lets be honest about resin 3d printed parts

[tbavcevic]

not sure if this theme is off topic here but anyways sorry.. this is not rant it is more something like sharing of what i think about all this after wasting few liters of resin.

since this summer i have been playing with resin printer, i have no experience with normal 3d printers so what i say here is only about resin printers...

everyone doing electronics nowdays can make some realy nice and cheap pcb-s in china,but most of us have problems with cases for same pcb-s. either too expensive or diy route too ugly. to try to avoid that problem i bought resin 3d printer since everything i read on internet states how good how high resolution resin printers have how durable parts are bla bla usual marketing stuff.

have tried few different resins, one basic one expensive and one realy cheap and transparent.

first there is many problems with resin specific settings that manufacturers of resins dont realy go in detail(or no info at all for some) about so you are left alone to experiment with most settings. then there are room temperature that also seem to affect resin a lot and sometimes in weird ways.

then there is zeroing out process which on anycubic photon s is realy simple, but tedious and should be automatic and some form of overcurent monitor should be implemented on motor so that it will stop itself from destroying itself even if it gets command to go too far into screen... also touch screen is rubbish so it misclicks most of the time what can also result in braking of only expensive part in this printer, screen.

now there is resin vat, with flexible plastic that is pita to replace as you need to waste a lot of time doing that, and it is easily scratched or burned(?) by bottom layer long exposure.

now resin handling is absolute nightmare, thing is toxic for start and you realy need good air ventilation not possible in all workshops as it needs to be designed specificaly to vent fumes out, no ammount of filtering will help. resin is somewhat thick fluid like car oil but it is even more sticky and hard to wash out even with IPA but that depends on resin manufacturer/type. all resins i have tried had issues with leakage from cap seal on bottle, few even drip massively when bottle is shaken and you do need to shake it realy well to point where there are many bubbles in it what is another problem as then you need to wait for bubbles to dissipate when you pour it in vat so you do not have holes in first layers.

now software, 3d modeling software is complicated and i am using only tinkercad as i need only basic stuff so cant comment on that. slicers like chitubox or chitubox clone that is shipped with photon s are somewhat limited in options but work well most of time.

now about actual printing, failure rate even with dialed in settings is too much, one could say that settings are not dialed in then, but if it works for a whole week with various parts, and then one day without touching anything it either wont stick well to platform or it breaks in half or something similar and then next day it works again with same models and everything, same temperature, humidity, everything... it is just unreliable.

now printing with supports or models made specifialy to stick direct on platform, i had better results with direct platform just need to watch so surface area of any layer after base layer is not larger than base layer, that can be easy to achieve. printing with supports and auto generating supports is in most cases just bad on multiple levels, first level is supports auto added by chitubox are everywhere and you get better results manualy placing supports, second level is you can never get 100% of print quality where supports are connected to model or if you go too far and make them thinner they break and finding sweet spot where it does not ruin model so you need to sand it too much and that it does not break is almost impossible.

sanding is somewhat easy but only on straight parts, where there is some rounding its hard to sand it so it is not too visible.

ipa bath is all fun but with some resins i have left them for few hours and parts would still be sticky, but some resins may need different cleaner i am not sure about that...
uv curing is interesting and sometimes if over exposed it leaves white residue on some parts...

from all parts i have printed most have broken apart after some time of use, it seems that resin while good for high resolution prints it is not good for thin parts, and even some thick parts have snapped in half with not too much force. some resins are somewhat bendable, but this is not guaranteed! you bend it 100 times a bit and it does not snap, but next day you look at it and it breaks like glass! also if temperature where parts are used is below 20 degrees everything will break if you touch it.

i could go on for days so i will stop now, my conclusion is that while this technology is relatively cheap and useful, it actualy ends up being more expensive and useless if you want to print anything other than d&d figures or baby yoda with it.  sh.. stuff made with it is good and it works and is high precision, but it does not last long enough and is not sturdy enough and not reliable if you actualy use parts. so for everyone that do actualy want to make parts for use not just to put them on blog or on some site just to show off is useless. if anyone have any alternative way of manufacturing small custom parts somewhat cheap please do say how. or say how you make parts that are usable with this tech.... sorry for engrish and sorry for long post...

[Alex Eisenhut]

I always look for ready-made cases before starting a project. Much less pain that way. There's decades of experience and design in the commercial products.

I don't quite understand this trend of making the PCB first, then realizing it needs a case after ...

[donotdespisethesnake]

Not sure why you went for a resin printer, regular FDM printer with PLA or PETG would be better for this.

Printed parts will never be as good as commercial injection molding, but if you do want to print a customised box it is relatively easy - but you will need to be familiar with 3d CAD software, or just print other people's designs. Also bear in mind that commercial boxes use flame-retardant plastic. AFAIK, all DIY type 3d printer use polymers that are not flame retardant.

I've designed some boxes with OpenSCAD, printed in PETG on Prusa Mini. They are good enough for hobby use, mainly for small projects. For larger projects it's just quicker/simpler (and probably works out cheaper) to buy commercial boxes.

[Ian.M]

Its quite simple: extrusion strengthens most plastics by sheer in the flow aligning and partially straightening their long chain molecules.  See https://www.ptonline.com/articles/extrusion-orientation-the-good-and-the-bad

Unfortunately FDM printed parts cant take full advantage of the oriented strength because the deposition process and nozzle design prevents the use of Z oriented filaments.  Add the problem of depositing hot on cold, with resulting poor fusion and its not surprising that FDM printed objects tend to suffer from layer delamination under stress.

Anyone who's done fiberglass work or worked with epoxy/wood composites will tell you that polymerized resins without reinforcement tend to be mechanically weak - either brittle or easy to tear.  Unfortunately, AFAIK there is no way to directly add reinforcement fibers in the bulk of a 3D resin printed object.   You *could* use the resin printer to create a mold, spray it with mold release, pack it with reinforcing fibers, then vacuum infuse it with catalyzed resin.

[tbavcevic]

yes it seems that fdm printer would be better option for boxes, but i went with resin as there are multiple "small" parts that i end up needing for various stuff like pictured m42 to sony e mount adapter, and m42 thread made by resin printer actualy fits ok on few of my m42 lens, if only there is resin that is not brittle on low temperatures as most of time i need m42 adapter is on my huge mirrorred lens(large enough that camera gets mounted on lens instead of other way around) that i use at night for astro photos. first adapter i made few months ago that i used extensively worked realy nice up until outside temperatures dropped, but on first "cold" use it just broke without any force.

im curious would molding parts preserve high resolution needed for thread? also is there easy way to make metal parts from same mold?

is comercial injection molding available for prototype use like few parts? if cheap enough then 3d printer could be used just to check if all dimensions of part are correct and after fixing errors order injected part, that would also be good solution..

[xrunner]

not sure if this theme is off topic here ...

There is a 3D printing forum board here -

https://www.eevblog.com/forum/3d-printing/

[Ian.M]

You can certainly get the detail if you wet out the mold surfaces with catalyzed resin, + colloidal silica to make it thixotropic before packing it with the reinforcement fibre.  For a strong female thread, I'd suggest dusting the wetted out core with fine chopped fibres then winding tow (continuous fibres) into its threads to get a random strand surface over reinforcement oriented with the thread.

The new problem is how to design a close tolerance multi-part mold you can actually get the part out of! The threaded core would be particularly problematic, and I believe you'd need a rather complex multi-part one over a tapered mandrel so it could be removed in sections. . .

[KaneTW]

I use both FDM and SLA extensively. Each have their uses. Failure rate with a Form 3 is pretty low, and I've never had a failure due to the printer itself, only part design (e.g. too many supports and you can't get them off, or a cavity that isn't washable and remains sticky).

FDM for wider material selection, structural parts, things that have a well defined base. SLA for watertight parts, high-resolution stuff, things that need supports anyway.

Rest is just experience and knowing how to approach specific problems. SLA threads will have a touch too much material, so you can chase them with a tap/die or reduce it in software. Using the right resin for the right application is also important. If you want to machine resin, using standard brittle resin will lead to disappointment.

[Bassman59]

I always look for ready-made cases before starting a project. Much less pain that way. There's decades of experience and design in the commercial products.

I don't quite understand this trend of making the PCB first, then realizing it needs a case after ...

I simply don't have the tools to machine a metal case, even if I buy an off-the-shelf Hammond. I've tried with a drill press, a nibbler, even the mill at the office. I kinda suck at it!

So what I do is prototype a case with my 3D printer, with the intent of putting it in that Hammond box. Various places offer simple front panels that they'll make from your DXF.

I import the board STEP model into Fusion360, bring in a Hammond box model, make the board fit, and then work out where the holes in the panel must be.

Oh, yeah, I think Protocase Designer might be a good option too. Their most recent updates include letting you select the enclosure type and specify some sizes, then they'll give you the STEP model that corresponds, and then you being the board and the model in Fusion and place the holes. I haven't gotten any quotes. I expect it to be kinda expensive. I'll report back when I get numbers.