Low Budget CNC

by nicengineering

181K1.5K134

Intro: Low Budget CNC

This is the third iteration of my low budget CNC router design, which I began working on when I was in need of a cheap CNC machine some years ago. The idea behind this machine, is that it should be cheap and simple, making it possible for people on a low budget (like me being a student) to build a CNC machine using only a few tools. For that reason most of the parts can be found in a regular hardware store, and the design is slimmed down to requiring only the truly necessary parts.

It should be possible to keep costs below 200 USD including everything from nuts, to cable sleeves and CNC controller.

In this instructable I will do my best to explain how I made this machine, so that you can do one on your own!

Detailed bill of materials, files for 3D printing and drawings are available in this instructable. I have spent some time on drawing the machine in Fusion360, making it possible to take a closer look on the construction.

Disclaimer
A CNC machine is not a toy, be careful when building and using it! I can not be held responsible for injury you might suffer while building the machine or when using it. Nor can I be held responsible for damage that might be inflicted upon any hardware used in this build. Even though I have put a lot of effort and time into this, there might still be missing things in the BOM and faults in my drawings or descriptions - please write me if you find such things.

If you can agree to the terms above, feel free to build and carve!

Features

Work area: 270 x 430 x 100 mm (X, Y, Z) approximately
Precision: Better than 1 mm (based on tests done by me)
Speed: Around 500 mm/min
Suitable materials: Plastics, wood and light aluminum work
The build uses affordable components available in many hardware stores, making it quite cheap!

STEP 1: Bill of Materials

The BOM includes everything I used for this build! Details about the wooden and 3D printed parts can be obtained from the 3D model. Here stl files for printing can also be exctracted through Fusion 360.

Lengths of pipes are very dependent on how deep you drill the holes for them in the wood. Wire lengths are also dependent on how you wire the machine up.

Besides the parts listed in the BOM documents, you will need the wooden parts. They are made out of 16 mm MDF and painted before assembly. The details of these parts can be obtained from the 3D model.

Tools

For making the wooden parts I used a Table Saw, Jigsaw and a cordless drill. Holes for the plumping pipe was done with a flat wood drill, of an apporpiate size. As some parts are 3D printed, you will need access to such a machine. However, It is not strictly necessary to 3D print parts. You will be able to make alternatives without a 3D printer.

STEP 2: 3D Model

I have spent some time on drawing the model in 3D. I have done most of the things myself, but I have used a couple of GrabCAD resources in the model:

And finally the Nut Covers are found here:

Nut Cover

And the Arduino UNO bumper here:

Arduin UNO Bumper

And finally the link for the complete model as shown, is found here:

Fusion 360 model

STEP 3: Drawings and STL

After a few questions regarding the drawings, I have made a couple of technical drawings showing measurements. I have also added the STL files from the 3D model, to make it more convenient to 3D print them.

All measurements are in millimeter !

STEP 4: Assembly

The pipes are both used as linear rails and for keeping the machine together. The pipes are located in holes drilled in the wooden pieces to fix their position. The holes are drilled approximately half way through the wood (i.e. 8 mm) and a center hole of 8 mm is drilled for the threaded rod. Threaded rod is located inside the pipes, keeping the machine together and partly fixing the pipes. This should be evident from the pictures. Measurements of wooden parts and holes in both wooden parts and aluminum angles, can be found in the 3D model. The aluminum angles are seated in the wooden pieces, where a 1 mm deep groove is carved as can be seen from the pictures below. The groove is also present in the 3D model, where measurements can be taken.

STEP 5: GRBL Settings

For running the machine I use GRBL. It has a lot of features, it's open source, gives you an USB interface (in contrast to common CNC controllers) and runs on Arduino UNO.

I have only done light tuning of speed and acceleration, so there might be something to gain here. But it's a balance between current and speed. If you try to increase acceleration or speed, you might need more torque, i.e. you have to give the motors a higher current (thereby heating up the drivers). I have adjusted the current to a level where I do not have to add active cooling to the setup.

My settings you can see here.

STEP 6: GRBL Shield Note

I had a bit of a struggle with noise on the limit switch channels of the cheap GRBL shield I bought. It didn't help to use the NC contact set of the switches, so it's a noise issue. Therefore I placed 100 nF caps between GND and each channel to get rid of this.

STEP 7: Final Notes

A couple of fotos showing what I have used the CNC for is shown here. The two robots are made of 6 mm plywood, where the precision is better than 1 mm. Finally a video of the machine routing aluminium can be seen here. The important thing about routing aluminium is getting the right bit, spindle speed and routing speed. This is of course also true for wood, but wood is just more forgiving than aluminium or pelxi glass.

I hope it's possible to put together the pieces from the 3D model, BOM, pictures and this short instructable. Feel free to comment on the instructable and/or the design.

114 Comments

migo80 1 year ago

Hi, may I ask you the outside diameter of the tubes used for the slide rails? Thanks in advance.

moeck001 4 years ago

Hi, very nice project but I can not figure out which Dremel Type you used for this project? Or which Dremel types fit to the 3D printed mounting.

Kind regards
Manuel

MogensN 4 years ago

Hi,

Yes the dremel alike tool I used came from a Scandinavian store called “Biltema”, but any dremel like tool could be used. It may require some editing of the mounting though...

grahamrigs 5 years ago

That was actually a very creative way to improvise rail carriages.

dpalmer5 5 years ago

I love this! This is a well put together instructable. Could you think this be scaled up to a larger router and table? Maybe 400 mm x 400 mm table with trim router? If so how do you determine the proper steps motors?

AnselmoF1 6 years ago

A CNC machine that needs another CNC or 3D machine to build it? Nahhh, we are tired of that.

nicengineering 6 years ago

Sorry for the late reply... Based on the comments and likes, I don't think the majority is with you on this :) But with a little imagination you can do without 3D printing. I did not use a cnc to cut out any of the wood here and the first versions I built was without the use of a 3D printer :)

AnselmoF1 5 years ago

I only wish to do a following and uptaded comment since almost 9 months had passed. I was not meaning to be rude about you excellent work. In fact, after these 9 months that had passed, I think that your unit is one of the best I have viewed and resembles the best of mounting of the original CNC theory (the overall machining head moving around the workpiece, not the workpiece moving toward the machining head). But the very best part is that, yes, your design can be built very easy without 3D printing or routing the parts. Excellent instructable and very good work.

nicengineering 5 years ago

Thank you for the kind words. Yes it should be possible to build it without the aid of another CNC or 3D printer - but I know that in this particular design I depend on 3D printed parts though. I am glad that you find it useful!

Lithuanian_guy 7 years ago

Hello, do you have any information on how to wire all the electrical parts? I mean the steppers, power supply, CNC shield.

romah 5 years ago

Hi, Great project!
I'm trying to build it and I'm stuck with the electronic part. Wiring diagram would be certainly a + to enable other to reproduce your work.

nicengineering 7 years ago

Hi, I do not have a diagram. But just Google "grbl wiring ". There are many examples to find, and they are all similar.

Lithuanian_guy 7 years ago

Thanks, I've found a few examples, and a video on youtube, that made things clearer. One more question, what CAM software do you use for creating g-code?

nicengineering 7 years ago

Good to hear! I have paid for Lazycam some years ago, so that is what I use for simple tasks. There is also something like Camotics and a bunch of other open source CAM solutions that I have not yet tried to work with. At the moment I don't have a CNC (I sold it a year ago or so), so I am not up to date on the newest open source CAM software out there.

Best regards,

Mogens

D raj 5 years ago

I bought the motors and decided to check it on my drv8825 enabled CNC sheild they spin for a bit and then stop moving and make noise and vibrate is this motor's fault or mine ? And how can I rectify it. Can you please help me PS I am new to all this
Thankyou

KShips 5 years ago

I think this is same problem I had, from memory one of the settings in software needed tweaking might have been the speed or acceleration being too high. I'm about to get back and try and finish this project so no doubt I'll hit that issue again and will update once working.

RobinM174 5 years ago

Hello,

Thanks a lot for this sharing ! I just finished to construct mine, following the plans here.
Here is it at work for the very first try !
Juste some notes : The U bolts need to be 2 inches, instead of 1,5 inches, I had some troubles to find the right one with the right spacing.
Also I made another STL in order to attach the Dremel 4000 (very slightly bigger).

bross2 6 years ago

How do I open the .f3z file in Fusion 360? Fusion wants a .f3d file. If I change the file type to .zip, then extract it, I get 46 separate .f3d files and they appear to be small parts with long numbers and letters for file names. Which one is the assembly?

nicengineering 6 years ago

If you open the Fusion 360 link under step 2 (http://a360.co/2m8K6Dk) You should be able to download the assembly in multiple formats.

CapoC 6 years ago

Hi! How i can do for do this by lasercut? I tried convert the pdf to corel draw, but i can...

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