Cheapest home-made 3 axis CNC

Projects General Guidance
1

Hello everyone!

For a long time I am planning to make a home-made CNC. As a student of ME that has a low budget limit I am trying to mini-maze the expenses so I am really looking to use as many "free" parts as possible. By saying "free" I am talking about stepper motors out of old printers and other mechanical components.

I have read most of posts talking about this topic so I can say that I am well informed but I would like to get some guidance from professionals. My main goal here is to make a CNC with a budget around 100 dollars.

I think I should not have problems with the mechanic/construction part of my project, however, I do think I will have problems with the electrical/programming part since you don't really get inloved into that by studying ME (except some programming).

My idea of the electric circuit would be something like this:

  1. As the main component I will use Arduino UNO which I got with the arduino starter kit.
  2. Secondly I will use 3 stepper motors that I got out of old printers.
  3. lastly I will buy 3 EasyDrivers for stepper motors.

The circuit follows this idea: http://www.instructables.com/id/How-to-wire-an-arduino-based-3-axis-CNC-machine/

For the software part, I would use the free opensource g-code-parser and CNC milling controller GRBL Using Grbl · grbl/grbl Wiki · GitHub

I would really like to hear your opinions on this, especialy from people that have already done something like a CNC or 3D printer or anything involving Arduino and stepper motors :slight_smile:

Regards,

mcluka

2

You will have to make a substantial investment in precision parts.

Normally 16 mm dia ground rods are the minimum recommended size along with their associated linear bearings.
These are not cheap.

Anything less and you will not get the required stiffness to avoid tool breakage.

There was a drill Only design some years back that used ball bearing drawer guides, not a mill though , and from memory was not exactly cheap either.

A decent spindle will also be around 100 to 300 alone.

The steppers and electronics are actually the cheaper parts used.

3

free software to use a DOS based PC

http://www.dakeng.com/turbo.html

it uses the PC printer port as the output.

no programming is required.

sorry, but it would be much harder to use the Arduino as the home based CNC hobby is really solid and everything you need has been done hundreds of times.

if you must use the Arduino, google arduino cnc

as was mentioned, work=force=power. a simple CNC machine will bend steel bars when trying to drill or cut metal.

if you want to cut wood and such, a dremel or similar can be the spindle and you can start/stop that with a relay.

4

dave-in-nj:
free software to use a DOS based PC

sorry, but it would be much harder to use the Arduino as the home based CNC hobby is really solid and everything you need has been done hundreds of times

I have seen a makerbot which is arduino powered where the extruder was fitted with a dentists drill.

Software used was mach3 which is free and widely used for cnc.

Not sure what the most common controller board for cnc is though.

5

What kind of CNC? Mill, lathe, pick and place, cotton candy spinner thingy?
What materials do you plan on machining?

6

when building a cnc machine you need to work out what you are going to cut first, if you wont fast or slow cutting speeds and size of material to be cut.
then go from there and size does matter.

7

Boardburner2:

dave-in-nj:
free software to use a DOS based PC

sorry, but it would be much harder to use the Arduino as the home based CNC hobby is really solid and everything you need has been done hundreds of times

I have seen a makerbot which is arduino powered where the extruder was fitted with a dentists drill.

Software used was mach3 which is free and widely used for cnc.

Not sure what the most common controller board for cnc is though.

Mach3, last time I looked, was a few years ago. it was easily the best thing going on a WINDOWS PC, but you need to run windows and one of the features was that it figured out how to by pass the windows getting in the way and messing up the timing.

most people have an old dos box laying around. turbocnc is much easier to learn, but less attractive to watch.

interface to either is super simple an older machine has 5v on the parallel port. newer ones are 3v or even less.

you can control a darlington arrray. step and direction on a breakout board. if you can make a pcb, this is childs play.

if you have an old pc, you can run a stepper by 4 pins on mosfets.

8

I am planning to cut wood and plastic, maybe aluminium but I am really just leaning towards plastic and wood.

9

However I would like to know what do you think about the electrical components which I am planning to use, I mean is it okay or is it to complex?

10

You need to consider the mechanics.

Printers use light head and thin drive belt.
A milling head has more mass which will deflect a thin guide bar , also could stretch the drive belt.

Driving at a much lower speed may work.

The previously mentioned makerbot had a very light dentist drill ( pneumatic ) .

You say you are a student of ME , maybe wait until you have covered mass and acceleration before starting.

Electronics are purely for control and have no mass.
They will do anything you want once you have specified the mechanics you are using.

Printer bits can be used to build an engraver or makerbot , with cnc however the mass and forces are very much higher.

11

I will probably have to get more powerful step motors, however I will post the construction here when I will have the 3D design so you will be able to comment on that.

12

So long as you keep the step speed low , printer motors may suffice anyway.
Ive had some sucess doing that.

As said the problem is with the mechanical arrangements.

With the right belts and toothed wheels you get gearing and force.

Buying relevant belts and wheels is possible but expensive.

Just depends on how lucky you get with printers.

Im in uk and rules her do not allow scavenging from tips anymore.
Loads of usful stuff seen but cannot touch it..

13

Lots of people here saying it can't be done with an Arduino, or with printer stepper motors.

The Shapeoko uses an Arduino with GRBL. And the 60oz-in stepper motors can be found in old dot matrix printers. I have a bunch from Apple Imagewriter II dot matrix printers. The problem is that most of those old printers are long gone.

It uses small aluminum rail.

I'd use a small trim router rather than a Dremel. Dremels are great hand-held tools, but they do have some runout and there is some give between the bearings and the case. For a small, light head, you might also consider a rotary hand tool where the motor and handpiece are separate and just hang the motor over the machine.

I am also working on a machine to cut wood, plastic, wax, and aluminum plates. Just don't expect to cut through any of those materials in one pass. But then, you probably know that. I don't think it can be done for $100, though, without a -lot- of trawling through the trash.

14

I've been interested in the same thing.
I also don't have a lot of spare money lying about and it doesn't have to be big or powerful, here you go.

Check this out. Less than a $100.
Mantis 9.1 xyz cnc. Mostly plywood or MDF. Pretty good precision. Slow, but pretty accurate, if you build it well.
If you have access to a CNC router, there is a g-code file you can download to mill all the wooden parts.
There are lots of Youtube videos of how to build it. There is a parts list. Easy to modify it to use different motors, or a Dremel Moto-Tool, or a grinder. It might even hold a 3D printer head.

http://makeyourbot.wikidot.com/mantis9-1

Using Grbl · grbl/grbl Wiki · GitHub Runs g-code on an Arduino
http://www.sketchup.com/ Free CAD program. I just started learning it.
http://www.makercam.com/tutorial.html I think this creats g-code from CAD files, but I haven't looked closely yet.

You can find the motors cheaper on ebay, if you don't mind waiting on the slow boat from China.

John

15

im looking at building a cnc xy platform,maybe a z axis too,the thing is ,im going to use a laser to cut and etch wood ,plastic,a 5.5w diode laser will cut 3mm wood ,for me this is fine ,if you need a cutting TOOL maybe not so fine,but the laser does not give back pressure while cutting,ans so does not need such a stiff framework,not that a flimsy frame will do,but high precision can be had from less expensive construction.
Build a good laser cnc then sell it to buy the bits you need for a mill cnc.Then use the mill cnc to make better parts for an upgrade of it's construction from raw alluminium plate etc.
As for me,well im just trying to find out what i need to convert cetina file or a tina pcb file to a etch resist pattern on a brass or pcb substrate,how and what software to use,pc to stepper motors.

Extruded alluminium has many useful profiles and ens blocks to suit for fixing together,i make guitar amps,and one material used in cabinet construction is birch ply,it is very stable,with no voids,if coated with shellac it with not soak moisture,keeping a good flat and stiff surface,cutting spindle size will be a guide to how robust the machine need to be,dremels have been used ,and so need less bulk to support the mass and back lash from cutting,another material which will machine easy is plastic chopping boards,not the 6mm stuff from tesco,but commercial 25mm+ poly types,hot or cold resistant no warping unless melted.

As i said software application is my problem,i studied electronics 27 years ago,and used 6502 assembly language to opperate a stepper motor in a simulated washing machine cycle ,my main thing is analog audio,valves to be precise,some digital control circuits,i now find myself needing to learn some c or c++,and need to find the proper path to go from image to physical product via the cutter/etcher.
Wood cutting with a 3 axis mill may well happen or a 2 axis adapted further down the road if all goes well,baby steps,and as always any good advice is appreciated.

16

if its not solid its a waste of time should use arduino mega 2560 with at least 3 stepper drivers maybe 4 then linear rails with machined ball screws driven with steppers of minimum 60 oz/in or better depending what you are cutting. There are so many research factors to consider cheap steppers will slip and not move, the bed needs rails not rods and drive rods/lead screws should be precision ball screws not threaded rods with anti backlash.I have researched all this for a 3d printer currently building that is overkill with the rails I have could be cnc if I get the ball screws add an extra zero or two to that $100 else use a drill and saw