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Experimentation

PostPosted: Tue Jul 21, 2015 2:58 pm
by bubblenuggets
Has anyone done any experimentation with LED current and Exposure times? I'd love to be able to cut the exposure time by 5-10 seconds to save 30-60 minutes on a 300 layer print.

Additionally, the x-y resolution is listed as 313 µm or 328 µm depending on source, which equates to a 128 x 64 LCD. Has anyone looked into other LCDs to increase pixels-per-inch and reduce x-y resolution? Is it even feasible to cure something like 78 µm x 78 µm sections? That would be a 512 x 256 pixel array (still 40 x 20 mm). Is there a minimum x-y resolution that is realistic given the curing process?

Finally, has anyone experimented in post-print polishing (e.g. acetone vapor bath for ABS)?

Re: Experimentation

PostPosted: Fri Aug 14, 2015 9:20 am
by TieBox
Sorry for the wait!! We have done some experimentation with a linear relationship previously but it was not very accurate. Harsha is working on an accurate UV output curve now actually. You could decrease time by increasing current but this often results in excess resin curing around your model and hurting your resolution. Many of our best resolution prints have been done at the lowest current setting of 5.5ma and a long exposure time. We'll let you know as soon as Harsha has finished his experiment.

A lot of research went into our LCD screens and we had a hard time finding any black and white screens with higher resolution. I assume they are hard to find because these screens are usually used on calculators and other devises where fine resolution is unnecessary.

In theory you can print as small as your pixel. The curing process occurs on the molecular level so the theoretical minimum is on that same level. Even if you are using a laser to cure resin you will be limited by your ability to focus light before you are limited by the resin's curing ability.

I have not done any chemical post processing tests yet. Since are models are so small I feel that you would loose a lot of detain polishing this way. I'll give it a shot though and let you know!

Re: Experimentation

PostPosted: Sat Aug 22, 2015 6:35 pm
by bubblenuggets
Thanks for the follow up.

I've tried the recommended water rinse as well as 3-15 minutes of UV curing but I still can't get rid of the excess resin smell -or- every last bit of excess liquid resin. This was on a Statue of Liberty print, so lots of tiny spaces. Any suggestions? I can't very well print things that will be handled a lot (miniatures, jewelry, etc) if it will stink up a room and leave resin traces on people's hands...

Re: Experimentation

PostPosted: Sat Aug 22, 2015 8:03 pm
by ron.kundla
An isopropyl alcohol bath will remove the excess resin. The alcohol is a solvent to the resin. I put my models in a beaker with enough isopropyl alcohol to cover the model and submerge for 2 minutes with occasional agitation and swirling. Remove from the alcohol and pat dry or use compressed air to help evaporate the residue.

Some people have used an ultrasonic machine to help get rid of resin in small spaces. I've heard using water with soap and also putting the part in a sealed baggie with isopropyl alcohol, then putting that in the water of the ultrasonic works.

The smell is harder to deal with. Different resins have different chemicals that may alter the odor. Using the isopropyl alcohol helps alot, but UV curing the exterior will help as well.