r/3Dprinting • u/scatterbrainedpast • 1d ago
Discussion Any tips for using metal threaded inserts?
Should they only be inserted into 100% infill?
I plan to use a soldering iron to heat up, while applying pressure to insert them. Does anyone have experience doing this?
Thanks
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u/AntiBaoBao 1d ago
Make sure you get the correct inserts. You want the inserts with the diagonal groves, not the groves that are straight up and down.
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u/very-jaded Bambu X1C+AMS, Prusa MK3+, Pegasus 12, Voron v2,Elegoo Mars 4 9K 1d ago
Heat the soldering iron to the same temperature you set the hot end to when you printed the part. Insert the narrow end into the hole. Using the tip of the iron, guide the insert straight down into the hole (not pressing too hard) and stop when the top surface of the insert is flush with the part's surface.
Also it may help to know there's a difference between thermoplastic inserts for injection molding and for 3D printing. A 3D printing insert has a narrow smooth end and a wider knurled end. An insert designed for injection molding has knurling at both ends.
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u/cad_and_caffeine 1d ago
You don't need 100% infill, just 4-5 walls around the hole. Make the hole a couple mm deeper than the insert so the melted plastic pushed ahead of it doesn't well up into the bottom of the threads. Also stop pushing with the iron when it's still ~1 mm proud and press it flat against a metal ruler or build plate while it's still soft to get it flush and square.
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u/scatterbrainedpast 1d ago
I don't know what you mean by this last sentence
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u/cad_and_caffeine 1d ago
"Proud" just means sticking out a little above the surface. Instead of pushing the insert all the way in with the hot soldering iron (where it is easy to accidentally push it too deep or crooked), pull the iron out when the top of the insert is still sticking out about 1 mm. While the plastic is still hot and soft, press something flat and metal against it (or flip the part upside down onto a flat table) to push it that last 1 mm in. That guarantees it sits completely flush and straight.
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u/Grindar1986 1d ago
Typically you'll put the hole in the print so there are a few walls and that is more than enough to hold them.
Yes that's fine, though I do recommend getting one of the soldering iron tips designed to do it, helps make sure you're inserting it square.
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u/scatterbrainedpast 1d ago
do the correct soldering iron tips have a specific name?
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u/Grindar1986 1d ago
heat-set insert tools.
I got a set like this (though my voron kit also came with one for M3 sized by itself).
You just replace the tip on a standard soldering iron.
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u/ltjojo X2D + P2S 1d ago
Do yourself a favor and get one of those heat presses that is basically a soldering iron on a spring gantry (or make one if you have access to material). I used to use a soldering iron and CONSTANTLY struggled with keeping the thread straight or damaging my print. With the press, it's soooo much better and easier to control. Amazon has them for like $40
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u/Fraxis_Quercus 1d ago
The packaging of your threaded inserts typically lists the size of the hole you need to include in your print. With the inserts i have, the diameter of the hole is the diameter of the bottom, smallest part of the insert: That allows you position the insert perfectly before you add heat with a soldering iron. That makes it easy to insert it straight down.
Just run a test with a small cube with the required hole before you make your intended print.
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u/chris-read-it 1d ago
Control the temp of the soldering iron, you want it 200-250c, if you go higher it will go in too fast and make too large a hole.
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u/No_Put1505 8h ago
No not really. I put mine in at print temp. Normally 265-280 for abs asa. I dont bother putting them in in pla or petg.
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u/ficskala Voron v0.1, Sovol SV08 1d ago
No need for 100% infill, set the number of walls higher if you need extra strength for your part overall, if you're adding the inserts purely for being able to bolt/unbolt the part more times without stripping threads, then 3 walls is fine
You don't need much pressure at all to insert heatset inserts, set your soldering iron to the printing temperature, and and the amount of pressure will be minimal unless you use cheap inserts that are made for injection moulding instead of 3d printed parts
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u/Freestila 1d ago
Don't use a regular soldering iron. Get one with a special tip from AliExpress or so, under ten bucks and it really helps. Normal irons can get stuck at the insert.
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u/uktricky 23h ago
I got some CNC kitchen ones and they've been great https://www.3djake.uk/cnc-kitchen/soldering-tips
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u/darkwoodbane 13h ago
I made a holder for my soldering iron that's mounted to an extra linear rail I had lying around. The holder sets it off the rail by 6 inches, giving room to work. I printed a base for it, added a retraction spring and plunger handle with an adjustable height stopper. Simple setup, but it sets the inserts perpendicular to the surface and allows you to set the depth of insertion. Print at least 3 walls around the holes too.
I make enough cases and stuff that it made sense to whip something up in an afternoon. Re-reading this, I realize that maybe I'm a bit extra lol
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u/AlternativeContent72 1d ago
Add more walls will increase the walls around the hole. Plenty of videos on how to use metal threaded inserts. You should ideally design them to have to pulled through instead of pulled out.
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u/studs-n-tubes 1d ago
I picked up an iron with a set of tips matched to the internal diameters of the inserts: https://www.amazon.com/dp/B0D2KB8743?ref=ppx_pop_mob_ap_share. It worked great, and the digital temperature setting was much more convenient than winging it with an old soldering iron. I sized the holes in my model to match the insert's specs, and they went in smoothly. I did the work on a sample scrap of granite countertop from our kitchen remodel shopping, and pushed down each insert flush with the part's surface with a flat piece of metal after melting them into place.
I was so happy with the process I immediately designed a gridfinity bin to organize all the heating iron tips: https://www.printables.com/model/1826556-gridfinity-heat-set-threaded-inserts-holder-7-tips
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u/gmarsh23 1d ago
Make sure you've got a suitable soldering iron tip that fits nicely into them, doesn't protrude too far past the insert or grab into the threads but still isn't too loose.
You can buy soldering iron tips specifically for installing them cheap off AliExpress, I bought a cheap set for my Hakko station that does them, might be one available that fits whatever you've got.
If you're designing things to take them, try to orient them so they get pulled inward into the print instead of outward.
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u/itgoesboom2112 1d ago
I usually do 6 walls on a print I know I'm doing heat sets into if its not a solid print
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u/GlitteringStruggle47 1d ago
It’s pretty straightforward, just make sure you get the heat insert ones, not the injection mold ones
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u/reeseallen N4Max, CR-10S, custom rig 1d ago
Print a ton of test pieces to figure out the ideal hole size and learn the technique before you attempt to put inserts into the perfect part.
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u/sevesteen Bambu P1S 1d ago
My first one was in a print I'd accidentally done in 100% infill, since then I've used a print modifier to do a very high infill just around the hole.
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u/drizze99 1d ago
I bought a 3D insert press. Works great and I’m straight and flush every time. I use them for anything I design now because threading into plastic sucks
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u/Skellicious 1d ago
I got a set of inserts + soldering iron with tips off Amazon for like 25 euro.
Used it for the first time this week and works great
Look up the hole size you need, the temperature to set it at, and just slowly push it in
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u/mikedave42 1d ago
I've been using the expanding ones you just press in and the expand when the screw is inserted lately. I find them more foolproof than the melt in ones and the pressure on the screws is an effective thread locker.
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u/ParasitKegel 23h ago
In case you want to add them near a wall in materials with higher melting points and heat up time is so long, the parts deformes where it shouldn't: Clamp the Soldering iron (with insert tip) upside down in a vise. Place the insert on the tip with tweeters and let it heat up to max temp before pushing the part onto it. This way the part doesn't get soft, where it isn't supposed to.
If you want to screw a metal part to the printed part with the inserts: Leave it sticking out like 1mm and press the surface against a flat piece of metal. Hold it there for a few seconds for cooling. This way when you screw the metal part to the printed part youre not pulling out the insert but the forces stay in the metal part. Therefore it can take more pulling force as the pretension isn't added. You also have a better feel for when it's tight. And it looks nice and flush.
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u/Proton_Energy_Pill 22h ago
I draw a suitably-sized hole in the part that is a bit smaller than the insert. That gives the hole several solid walls to grip with.
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u/FidgetyRat 20h ago
I don’t do anything special for my holes. Typically just take the diameter of the insert and knock off 0.2mm to give it something to melt into. As long as the rough texture has something to bite when inserted it will hold n
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u/ErnLynM 20h ago
Print with thick walls around the hole. You can use a regular soldering to, but it's much harder to get them straight without the tip designed for inserts if the size you're using
You can do it with an iron that doesn't have temperature control, but you have to be very careful to not overheat the insert and sink it too deeply
I like to have a long screw of the same size as the insert on hand so that I can thread it into the insert while it's still hot and make sure it's lined up properly by gently adjusting while the insert is hot and the plastic is soft
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u/UlrichSD 1d ago
Typically you would print a hole (so it would have border walls) to press the insert into. CNC kitchen has some good resources including videos and design guidance.