Is it possible to use a 3d resin printer to print the pieces required? Or is it required to use a filament based 3d printer?
It’s certainly possible, but there are several things to bear in mind.
First, resins tend to be more brittle than FDM filaments. Some are quite weak as well. You’ll want to look into which resins are stronger.
Second, resins tend to have low temperature tolerance. They don’t melt, but they do lose structural integrity. You’ll also want to look into resins that have a high HDT value, so that hot servos don’t destroy the parts they are connected to.
Third, screwing directly into resins typically doesn’t work that well. You’ll want to use models that have spaces for hex nuts where possible, and where not, modify the holes to fit heat-set inserts secured with a good glue. You can also model the threads into the hole and print them, which will work better than either tapping a hole or self-tapping with a screw.
The parts I’d be worrying about the most would be the arms holding the receiver. Making them somewhat thicker would be a good idea, especially at the ends where the metal eyelets are secured.
Awesome reponse thanks for the quick answer. So resin definitely doesnt sound the way to fo guess its the perfect excuse for me to get a fdm printer than lol. That being said what type of fdm filaments are recommended for this type of build?
My advice is based on having built a lot of OSR2+s and done a lot of research on different materials and filament types.
For the type of motion that the device performs, having the stiffest material was my primary consideration. I didn’t want any part of the unit to flex, as that would translate into “dishonesty” between the script and the actual movement.
Few material misconceptions:
A LOT of people don’t realize that PLA is actually one of the stiffest materials that can be used in FDM.
Additionally, carbon fiber additives to any filament (in FDM) actually doesn’t contribute greatly to stiffness, and actually performs worse than “pure” materials as it reduces adhesion. Carbon fiber additive filaments are generally for aesthetics, helping to hide layer lines which can be combated by shorter layer heights and different print settings.
PETG is often times seen as “stronger” than PLA, but in reality, it is more flexible, but not stiffer. This results in it being more impact resistant (I hope you’re not hitting your SR6 with a bat), and better suited for parts that need to bend (like the locking latch of the twist mechanism).
ABS creates fumes when printing, so unless you’re going through an activated charcoal exhaust, or have your printer in a garage or outdoors, that is not an option.
PLAs is the best BUT:
PLA has one of the lowest melting points of filaments. This is of zero concern for parts like the arms, receivers, etc. as those are nowhere near a heat source. However, if you are running servos that are hot, or go for long marathon sessions, you MAY see some issues with PLA in the main chassis (where the servos live). This isn’t as much of a problem in an OSR2, which has just 2 servos that can get heatsinks, but in a SR6, there is much less room in the chassis.
My recommendation:
Use PLA or PLA+ for your SR6 with an active cooling fan for the servos. I believe there are some SR6 designs that accommodate addition of a fan. This will get you the benefit of the stiffest/easiest material, while not having to worry about melting/warping.
Alternatively, you can use PLA for all parts except for the main chassis and lid, and use PETG for those.
Also, use a lot of infill and walls for your print. This will make parts much stronger. I personally use 4 walls, 4 layers top and bottom, and 100% inflll for any parts besides the receiver. This is total overkill and you can probably get same performing parts using 4/4 + 40% infill, but I like the weight and feel it gives to parts.
LMK if you have any other questions, happy to help.
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I appreciate all the advice. Im new to these forums and i must say the people here give some seriously awesome and verty detaoled advice.
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I prefer PETG over PLA because it will bend instead of break. PLA is a bit stronger, but also much, much stiffer, making it more brittle.
PETG also has a higher temperature tolerance, though in the past, I had my servo mount area deform with a PETG base because they weren’t being cooled enough and I was using a lot of fast scripts. I’ve redesigned my base to cool much better, and now also print it in polycarbonate for the highest temperature tolerance. But all the rest of the parts I print in PETG. I did try all-PC once, but the arms broke a couple times, due to how brittle it is.
Cooling the SR6 is something I haven’t looked into, as I decided it’s just not for me. I get the impression that most people using an SR6 don’t use it for very fast movements, so cooling may not be a real issue. But if you can find a design with active cooling for the servos, I’d definitely use that instead. You can also always reprint the parts with a different material, so there’s no harm starting with the cheapest option (PLA), then replacing parts later if you notice problems like deformation or cracking. That’s the benefit of having your own printer.