Please click through to the ongoing project #Minamil: a minimal CNC mill !

This project here was temporary for the 2021 HaD Prize

Winning a finalist slot was great and much appreciated! – and done!

Thanks for checking out my project! For whatever brought you here, please jump over to #Minamil: a minimal CNC mill where this project started and continues. If you wish to follow future updates, please follow that project instead of this one.

This project here was created for the #Supplyframe DesignLab: 2021 Hackaday Prize competition, where it won recognition as a finalist. !. Conclusion of the competition completed the life cycle of this project.


This "new" project represents current development of #Minamil: a minimal CNC mill with an overview of prior work curated for entry in the #Supplyframe DesignLab: 2021 Hackaday Prize competition -- without breaking continuity of the main project and leaving behind people who have followed there.

Apologies, dear Hackaday Prize judges. I had all the best intentions to make substantial new final video and additional content, but didn't get it done.

This little CNC mill works well enough to produce an eye-candy demo video:

...and mill fine-pitch circuit board traces:

What little CNC mill?

Minamil: a minimal CNC mill

First there was #CDCNC, a highly-constrained just-barely-functional one-off toy built by improvisation with found junk and simple tools.

Here I'm developing an idea that came from thinking about whether or not there is any space between a dumb stunt like CDCNC and a commercially (i.e. efficiently) produced entry level CNC mill.

In contrast to CDCNC, this is about reproducibility from a simple BoM, economical access to laser cutting, and instructions for building your own sub-mini CNC mill.

Next there may be #"Desk Accessory" CNC Milling Machine. The lead image montage includes a couple views of the current proof-of-concept frame+enclosure (* with a currently unpublished extended Z axis).

Selected Log Entries

Some of these link back to the mainline project.

HaDPrize 2021 - Challenge 5 - Reactivate Wildcard

Wildcard: to refresh or redefine the technologies we know and love in order to create a brighter future for all

A technology problem facing people today...

Although we may be getting over it, COVID-19 closures and remote learning have been pretty hard on anything that might have smelled like shop class or hands-on practical education, including opportunities to practice CNC programming and machining.

Personal 3D printing has become common. While laser cutters remain costly to own, their straightforward operation can work well as a commercial service or community resource.  Meanwhile, "Subtractive" CNC milling/routing, the CAM part of CAD/CAM for 70 years, remains relatively less accessible. Obstacles include cost, space, mess, and complexity. Potential benefits of access to CNC milling include working more kinds of material with greater precision, and, for tackling the complexity, entree to a valuable career.

...and an idea of what a solution might be

This project aims to significantly reduce the entry cost of personal CNC milling by way of an apparently unprecedented combination of:

And also some more apparently novel (?) spin-offs with wider utility:

a couple of assumptions

Let's take care of this up front. The "lowest cost" premise includes a couple of assumptions -- or selection criteria for identifying circumstances where this makes sense.

Say what‽

"apparently unprecedented"

I’ve been logging work on this project on for about a year and posted an Instructable about five months ago. Both sites have drawn 10k± views and so far no one has mentioned a similar precedent. Please comment if you know of one, or eleven.

"assembly from ready parts vs. fabrication"

Certainly many people have made very low cost CNC machines from scavenged parts, scrap materials, an equipped shop, and a fair idea of what they were aiming for.

This project presents a design based on two main assemblies – the X+Y axes, and the Z axis+tool clamp – built from a few specified hardware parts and some laser cut flat pieces following detailed illustrated assembly instructions. The frame that holds the Z axis over the X+Y axes does call for ad hoc construction from available material, but that can be made to eyeball precision from practically any rigid flat-ish material and would not benefit from over-specification.

"lowest cost"

Let’s say “under US$100” to allow for whatever I’m forgetting. All parts and material used in the 3-axis motion mechanics can be ordered or bought locally in my part of the US for under US$50 (+tax) - verified October 2021. About 20% of that – US$10 for 6mm steel rods – may be scavenged from many kinds of discarded printers, copiers, etc. A complete kit of electronics costs about US$10 plus a power supply which may be something like a repurposed laptop power brick. Maybe add a little for wiring incidentals if not already at hand. I made the first machine frame from garbage-grade scraps and 8 drywall screws. A 10 piece lot of 1mm end mill bits costs <US$10.

For comparison, the lowest cost I’ve found for the most extremely cost-reduced version the generic “3018”-type 3-axis machine that I’ve found was about US$100, delivering less precision for more money. Better built “3018”-type machines for $200 or $300 still show less precise circuit board milling among results that I’ve found published by others.

As already stated, I’m assuming access to a laser cutter and a rotary tool.

"good precision"

While not big or strong, this design does turn out pretty good precision.

Small Bevel Gear
Bevel spider gear for a complete differential - Click image for 3m18s video
Circuit board traces
Fine-pitch circuit board traces - Click image for 1m43s video

"table-top use and shelf storage in home vs. fixed installation in garage or shop"

With just a little more attention to constructing the frame, again with found scrap, it can be made with "doors" that close up close for storage or unfold into an enclosure, A vacuum drawing through the base pulls floating dust down into the enclosure for clean tabletop operation. The telescoping action of the slides gives the parked machine a compact footprint smaller than a letter/A4 sheet of paper.

Stapler for scale; banana was down.

Click the image below for a video showing setup & teardown.

Enclosed frame
Unfold to use; contain the mess; put away - Click image for 3m13s video

The FAQ and Rules include overlapping lists of criteria to be considered for assessing contest entries, A unified set of criteria and notes in response follow.

Is this a unique solution to a particular challenge facing the world today?

Learning “subtractive” CNC machining requires hands-on experience. Recent pandemic-related restrictions have curtailed necessary access to machines for learning. CNC machines available for personal ownership tend toward exclusively high cost or to sacrificing much of the precision that would characterize a learner’s experience of using a “real” CNC machine. And cheaper CNC means more people learning organically and making more kinds of things.

As far as I know at this point, this really is

Also the whole includes parts that

How effective of a solution is the entry to the challenge it is responding to?

For the 3D mill

For a single linear slide

For making anything from laser cut flat material

For realizing actual low backlash with low cost linear actuator

For robust tool clamp from simple flat parts

Early dev stage: low cost high speed spindle

How thoroughly documented were the design process & design decisions?

tl;dr: tried an idea for a least possible step up from a CD/DVD optical deck and it worked so I kept going -- here's the one big read.

I think I can fairly say: documented more thoroughly, or at least with more words, than most people will want to read.

Or a little more selectively:

How ready is this design to be manufactured?

For either the 3D CNC design or a single linear slides for use in other applications:

How easily can this design be implemented by other people in future projects?

"Easy" is a primary project goal!

To be clear, I expect this to continue as a DIY project rather than a turn-key consumer item ready to chug out all the best parts on delivery. By "easy" I mean easy for hack-ish people with aptitude for assembling something from pieces, and then learning a tool that returns delayed gratification for initial patience. That said, making it easier for more people to get started on the 3d CNC “subtractive” learning curve for is also a primary project goal.

And here's the how:


How complete is the project?

Two answers:

  1. It works well right now!
  2. I think this project has lots of potential for further development!
    • validate buildability
    • improve build documentation - try video
    • given rising price of the specific CH-SM1545 motor and falling prices of similar but longer generics: adjust dimensions to fit the longer screws which are no longer much more expensive and apparently available from more sources. (oh, heck yeah - price bumped again)
    • optimize flat part details to reduce commercial laser cutting cost
    • adapt for more expensive but faster-cutting material, e.g. acrylic, to net reduce commercial laser cutting cost
    • try again 2x motors for X & Y - first try effective when synced but too easy to un-sync; try again with limit switches & soft limits
    • test idea for low-cost high-speed spindle made with similar laser cut hardboard construction