I’ve printed probably 5 kilos worth of prints with a lot of success, but exclusively PLA. I’d like to branch out to a new material. Should I start with ABS or TPU?
I’ve printed probably 5 kilos worth of prints with a lot of success, but exclusively PLA. I’d like to branch out to a new material. Should I start with ABS or TPU?
Thanks. The main thing with paint is to be absolutely obsessive about the prep details and sanding. I’ve trained two apprentices. The hardest thing to defeat is one’s internal expectations of time. It is only right and ready when it is perfect even when redoing that primer for the fifth time feels like murder and the issue is only the size of a dime, it simply does not matter. That dime will cost two days to fix when it shows through, and that knowledge must come first. I told everyone that ever worked for me, “sand it until you think you are done, then take a break, come back, and acknowledge you are finally halfway done. Then repeat this until I cannot find a single issue with the panel.”
The cool thing about ABS and ASA is that you can sand it to a polish. Just treat it like a metal polish job but use automotive polishes instead of rouge like for metals. There are usually no inclusions from the print lines in my tests and it polishes to a remarkable finish that looks like extra shiny Lego’s. In fact, if you take a fully polished part and break it, you will likely find that the surface is changed for nearly a millimeter down. It happens even when the polish is done meticulously by hand with no buffer to heat up the surface. I’m not entirely sure what is happening with that one, but based on how it sounds and feels I bet there are better mechanical properties as well.
From my time around automotive racing, polished ABS/ASA feels like parts that are finished to reduce stress risers like how pistons and rods feel different after a similar polishing operation. I haven’t tested it, but that is how the parts felt to me. That might be one to try out, even with mechanical and functional prints. If you happen to snag some sandpapers, it only takes a sheet of 600 or 800, as a baseline where this has removed absolutely everything below regardless of what was below, then use 1500 to knock this down. Finally, toothpaste can nearly replace an automotive compound. No joke I have used it on cars in a pinch with a heavy cut pad. For a mirror it will take an intermediate cutting stage before the final polish. For something like a print that is already sitting at 1500 grit, toothpaste will get more shine than a typical new Lego. Just use an old sock and let the compound do the work just like with a buffer and pad.
The little Proxxon pen sander is also a must have device for print sanding in general. It is worth the spend. You only really need the sander without the power supply though. The supply is the scam. Just clip the wire and add a DC barrel jack to any old 12v 1A wall wart. Their sandpaper is really high quality and worth it, but some decent double sided tape will work to make your own. You can also make your own sandpaper holders to get into awkward places.
I don’t know that I could actually finish a Voron build now. That is the real underlying truth of it. I am physically declining and my up time is very limited over the last coupe of years. That has kinda quashed my EDA and circuit etching projects too, sadly. Even my riding is suffering. I did 26m every day for ~8 years after the broken neck and back, but now 16m every 2-3 days is all I can do and still sleep 4-6 hours at most. It is what it is… “Ya get what ya get and ya don’t pitch a fit.”
Thanks for taking the time to type out that reply, it packed a ton of information. I think you’re under selling the eye and the technique necessary to sand well. I’ve done some DIY auto-body and paint work and I really struggled to know when I had sanded well enough. Yeah, I knew I needed to sand more, but I had no idea where to focus my efforts and couldn’t easily distinguish a high spot that needed to get knocked down vs low spot that needed to get filled. Building that skill to the point of it being intuitive seems like something that would take a decent amount of practice or a great coach.
I hadn’t considered polishing ASA. I’m somewhat tempted to give it a go. The hardest thing for me would be figuring out how to sand large curved surface in such a way that doesn’t result in lots of obvious flat spots. I can absolutely see sanding/polishing making prints a bit stronger.
I’m sorry to hear about your physical condition and wish you as much additional recovery as possible. I totally get having very limited time with two younger kids in my house. I think all in the build took 4-5 months starting from printing parts, ordering a kit, and finishing assembly. Even though my kids are not new to me anymore, I don’t know that I’ve fully come to grips with the fact that I can’t complete projects as quickly as I once could and I should probably slow down my rate of project accumulation.
The real touch of a painter that is hard to acquire is only really relevant in the last layers of primer and sealer. It is possible to feel things that cannot be seen using fingertips over a panel. One of the aspects of this is simply part of the job. You’ll wet sand so much as a painter that the skin on the fingertips is very thin. I worked until my fingers bled most days. That thin skin is always hot and super sensitive. It is possible to learn to barely graze the surface and feel the tiniest imperfections.
The main trick to calibrate touch is Wax and Grease Remover (a solvent). When W&GR is used on a panel it will briefly form a wet gloss. That wet gloss will simulate what the clear coat will look like but slightly worse because a 2k clear is much thicker and will level.
When sanding anything from fillers to high build primers, guide coats and sanding blocks are what matters. Blocks must be wide enough and shaped to bridge the issue. With most regular jobs that don’t require absolute perfection, curved surfaces are sanded by hand using a soft foam block.
Back in the day, I would have loved 3d printing and TPU because I could have made custom sanding blocks for jobs. Back then I used balsa wood to make special shapes when I needed them. I had probably three dozen or so sanding blocks for all the different issues I came across.
For guide coats, some people like a graphite like powder that is made for guide coats because rattle can enamel is absolute garbage paint and leaving any of it behind is a major risk under urethane paints especially the color coat. However, I still only ever used whatever junk rattle can I found on sale for a dollar. You only need a light speckled but consistent dusting of a guide coat. The sanding block will show the highs and lows. Just be sure you’re using the block like a rolling pin and not like a scrubbing brush. You can even use a guide coat with sanding prep for polishing work.
There is not a ton of skill in this area. A few tips about techniques is all it takes. The real skills of automotive paint are in tinting colors to match the degradation of an existing finish, matching orange peal, and primarily knowing how to best remedy situations when things go very wrong. All the various ways paint can react badly are complex problems and those lessons are hard won with bad experiences. Most can be avoided with meticulous cleanliness at the earliest phase of work.
I don’t do well with very long project timelines. I think it is quite remarkable that you can last for 5 months on a project with kids and all the distractions that entails. Sleep deprivation puts me in situations where it is like my mind is wiped every couple of months. I just don’t care to get back into a complex project and lose my motivation to some new curiosity. I tried to fight it at first. I was only like this after disability. It just becomes a depressing spiral and I don’t tend to finish very much. Hopefully that changes. I have several nearly completed projects I would like to finish, but oh well. Kids would absolutely drive me nuts, but I am at pain levels with sound and some light sensitivity 24/7.