: FTD resin exposure times findings/help :)

Postby 3dprinter.org.ua » Thu Aug 21, 2014 10:35 am

Good afternoon.
Please tell me the optimal exposure time for DLP 3D printer.
I test FuntoDo SB. Lamp 3000 lumens
https://3DPrinter.ua - 3DPrinter shop

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Re: FTD resin exposure times findings/help :)

Postby sam » Sun Aug 24, 2014 1:19 pm

I have the same problem.

05 sec.jpg
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and 0,3sec
03 sec.jpg
03 sec.jpg (18.49 KiB) Viewed 3869 times

I think, there are not enough pigments.

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Re: FTD resin exposure times findings/help :)

Postby adambx » Mon Aug 25, 2014 12:15 pm

i had exactly the same problem. What kind of VAT do you have? Acrylic? Boro?

Adding pigment solved it all. The downside of lots of pigment is that if you have a simple tilt VAT and expose a surface a lot of times, the pigment concentration at that point starts to go down during the build and it gets overexposed. I can't print solid/thick objects for more than 30mm, the vat simply can't do it. You have to play with hollowing out the model in that case.

Is it possible that lower wavelength light penetrates the resin deeper? Since borosilicate (what i have) is transparent to all UV there might be problems with that. Acrylic starts transmitting light at around 380 or 390nm from what i know, so maybe the lower energy light can't penetrate that far.

All the commercial/hobby machines seem to use ccrylic, and i have seen fairly transparent models with really good detail.