Stronger resin option

I am sure you guys are constantly thinking about new resins, but I wanted to throw in my needs and opinions.

I am using the Form 2 for prototypes for research and development of a medical device. It would be nice to have an option of a stronger material that could be more functional. Tough is working OK, but there are limitations.

Carbon3D offers an epoxy-based resin that is roughly twice as strong as Tough. It is ridiculously expensive as well (Carbon3D’s pricing model is generally pretty heavy) at around $400 for 750mL and it is a two-part resin (probably not technically executable on the Form 2. So probably not easy to just directly transfer over.

At any rate, my input is that I would gladly pay $400 to $750 for a 1L resin that had twice the strength of tough if it were an option. I don’t know how many others are in my position, but the cost is easily justified. I spend several thousand a month on machined parts and any that can be printed clearly justify the increased resin cost.

I have heard of some medical resins from compenies detax or nexdent. not sure if it is as strong as Carbon3D

When you say “stronger” which property are you looking for? See the table for a comparison of their stronger/stiffer materials. Their data for the Dental SG resin is pretty poor but I would say it is similar to High Temp at room temperature. I do med device engineering and use Clear/Grey almost exclusively for fixturing and first gen component prototypes. The Tough material is not stronger by any specification, it is simply more impact resistant. Tough also has pretty poor accuracy and feature detail compared to Clear, it is just too gummy for stuff I do. The High Temp is the stiffest of the resins (but most brittle) so it might be a good candidate for fixturing also, I am just happy to stick with their Standard resins though for the most part.

I will second your motion though, I would pay more for resins that can replace Aluminum! One of the recent parts I made would be machined for $181 out of aluminum, instead I printed it out of Grey for $3.40 worth of resin. So even if the resin costs 50X as much as Standard resins ($7,450 per liter!!), it still saves me money compared to machined Aluminum. That doesn’t even factor in lead time costs.

The last bit that i just remembered is that you can plate printed parts with copper and nickel to get drastic increases in strength and stiffness. It can be pretty cost effective if you do medium to large batches and you intend on keeping the parts in service for a while. Repliform and SAT Plating are two that I have used.

I am referring to the ultimate tensile strength. The Epoxy resin from Carbon3D has an ultimate tensile strength of 88Mpa - that’s almost twice as much as Tough. The accuracy and surface finish are pretty nice as well. The Form 2 is so good on performance and so much lower on cost I can’t justify a Carbon printer (they are subscription model at something like $50k a year), but it would be nice to have higher performance resins even if the cost is much higher.

The standard resins for the Form 2 are good, but I need more impact resistance for my prototypes so I am mostly stuck with Tough. It is a bit gummy but I have been pretty happy with it.

Thanks for the heads up on the plating option. I might see if I can find a place close by where I can finagle a quick turnaround. Lead time is probably more important than cost at the moment.

Carbon’s materials are definitely impressive when it comes to mechanical properties. Their pricing model is not impressive. There are some service bureaus doing Carbon parts if you haven’t looked in to that yet.

Try “Durable”. I’ve just started printing with this, having exhausted the capabilities of Tough (it’s too brittle). I have printed some parts but have not evaluated them yet. But I like the way they feel. And they don’t appear to be “creeping”, which is what I was worried about, because Durable is more flexible than Tough.

Tough V4 is supposed to have fixed this creep issue, but the Tough V3 I’ve been using doesn’t always hold its shape (though it’s a lot better than V2 was).

I’ve got some Durable and use it somewhat - it is great for simulating polypropylene. Unfortunately it is about half the strength and rigidity of tough. I’m really hoping for something stronger (and if it could be less tacky that would be a huge upside).

I suppose I could try and get hold of some of Carbon’s epoxy resin and give it a shot in open mode. I’d much rather hand my money to Formlabs and not give up the heating and auto-dispensing capabilities.

It might also be interesting to see if some glass beads would be too problematic (settling, incomplete curing, etc). Adding that to Tough or Durable might be impressive. I’m assuming Formlabs has played around with this and there is a reason it’s not an option.

Hey guys, I have had some luck mixing clear and tough for a stiffer yet still impact resistant part. It also makes the post cured part less gummy than straight tough. I’m using 1/3 clear and 2/3 tough. The color is decent as well. I’m sending parts out to repliform for copper/nickel plating so hopefully that’ll get me to where I need to be. With the heavier nickel coating and straight tough resin they are claiming 1/2 the strength of aluminum, which is pretty decent since you can (potentially) thicken up a part to get it close enough. They have a generous new customer deal as well.

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Thanks for the tip.

Out of curiosity are you using the printer in open mode or mixing in the tough resin container and setting Preform on Tough (or Clear?)?

I’m printing with clear settings, I figured that the clear supports were more brittle than the tough supports, so the (tiny) bit of logic was that the support density would be more than adequate on the plain clear settings. the mix was still tough enough for me, IE I can bounce it off the floor pretty hard without it cracking. The tough could also do that, however the clear was obv nowhere close. Tough is good, just not stiff enough, so the additional clear resin fixed that up for me.

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Thanks - are you post curing?

Thank your for the testing and reports regarding Tough + clear, very useful ! Please do post here is there is any downsides (during printing or use) with this mix.

Yes I’m post curing, I have a heated blanket + nail salon UV on top of a foil lined box setup, so far I’ve been happy enough with that. The only drawback to the mixture right now is that I’ve got to manually mix it with a gram scale. The properties seem to be what one would expect with the mix ratio, the color is more transparent than the usual blue. I do find my parts don’t have as much residual layer as with just Tough, but not quite as clean as pure clear. Materials seem to be combining in a linear fashion, but really someone would have to do a full suite of mechanical testing to actually confirm this.

Thanks for the testing!
How brittle have your prints been? Any issues with the parts breaking under bending?

Hey. I’ve not done any quantitative testing at all, however I have ‘tested’ both the tough and the 2/3 tough 1/3 clear by tossing my parts onto a concrete floor over and over. The 100% tough parts were very impact resistant, and I found that the 2/3-1/3 mixture to be able to absorb those same impacts. If you linearly interpolate the material properties you’d see that the % elongation at failure should be around 18% for the mixed resin, compared to 24% for Tough and 6.2% for clear.

For my parts 18% is still plenty, and the noticeably stiffer part is worth the loss of % elongation. The higher stiffness and flexural modulus + higher tensile strength (assuming linear material properties) was a worthwhile combination. The tough material by itself is VERY tough, but too bendy, so I felt it could stand to be a bit less tough, yet still ‘tough enough’ for me while being noticeably stiffer.

One more point, I’ve only tried printing on Clear V2 settings with 50 micron layer thickness (happened to be the empty cartridge I had on hand).

I am curious if with proper curing can the Tough be made non “gummy” as people have stated in this thread . Or dose Tough always have a slight tackynes?

I have the Curebox by Wicked Engineering that sets the temperature and time of the cure accurately. I have played around with different cure times, water curing, etc. If the part isn’t cleaned extremely well there will be significant tackiness no matter what you do. The water curing definitely seems to help, but only if you have a really clean part.

With optimal cleaning and curing there is still a very slight tackiness that I think is the nature of the material. I have not found increased curing to reduce the tackiness beyond this minimum value. Getting the cleaning and curing right is a real necessity for this material. Once you get it right, the remaining tackiness is pretty acceptable.