An attractive orange CNC mill sitting ona bench.

3D Printed Milling Machine Is Solid As A Rock

April 13, 2025 by Tyler August 59 Comments

There are no shortage of CNC machines in the DIY space these days, but sometimes you just need to do things your own way. That’s what [Chris Borges] decided when he put together this rock-solid, concrete-filled CNC milling machine.

The concrete body of this machine is housed inside a 3D printed shell, which makes for an attractive skin as well as a handy mold. Within the concrete is a steel skeleton, with the ‘rebar’ being made of threaded rods and a length of square tubing to hold the main column. You can see the concrete being poured in around the rebar in the image, or watch it happen in the build video embedded below.

An image of the main column of [Chris]'s CNC mill as the concrete is added. The steel reinforcement is clearly visible. — In goes the concrete, up goes the rigidity.

All three axes slide on linear rails, and are attached to lead screws driven by the omnipresent NEMA 17 steppers. The air-cooled spindle, apparently the weak-point of the design, is attached to a pivoting counterweight, but make no mistake: it is on rails. All-in-all, it looks like a very rigid, and very capable design — [Chris] shows it cutting through aluminum quite nicely.

Given that [Chris] has apparently never used a true mill before, this design came out remarkably well. Between the Bill of Materials and 45 page step-by-step assembly instructions, he’s also done a fantastic job documenting the build for anyone who wants to put one together for themselves.

This isn’t the first concrete-filled project we’ve highlighted from [Chris], you may remember seeing his lathe on these pages. It certainly isn’t the first CNC mill we’ve covered, either.

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Casting Concrete With A 3D-Printed Mould

July 1, 2024 by Jenny List 20 Comments

We’re accustomed to covering the use of 3D printing in casting, usually as a lost-PLA former in metal casting. That’s not the only use of the technique though, and perhaps one of the simplest is to use a 3D-printed mould for casting concrete. It’s what [ArtByAdrock] is doing in their latest video, casting an ornamental owl model.

The first part of the video below the break deals with the CAD steps necessary to produce the mould, and depending on your CAD proficiency may not be the most interesting part. The process creates a mould with two halves, a pouring hole, and registration points. Then a 3D printer produces it using flexible TPU. The pour is then simplicity itself, using a casting cement mix at a consistency similar to pancake batter. The video shows how a release spray provides easy separation, and the result is a fresh concrete owl and a mould ready for the next pour.

We can see that maybe readers have only so much space in their lives for concrete owls, but this process could be a valuable part of the armoury when it comes to making some less decorative items. It’s not the first time we’ve looked at this type of work.

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