Glue big parts

Anybody knows or have experience on how to glue big parts?
I want to use the same HT resin to glue the parts, I will produce separate parts, then I will join them and soak the joint line with fresh resin. Then I will place the big print under UV.
This will work?
Anybody knows or have experience with this idea?

You can definitely attach parts using resin and then curing it with a UV light. The issue though is that the resin doesn’t cure all that fast so if you have to hold it in place that can be a challenge. I use cyanoacrylate glue which can hold strongly and cure fast, it also sands perfectly with the surface of the resin as long as it fills the gap fully.

I have done this many times and as @Zachary_Brackin states it is a challenge because of the speed at which it cures. I’ve seen UV pen lights recommended, but have yet to get one.

What I do is put a few dabs of the same cyanoacrylate glue Zack mentioned just enough to hold the pieces together, fill in the gaps with resin, let cure, then sand down. When finished you cannot tell it has been joined.

Edit: I forgot to mention as, @JohnHue rightly did, I do not have experience with HT resin. I have only used this method with standard resins.

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So I have no experience with the HT resin (just got the printer this week), but I would guess the main issue here is temperature resistance. From the images the resin looks like it’s not totally opaque so curing the assembled parts in a UV oven for a few hours may work, I’d give it a try personally.

Otherwise, common cyanoacrylate such as the Loctite 401 don’t behave well at more than 80-120°C so that wouldn’t be recommended. There are cyanos such as the Loctite 4203 which are supposed to be optimised for heat but IRL they are only marginally better than common cyanos which it… Not all that good. Plus there is the fact that these glues cure with moisture so an absence of air will actually prevent good curing unless you have two really really flush surfaces.

A heat-resistant fast curing bi-component epoxy can easily take the same heat as the hight temp Formlabs and cures under any conditions and can fill gaps. The best choice (EDIT : IMO) if UV resin curing doesn’t work.

There is no more of an effective bond than one created by joining resin with resin. CAs do not produce nearly as strong a glue joint. Epoxy doesn’t do so well either. I’ve tried both.

I print small frames for quadcopters with my printer. I then race & inevitably crash said quadcopters. Provided I get a clean break, I stick 'em back together with some resin and a UV LED. Takes 10-15 seconds and I’m back in the air. I have never had a print bonded back together with resin break in the same place twice.

Thankyou for your comments.
Yes, the problem of cyanoacrylate is that it doesnt resist at HT, but if used only to keep the parts in position and HT resin does the glueing job, it should work.
I am going to launch 4 jobs to build a big part, and before waste material and 50 machine hours, I thought it was better to ask prior to fail.
Only another question… how much should be the clearance of the gap to be glued?I guess not mor than 0.5mm, or more?

Most CA don’t like bigger than 0.1-0.2mm gaps. Epoxy, depending on the type can work with several mm of gap. As for Resin, I guess Randy_Cohen will have more experience.

I would love to hear back from you after you finish the job :wink:

It’s extremely important to get the HT resin fully cured after printing so I would clean the parts as normal, stick them together with resin before post cure.

The long post cure will finish the part along with the full cure of the joints.

If the part isn’t cured to a brownish color it is likely to fail. The full post cure is what makes it temperature resistant.

FredB, this is an important observation.
I thought that it was better to glue with resin the parts BEFORE the curing, to ensure the best strenght.
Are you experienced with this? You already glued parts and you obtained the best result with curing first and then applied the glueing resin?

I haven’t cured parts first and then fused them together with resin. I always use green parts when I use resin to stick things together. After it’s all assembled I post cure everything at once.

My main point is that you need to do a fairly long post cure so it’s best to use resin to stick the parts together first. That way you get a full cure of the part and the joint you stuck together.

When I glue the standard resins together with cynoacrylate I cure first and then glue.

Ok, thx, I fully agree

Ok, it works.
I am still building parts and the whole object is not yet complete, but I glued the first 2 parts with a good result.


First i would design a notch or pin connect into the model halfs or quarters
The slip gap is 3-5%

Second dont use resin use Bondic and a 405mn laser pen

dont forget the 405mn eye glasses

At least as far as Tough is concerned, at least as far as my experience has been, Bondic does not bond to FL resin as well as FL resin bonds to resin.

There’s really no reason to use Bondic or any other adhesive. The way the resin works, a properly cured bond with the same resin you printed with is pretty close to 100% as strong as any other part of the print. For tight/flush fitting parts, you only need the thinnest amount of resin, but you can build up blobs that are just as strong if necessary.

You do want to design something to align the parts. The uncured resin is slick, the parts will slide as you compress the joint. Tack them together with a handheld laser (not a LED, not enough power) while the parts are still “green” and then do a normal post cure and you should be all set.

Using the resin will also fill gaps perfectly, way better than any putty. So if you use glue to quickly attach the parts so that they stay in place you can fill in the gap with resin and then sand down the excess very easily and get a perfect join