I purchased `00 of these for use with a 3D print. They are available in multiple sizes for both SAE and Metric. I went for the smallest I could find – some for 2-56 threads. EZ Lok FL-256-HI, 2-56 Straight Ultrasonic Insert, Flanged – Lot of 100
Since this was the first time I was using these I printed a couple of pieces in PLA to test them on. Here’s a YouTube video covering these inserts – Finishing 3D Prints 101: How to Install Threaded Inserts in your 3D Prints

EZ Lok Threaded Bushings

I quickly found the website for the EZ Lok inserts and then Dimensional Drawings. From there a link to E-Z Sonic™ Ultrasonic Inserts for Thermoplastics and the straight Download page.

This gave me dimensions I could use for my 3D test prints.

Test Print

Test print for the EZ Lok bushingsI simply created four holes for the inserts. I really didn’t probably need to make the recess for the flange but .. shrug .. could so I did.

EZ Lok test print sectional viewHere’s a cross-section. The only really important dimension I think is the 3.2mm (.126″) dimension. I mean .. the process is to heat the brass insert so it melts down into the plastc. I suspect that .126″ dimension is at best ‘nominal’


EZ Lok test print 2-perimeter sectional viewI sliced the STL file in PrusaSlicer. I used the default settings for shells which is 2.

With only 2-perimeters – you can see them at the top, the rings in yellow and orange the top solid surface is shown. Below that is the infill .. think of egg crates (depending on the type) .. not solid but a lattice.


EZ Lok test print 4-perimeter sectional viewI sliced the STL file the second time in PrusaSlicer. This time I increased the shells to 4.

With 4-perimeters the visible top solid surface (in red) is much reduced. That 4 concentric rings go all the way through the model.

PLA Prints

EZ Lok test printsNot much to look at. Up top is the 2-perimeter print with the 4-perimeter on the bottom.

Test Inserts

EZ Lok test print inserted bushingsWorked pretty well. I did a test with both the 2 and 4 perimeter prints. I inserted the bushings easily enough to the 2-perimeter prints (photo left) (video below) with the soldering iron set about 302° F (lowest). I bumped the temp up to about 400° F for the 4-perimeter print which seemed to work ok.

Inserting bushings

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