Home-made CNC milling machine

For the uninitiated, a CNC milling machine is basically the opposite of a 3D printer. With a 3D printer, you’re adding medium from a nozzle to a blank space to create an object. A CNC milling machine starts with a chunk of medium and removes parts of it to create an object, drilling out parts of the medium with great precision while moving its spindle on more than one axis.

CNC milling machines (the CNC means Computer Numeric Control) are really expensive.

Screengrab from eBay today

Screengrab from eBay today

So Colin May did what any thinking engineer would do to bring the price down. He built his own, using a Raspberry Pi for its brains.

CNC machine

Colin says:

My friend and I thought about building a CNC Machine for a while. But we didn’t want it to be just an ordinary CNC Machine. We wanted to make a very unique machine that could have very unique attributes. We set out to make a CNC Machine that could do different types of Machining. For example, routing, laser engraving, 3D printing, drag knife, etc. We took about a few months to design the basics of the machine. For example, what kind of linear motion we would have for each axis, what kind of material we would use for it, what kind of style to make it, etc. We chose our build area to be 24″ X 24″ X 7″. After those few months of finalizing everything, we took our first step into physically making the machine. Note: This is made for the average consumer, for home use, and for someone who doesn’t have the money to invest in a $1000 CNC router or 3D printer.

Colin’s machine is still a work in progress, but it’s showing great promise, and we’re very interested to see where he takes it next. Here’s some prototype output:

chillipepper logo

First test of the machine

test output

Second test

And here’s some video. (Turn the sound down if you’ve got a dentist phobia.)

Colin is intending to add extra functionality: 3D print capability, and some other machine tools – to the setup. You can follow his build and replicate it over at Instructables. Thanks Colin – we’re looking forward to seeing more!



karan avatar

Awesome.It’s a really cool pi project and certainly a great way to save money.

AndrewS avatar

I wonder if there’d be any power-saving to be made if the drill was powered-down during the long sideways strokes? I guess it depends how long it takes for the drill to spin-up to full speed again.

I guess with a generic (and customisable) X-Y-Z stage there are all sorts of add-ons you can imagine adding to it. Fun!

PaulR avatar

You might want to look at “Mostly Printed CNC”:

It can go to 2ft square. Total cost around US$400.

Dutch_Master avatar

Very nice.

@Andrew: you could add a sensor to measure the speed of the motor and program the device to only start cutting again when the motor has reached its minimum cutting speed. If the motor is PWM controlled, measuring the BEMF is a reliable indication of motor speed.

Richard B. avatar

Actually the wear and tear on the bearings, from a high number of on/off cycles (especially on its highest speeds), would probably outweigh any savings in power. That is a measure you might look into if you were running on battery power, but again would the wear on the “spindle” be worth it.

You went right by using threaded rod for all your axis.

Very nice project. You might be able to do light metals like Aluminum (Aluminium, LOL) or brass sheet.

Could you add limit switches with the number of GPIO available?

A recommendation; seal all that wood! I had a Printrbot (3D Printer) Simple Makers kit that was Baltic Birch plywood. I had trouble with temperature and humidity changes. Screws/fittings always getting loose. That caused all kinds of day to day accuracy changes.

AndrewS avatar

Re: bearings – good point, I hadn’t thought of that. You can tell I’m a software-guy rather than a hardware-guy ;-)

Robby avatar

Excellent ideas!!! Leads me to build one for an

James Bergman avatar

This is really impressive. I have wanted a CNC machine in my workshop for a while. Ever since I found out what they can do and how they are used in machine shops. However, the price is an issue. I also doubt that I could build one like this. It is a really impressive setup.

Adam avatar

Great work

Aidehua avatar

So how would one program step motors for a manual mill machine (Bridgeport)? I’ve seen conversions for these machines before. Way too expensive. I bought one from a buddy and would like to convert it to CNC using step motors or servos. Any ideas out there?

Daniel Jones avatar

Thanks! Nice Article.

With the cost of housing increasing, the need for affordable custom homes is really turning into a niche for some companies.


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