CNC Mill for under $100

In this video I'm going to show how I built a basic CNC mill. Most of the hardware was sourced from spare / leftover parts I had laying around from other projects and ended up costing me under $100. It has a working area of approximately 250mm x 250mm x 70mm and is capable of milling aluminum (though somewhat rough).

The axes are moved with small NEMA17 stepper motors running at 24V, driven by A4988 drivers. The brain of the machine is an Arduino Uno running GRBL firmware, and G-code is sent to it via. USB from a laptop running Universal Gcode Sender - so everything is open source.

I have a little bit of experience operating a CNC mill, but this is the first one i've built / owned. The biggest learning experience from this build was that everything needs to be tightened up and made as rigid as possible to get good results. Between leadscrew backlash and rails flexing, the spindle could easily be moved +/- 1mm or more, which causes tons of vibration, chattering, rough cutting, and loss of precision. In a future video I'll be upgrading the spindle and beefing up the structure to use 16mm rails instead of 8mm for better rigidity.

I don't recommend trying to build this design yourself, because I created the printed brackets based on parts i had on hand, not what was "optimal". However, if you really want to, the STL's can be found here:

Music Used:

Kevin MacLeod - George Street Shuffle
Serge Pavkin - Atmospheric Ambient
Kevin MacLeod - Groove Groove
Eric Skiff - Underclocked
Serge Pavkin - Fractal

[SalveMonesvol]

You've convinced me to spend $200 on a premade one.

[Duck_side]

Ah yes, the old "under $100" nonsense where the video creator used $300 worth of material he had lying around but forgot to add that to the budget.

[ctrchg]

While I agree with a lot of the criticism, I must say the engineering diligence to make this happen is impressive.

[TheKishinhunter]

the cool thing about mills is that even when they are made from poor quality parts, you can use them to fabricate higher quality parts to upgrade it. mills and lathes are both tools that can be used to fabricate themselves, and i guess we can add 3d printers to that list too now.

[xhrzyms]

Every sixty seconds you spend angry, upset or mad, is a full minute of happiness you will never get back.

[tophalfofabarn]

I think it would really benefit you to chop down the size of this machine. Every time you half the length of a beam, you get one eighth the deflection. This would be a huge increase to the rigidity of your machine, and would be fairly simple to do. The play in the leadscrews can be dealt with by good machining practices, and your Z axis jumping may be helped by counterweighting or adding a spring to keep it preloaded vertically. Shorter tooling and keeping the spindle as close as physically possible to the rails may make this moderately capable of acceptable aluminum parts.

[kienocard]

A great build and fantastic video; I loved how you showed each step in detail. I made a similar one for less than 1$ because I too had most of the parts on hand too ;)

[press]

YT randomly dropped this in my queue and wow am I am glad. Love the humor! I worked 30yrs in precision machine tools (PCD, PCBN) and machining. Finish boring cylinder heads, contouring bearing races, L/D>15 ID drilling (cannulated bone screws)... utter mania, full-on salivation for the deity of "ultra" precision. Drives you crazy with frustration, every day. So I sure can relate to "strapping a beaver" to main drive. And 250$ CNC machine is "too much". :)

I gotta go binge watch all your vids. Well done and thanks.

[makkapakkka]

"How to build a CNC Mill for under $100 when you have over $1000 in spare parts to use"

[davidmashiku]

That is NOT a goofy abomination...it is the birth of the Do it yourself basic CNC mill. Translation... it is awesome. Great work. Thanks for taking the time to make this video

[ryanmacewen]

It's never a waste of time to take on a project that's fun for you, and immensely beneficial if you learn along the way. I built my first 3D printer mainly because I needed one large enough for a particular prototype part. I could have maybe bought one, but could find none with the build volume I needed. It was way more work than I thought it would be. But, in the end, I got my machine, and the knowledge of how to fix or modify anything on it. Upgrades, of your own designs, is just more learning. Great video, and yes title is clickbait. Welcome to YouTube. 🤪

[gabereiser]

CNC for under $100... start with $400 worth of parts...

[TheDistur]

This is cool and clever for someone that has the bits laying around. I think I'd be further ahead to spend a little more and get a kit even if they need tweaking or whatever. Thanks for the video!

[kjade]

Great build.

Here are my thoughts, from one hobby CNC builder to another:

1. Yes, you really have to increase the rigidity of the machine. Use the machine to make sturdier brackets and thicker parts in aluminium. It is not only about the rails.

2. As you said, the play in the lead screw must be less. Either by double nuts or preferably by changing design to tooth belt instead, much better.

3. You have to calculate current and adjust the current limiter on the A4988 to as high as possible. You will get better torque from the steppers. Somehow, every single Youtube CNC-building video creator forgets to do this.

4. Add at least homing switches. When something fails you can restart your milling from the exact same starting point, even if you had to power off in between.

5. The glitch at the end is caused by interference of the motors to the USB connection. Hard to get rid of. The best solution is to make it wireless by using a esp8266.

Good luck.

[dietrashman]

Depending on if you want to do further upgrades to this, you could probably find a way to swap out the spindle with a brushless motor and measure hall effect speed to get both automated speed changes through software and true speed feedbacks for different materials and operations when needed. Might even be able to piggyback another board onto the arduino.

[ste]

Your Arduino CNC hat *has* a spindle drive built into it and it can drive a spindle up to 48v, you didn't need the extra motor driver you built. And you could have then also controlled it through the UGS/Candle software (or whatever CNC GRBL software you're using. I have this system myself and it works fantastic.

[samu]

A lot of people complaining about the click bait title are forgetting this maker put in a lot of hrs and tech knowledge to pass this down to the rest of us. How does he get paid for this valuable time? By getting us here and by the sound of it, kicking and screaming. He baited us, google paid him for the time, and he gave us an actual valuable education. Outside of the temper tantrums, I would say win win for all involved. Ultimately, anyone that came here thinking they can build a CNC machine from scratch with $100 must be one of those people who thinks freebies are actually free. You set yourself up for disappointment. Sorry!

[kzconsulting]

You made me feel the feels with the KSP music for your background music. Very fitting for an assembly video, good on ya!!

[you_just]

Really well done! although, i might not call it a >$100 mill, since step 1 of building it was to pull half the components from your junk drawer ;)

[AadamOmar]

I have a junk drawer as well, everything I don't need or has broken, I take the good parts and keep them for future use
good to see another person recycling old parts :)