ruthex M8 Threaded Inserts - 20 Pieces RX-M8x12.7 Brass Heat Set Insert for Plastic Parts - Metric knurled Nuts - Insert by Heat into 3D Printing Components

I used these in some 3d prints and they worked great and held together. Their sizing is also accurate, as I double checked with some digital calipers. I was really bored and even counted how many came in the bag. The bag said 100, and I counted exactly 100. Not bad.

These work very well for your 3d prints. Easy to install even without an insert tip on your soldering iron. I just used a regular tip.

Let me just say this—if you’re printing enclosures or mounts and not using threaded inserts like these… you’re playing life on hard mode.I’ve burned through enough 3D prints to know that tapping straight into PLA or PETG is like trusting a paper towel in a hurricane. That’s where these ruthex M3 inserts come in and save the day like some kind of tiny, brass-threaded Avengers.These things heat-set like butter. No deformation, no bulging, no “oops, pushed too far” drama. The knurling bites in just right, and they seat clean at the recommended temps. I used a Weller iron with a blunt tip, hovered around 210–220°C, and every single one went in textbook perfect. No cracking, no misalignment.They don’t back out when you unscrew either. I’ve tested that plenty—over-tightening, removing and re-seating a half-dozen times—and they still hold strong like it’s their first day on the job.And the RX series? 👌 These aren’t your dollar-store “sorta fits” inserts. These are precision made. Consistent sizing, clean threads, and they ship in a plastic box that doesn’t explode open like it’s trying to test your patience.What I Like:Insertions are clean, controlled, and oddly satisfyingNo burrs or malformed pieces—every single one was usableThreads hold torque like a champ, no pull-outsruthex isn’t playing around—these are real-deal engineered, not sketchy mass-stamped junkWhat Could Be Better:Honestly? Include a small tool or press-fit guide for new users maybe. That’s all I got.Oh, and maybe a reminder that yes, they are hot after heat-setting (ask my thumb)TL;DR:If you’re printing anything that needs to be unscrewed more than once, stop relying on melted plastic holes and upgrade your builds. These ruthex M3 inserts are rock solid, heat-set clean, and make your prints look and feel pro.Your future self (and your screwdriver) will thank you.

These inserts are fabulous. I tried some other "cheap" ones and gave up. I bought these on whim, and was so satisfied with the ease of insertion and mechanical grip. These insert are definitively a great value for the money.

I usually keep a bunch of these on hand to add M3 threading to heavier duty 3D prints. They're consistently machined within very good tolerances, and there haven't been any surprises. Work well with PLA, PETG, and ASA plastics that I've used.

I really like these. Having the design parameters ON the container is genius. The parts are well made.The dividers (like all dividers) fall out and mix up the parts frustratingly.But the biggest issue is these are small diameter. There's only so much toque you can take in plastic being ~0.6 cm out. This is partially made up for by being tall/deep. They are far from junk, and I use them in many places, but when trying to replace a steel part with a print and some inserts, these will be the weak link.Recommended, but with the above caveat.

I purchased these inserts along with a heat gun also found on Amazon with additional tips used for soldering and 3D Printing. I recommend drilling a pre hole first to eliminate overheating the plastic and then simply insert the specific brass tip into the insert and set temperature to about 300ºF. If you flare the pre-hole after drilling and before inserting the insert there will be no noticeable melted plastic around the finished insert. I always set the insert below flush and use a razor blade to remove any residue around the depressed insert.

Very clean looking components. No problems inserting. Hold well so far