3D Mini Printing Process Walkthrough (Elegoo Mars 3 + Chitubox)

A while ago, I made this 3D Printing Process walkthrough video, which I thought I would share to herald the renaissance of this blog after a few years lying fallow.

Note: if all goes according to plan this should be the first post to this here blog that finds its way to The Gaming Tavern, for which I am indebted to Tom, the Guvnor.

I made the video with more than a little assistance from my daughter Alice, on filming, editing and production.  My purpose was twofold:

1. As a helpful guide to others starting out on 3D printing
2. So that friends thinking I'm now a source of endless cheap minis are aware of the overheads

In it, I talk through setting up a print job on the Elegoo Mars using Chitubox slicing software, highlighting some of the pitfalls to watch out for and how to avoid failing a save against them.

Made in my basement Underdark Man-Cave which I should point out is much less tidy than the areas I share with the rest of my family up in the sunlit realms!  What can I say - it's functional.  

Here is the link to the video in case the embedded video doesn't come through on RSS feeds:

https://drive.google.com/file/d/1CxKQ3fjfvmQIHRDbCRg7k3iXLwrZvtPh/view?usp=drive_link

(Health and Safety Note: the boiler in the background where I am using the power hose, with the exposed electrics, is disconnected)

Background music is by my friend Dave Diliway and his bandmate Nick Langley, of Cosmonauttransfer, used with permission.

https://cosmonauttransfer.bandcamp.com/music

I am going to add some comments - because I know this is something that divides opinion - on the final part of the process I show in the video in which I leave my prints to cure in the sunshine, in a conservatory, rather than using a UV curing station.  Here comes the science part - skip the next three paras to get to the tl;dr.

Glass filters some wavelengths of UV but does not block them entirely.  The distribution of UV extinction will vary dependent on the type of glass and whether a UV protective film or coating has been applied.  The ordinary built-environment glass used in the study I've linked here transmitted 74.3% of UVA; that will be 55% for a double-glazed layer (while all glass types fully blocked the more harmful UVB radiation).  The upper wavelength limit of the UVA range of the spectrum is 400nm, then you're into the longer-wavelength "visible" spectrum.  This is going by the technical definition of "visible spectrum" because actually, the human eye can often perceive wavelengths as short as 380nm, or in some rare cases even shorter - yes, you can actually see part of the UVA spectral band. 

There's a nice accessible piece on UV light bands here:

https://solar-center.stanford.edu/about/uvlight.html

Now the resin I am using is fast-curing photopolymer with an optimal curing wavelength of 405nm.  Yes - really, this isn't even ultraviolet!  You can see light of this wavelength.  (You might even hear "Smoke On The Water" playing in the background when doing so...).  And really, this 405nm specification refers to the LED output wavelength you should be using to cure the resin.  But LED's are only nearly monochromatic - they aren't lasers, and an inexpensive 405nm LED will actually generate ~ 95% of its output over a range something like 395 - 415 nm.  Some of this is in the UVA and some in the (technical) visible range.  Plenty of that is likely to be good for curing our 405nm resin - but so too will plenty of the sunshine coming through the conservatory window, which will also include this range of wavelengths (even if it's down to 55% of original strength in the UVA bit of the spectrum - you'll get more variation than that depending on time of year or cloud cover).

I am leaving my prints out in summer sunshine for a minimum of 1 week (I don't get time to do this outside of summer).  I visit them fairly frequently during that time to rotate them so they receive an even distribution of UV.  A model that has not been completely cured will suffer gradual shrinkage and this may spoil any paint job, however models I produced over two years ago are so far still looking good.  I'm willing to bet they'll remain so.

TL;DR: if you're using water-washable fast-cure photopolymer resin, with a curing wavelength of 405nm, and you have somewhere with plentiful sunshine where you can leave your prints for a week, remembering to turn them 1-2 times daily, you should be safe to use the method I've outlined in the video.  If you're doing this in the winter, or in a hurry, or using resin that isn't water-washable or that cures at shorter wavelengths - you should probably invest in a washing & curing station.