Did I just find an ABS-like resin?


#1

You’ll know from previous posts that I’ve been searching (and pleading!) for a resin that has the qualities of ABS. Something aimed at end-use manufacturing. This segment is growing fast in SLS and FDM but somehow totally neglected in SLA. The qualities that I need are:

  1. High rigidity and tensile strength (similar to ABS)
  2. Not brittle (which eliminates just about all Formlabs resins except durable and flexible)
  3. Heat resistant to at least 70C (which eliminates durable and tough)

I’ve been experimenting over the last year by mixing all sorts of Formlabs resins, sometimes with interesting results. For instance I found if I added 40% Tough to Grey Pro then suddenly I stopped getting failed prints and the parts are stronger. However they are still brittle so wasn’t the answer.

I recently ended up with a mixture that gets pretty close to my requirements. It’s 40% Rigid and 60% Durable, printed with Rigid settings. I just call it R&D. I cure it at 60C for 60 minutes but haven’t seen any difference when I tried other settings. The result is a strong part, very similar to ABS, without the low HDT of Durable and without the brittleness of all the other resins. It’s by no means indestructible and still retains some brittleness but practical enough to make “real stuff” out of. It’s now my go-to resin for just about everything. We recently printed some non-structural parts for a racing car and despite the extreme heat cycles and sudden splashes of cold water, and being man-handled between races, the part held up beautifully. The aim was to test heat resistance and sudden temperature changes over a few days. The parts worked well.
It will be great if some of you guys can try this mix and share your findings. If it works maybe we can convince @Formlabs to make this available as their first real “additive manufacturing” material!

Of course the ideal will be heat resistance over 100C as with ABS so maybe I’ll do a similar experiment with the new High Temp resin and Durable. Not sure how rigid High Temp is though.

I include some of those who participated in previous discussions on this topic:
@jarmatis @CraigBroady @rkagerer @themedulla @wunwinglow @mrwakefield @Rob_Steinberg @digby @JohnHue


#2

Nice! Thanks for tagging me - I love hearing about the results of resin alchemy.

I played with High Temp; I got the impression it’s one of the most brittle resins Formlabs offers. That makes sense as I imagine it was designed for molds, where you would want to maximize dimensional stability.

But there might be hope - I found the brittleness was reduced significantly when I mixed it with a third-party additive (flame retardant FP-600).

I was about to offer to send you the rest of my HT cartridge but when I checked I realized I already mixed all of it.

On a different note, if anyone else tagged here is going to this year’s user conference, maybe we can meet up for a little “resin alchemy” splinter session.


#3

What is the dimensional accuracy with this mix ? Given the huge difference in mechanical properties between Rigid and Durable, are the parts still as precise at they are with a 100% Rigid print ?

This is very interesting indeed, I would love to see some example of the parts made with this “R&D” resin :wink:


#4

Patronus, thanks indeed for this effort. I will definitely be giving this a go. I will certainly get back with my findings.

As you know, I had/have real problems with Black v4, and recently tried a 50/50 mix of Clear and Black v4, run as Black, and that worked really well, although I haven’t assessed its strength yet, I was just happy that it cured and I can use the resin!!

Onwards!


#5

@JohnHue I haven’t specifically tested the dimensional accuracy of R&D but all my prints so far fitted perfectly where they were supposed to fit and fine details were crisp and I had no warping. I’ve also had no issues spray painting it.
It’s probably worth doing a test print in both materials and comparing them in detail (for someone with spare time and material!)


#6

A little off topic but I actually keep a bottle of mixed leftover resins, whatever they may be, that I use for prototyping. The last batch was some black, some grey, some tough, that I poured into an almost empty bottle of white and gave the bottle a good shake to mix them all up… The result is a grey print which, using white settings, comes out perfectly. Probably breaking all the rules but works like a charm.


#7

Like the Dum Dum “mystery flavor”. Sounds like fun.
Do you keep track of your inputs in case you stumble on something good?


#8

@sigmazero I can’t say that I keep track of what I pour into the leftovers bottle but it’s mostly a combination of black, white, grey and tiny amounts of whatever else I could scrape out of used resin trays. Somehow it always ends up being some variety of light grey - and always prints like a dream!


#9

@Patronus…Hi… I’m asking if you can elaborate on how you went about printing with the ABS like resin you mentioned…40% Rigid-60% Durable.
Doesn’t sound like you needed to run the machine in open mode, correct?
Did you create a mixture with the above mentioned percentages, put that mixture in an empty Formlabs resin container (of some sort) and use that container in the machine? I know you said in the post you ran the resin mix as Rigid… but did you put your mixture in an empty Rigid container?

Any other further insights on how you went about this would be great. Sounds very interesting.

Thanks again for the help.


#10

@jfishman correct, to use the R&D mixture I’m not running the machine in open mode. I prepare the mixture in a separate container and then pour it back into the Rigid cartridge. I then print it as Rigid.
You have to mix the Rigid and Durable very thoroughly which is easier said than done. It takes a good minute or two of vigorous stirring before the mixture is uniform.


#11

Thanks very much for the further explanation!
I appreciate it!!


#12

Hi, I don’t know if it wold help, but when I get parts made up for work the print center uses a resin called…

Accura ABS Black (SL 7820)


#13

@TC61 thanks, it looks really interesting. I like the fact that you can get it in black. Only downside appears to be a low HDT and GTT compared to real ABS. My parts often see 60C which of course is no problem for ABS but apparently pushing the limits of any non-brittle SLA resin.
I don’t see the stuff for sale anywhere though, I wonder what it costs? I’d like to give it a try.

Anyone else here using it?


#14

I have ordered parts in Accura from 3DSystems directly. It is nothing like ABS, as you noted with the difference in HDT and GT point but also tensile and flexural modulus. I haven’t tested it but if I had to guess I’d say it’s close to Grey Pro from Formlabs, and certainly much less flexible than Tough which, post-cured, is in my opinion more like ABS than all the resin I just wrote about.

In the description 3Dsystems also says Accura is used to replace PP or ABS parts, which just goes to show how loosely they use these comparison given how different these two plastics are.