Any advice for gluing up a 3D printed helmet?

[Barcslay]

Hey guys! I’m building my first helmet - doing a 3D printed file that I’ve split into 4 parts. I’m not new to prop making, but I’ve never put a helmet together. I’ve done a search here and on google and have found a few different methods; I just wanted to get an idea of what you guys are doing these days for 3D prints - I’m using PLA+ for the filament.

What do y’all recommend for attaching the 4 quadrants of the helmet? CA glue, 5 min epoxy, soldering iron welding trick? Other?

Also, with those of you who’ve done 3D printed helmets, do you recommend fiberglassing the inside afterwards?

Thanks a bunch

 

[Props3D]

Plastic Bonder 2 part urethane works well for me, I use acrylic paste after for smoothing it all out, you can also use 2 part resin like 'smooth on' as both a finish and to reinforce the strength, the acrylic makes it look great but does nothing to hold it together.

As long as you use a good PLA with a bit of flex like those marked 'strong pla' you don't need to do anything else. Make sure you use at least 3 outer walls if you're not going to reinforce it though, just a suggestion.

 

[Halliwax]

I’ve always had good luck with 2p-10 glue

 

[TazMan2000]

I drill locator holes in all the parts and glue brass pins on one side of the pair. It takes a bit to get it fitting together perfectly, but when the pins are there, its almost impossible to get wrong and it saves time with filling and levelling uneven joints. Yes, you can use bondo or filler to repair mismatched joints, but it takes a lot of time, filler and sanding to correct something uneven. A little investment in getting the joints perfect will pay dividends later.
With PLA, I usually use CA glue.

TazMan2000

 

[Halliwax]

I drill locator holes in all the parts and glue brass pins on one side of the pair. It takes a bit to get it fitting together perfectly, but when the pins are there, its almost impossible to get wrong and it saves time with filling and levelling uneven joints. Yes, you can use bondo or filler to repair mismatched joints, but it takes a lot of time, filler and sanding to correct something uneven. A little investment in getting the joints perfect will pay dividends later.
With PLA, I usually use CA glue.

TazMan2000

The pins are a excellent idea!

 

[Barcslay]

I drill locator holes in all the parts and glue brass pins on one side of the pair. It takes a bit to get it fitting together perfectly, but when the pins are there, its almost impossible to get wrong and it saves time with filling and levelling uneven joints. Yes, you can use bondo or filler to repair mismatched joints, but it takes a lot of time, filler and sanding to correct something uneven. A little investment in getting the joints perfect will pay dividends later.
With PLA, I usually use CA glue.

TazMan2000

So you drill your holes after the print is finished? I modeled with the holes included already but forgot to add a couple, and was worried that drilling wouldn’t do much since the infill isn’t completely solid

 

[TazMan2000]

So you drill your holes after the print is finished? I modeled with the holes included already but forgot to add a couple, and was worried that drilling wouldn’t do much since the infill isn’t completely solid

Sometimes modelled holes work as well but it depends on the orientation. There should be enough wall thicknesses to accommodate the drilled holes. For a helmet, I recommend at least 4 layers on all sides, sometimes more.

When the holes aren’t pre-modelled, I usually use a knife to etch the pin hole locations on the outside. Your holes probably never going to be perfectly oriented on the first try, but I fill the improperly drilled hole with CA glue and re-drill a new hole. Sometimes bending a pin will also work. There is a bit of trial and error with this process, but it’s better than than eyeballing when gluing.

Before I used this idea, I’ve glued pieces together and realized almost immediately that they were slightly off. I tried to separate them and ended up ruining both pieces that I’ve glued together because the CA glue joint was so strong. 24 hours of printing wasted.

The pins also add a bit of strength as well.

TazMan2000

 

[Props3D]

On the subject of pins, if you know how to edit the models I add 1.6mm reference holes then use a small drill bit to expand them to exactly 1.75 after printing, then you can use bits of filament for the reference holes that are both free and add strength since they take glue well.

 

[Vagabond Elf]

Normally I'd recommend against CA glue, because while it's strong it's also very brittle and has basically no strength if force is applied along the joint (as opposed to pulling the two pieces apart). But with something like a costume helmet, it shouldn't be subjected to many shocks - so as long as you don't drop it, CA should be fine.

My normal suggestion would be epoxy or E3000 E6000, but I wouldn't actually want either of those substances near my face, so not great options for a helmet.

 

[Halliwax]

Normally I'd recommend against CA glue, because while it's strong it's also very brittle and has basically no strength if force is applied along the joint (as opposed to pulling the two pieces apart). But with something like a costume helmet, it shouldn't be subjected to many shocks - so as long as you don't drop it, CA should be fine.

My normal suggestion would be epoxy or E3000, but I wouldn't actually want either of those substances near my face, so not great options for a helmet.

im not coming off cocky or trolling, but im a huge fan of e6000 and use it all the time. i have never heard of e3000 and curious if this is a different version of e6000, i have done a google search and the closet thing i can find is carpet adhesive. is the carpet glue what you are using, or was e3000 a typo?

 

[Vagabond Elf]

im not coming off cocky or trolling, but im a huge fan of e6000 and use it all the time. i have never heard of e3000 and curious if this is a different version of e6000, i have done a google search and the closet thing i can find is carpet adhesive. is the carpet glue what you are using, or was e3000 a typo?

It's a typo. (But never be shy of asking! The only stupid questions are the ones designed to made the answerer look dumb; any honest attempt to gain knowledge or clear up confusion is a good thing!)

In my defence, I spent 2 hours yesterday digging my work van out of a windrow (of snow, not wheat) after sliding straight accross an intersection, and then delivered over 100 boxes of food today.

Honest that's it, and not because I was using the e6000 without a respirator!

 

[Halliwax]

It's a typo. (But never be shy of asking! The only stupid questions are the ones designed to made the answerer look dumb; any honest attempt to gain knowledge or clear up confusion is a good thing!)

In my defence, I spent 2 hours yesterday digging my work van out of a windrow (of snow, not wheat) after sliding straight accross an intersection, and then delivered over 100 boxes of food today.

Honest that's it, and not because I was using the e6000 without a respirator!

thanks for the reply, i love e6000 so when you mentioned e3000 i was like " i need to learn more about this! " lol

sorry to hear about the snow.. we missed that storm thank god..

 

[Vagabond Elf]

thanks for the reply, i love e6000 so when you mentioned e3000 i was like " i need to learn more about this! " lol

sorry to hear about the snow.. we missed that storm thank god..

Most of that snow was a week old... the problem was it had been 2 degrees above freezing and raining, so the roads were sheer ice. Every time we go the van a little loose it just slid back downhill into the windrow again!

But the sympathy is appreciated. It's been a hell of a week!

 

[Halliwax]

Eeerrr I hate that weather, be sure to stay safe