Introduction: $20 CNC Machine

I got inspired for this instructable when I viewed the Easy To Build Stepper Controller

instructable .When I read the instructable I knew I could make a decent looking and functioning cnc machine for under 20 dollars with a recycled twist, Not to mention I did this in under a week.

I expect you to have basic knowledge on power tools and hand tools
and of course this instructable requires you to have a rotary tool such as a dremel.
Even if you don't have knowledge on power tools or hand tools I advise you to try this instructable because you will learn a lot about hand and power tools and you can build this for less then 20 dollars
so if you mess up it's no biggie and it would not cost to much to replace a part.

Let's Build!

Update 02/01/10

{Hi everyone just thought I would give you an update on this instructable since Ive been getting
a lot of emails and messages and such.

I'm getting really close to completing the electronics for the CNC,
as stated in a comment the steppers I found in the printer were bi-polar stepper motors which the circuit
would cost quite a bit more if you went this route. If you were lucky to find some Unipolar stepper motors
then you could build the electronics for under 3 bucks however unipolar motors have less torque. I will be selling CNC kits soon and they will be of better build quality as well as a cheap price tag because I know how it is to be on a budget and not have the tools I need to create simple things and even complex things and this world needs more DIY builders.

The CNC kits will be available roughly 1 to 2 weeks after the electronics Instructable has been released
their will actually be a video showing this CNC working when the electronics Instructable is completed} 

Step 1: Find Recycled Material

Now this is the most enjoyable part of building the cnc machine
which is trying to find garbage that people want to throw away.

Here's what you need to locate

Flat bed scanner

Old printer

These two items are going to have your juicy stepper motors and the
beautiful harden steel rods, that's not the only thing you can get out of these green machines.

You will find gears, bushings, cold cathodes, capacitors, buttons, parallel ports and there is
so much more.

Step 2: Tools

Now I tried to build this with the bare necessities so I could show you that it is possible to
make a cnc machine with very little.

Required Tools:


Screw drivers

Tap and Die set

Rotary tool

Hack saw

Vise or some form of clamping device


Drill bits


Center punch

Recommended Tools:

Band saw

Table saw


Bench grinder

Bolt cutters

Step 3: Linear Slides of Fun

The center core of your cnc machine is your tables
so read carefully and follow the instructable.

Required materials

Quantity Type Cost

4 2"x6"x1/2" Expanded PVC 2.00

2 2"x4"x1/2" Expanded PVC 1.00

2 10" 3/8" Aluminum rod 0.75

2 12" 3/8 Aluminum rod 0.75

2 8" 3/8" Aluminum rod 0.50

1 11 1/4" 5/8"-24 threaded rod 1.00

1 9 1/4" 5/8"-24 threaded rod 0.75

1 7 1/4" 5/8"-24 threaded rod 0.50

Now this is just the run down of everything
I of course cut everything up, you can purchase everything you see here from your local
hardware store and plastic store for really cheap.

First step

Stack 2 of the expanded pvc pieces that are the same size and drill a whole in the center
and two holes each three quarters of an inch from the edge from the center line.

Now cut your aluminum rods to size and stick them through,
now you should have a comparable piece down below

Repeat for all Axis

Step 4: X,Y,Z Tables for Your Brunch

Alright now here comes the most time consuming part
making the tables for the slides but once they are made it really feels like the project
is taking off.

Required Materials

Quantity Type Cost

1 6"x12"x1/4" Acrylic sheet Scrap

1 6"x10"1/4" Acrylic sheet Scrap

1 5 1/2"x5"x1/4" Acrylic sheet Scrap

15 1 1/2"x1 3/4"x1/2" Acrylic sheet Scrap

Now what you are going to want to do is stack 4 pieces of the 1 1/2"x1 3/4"x1/2"
and drill dead center with a 3/8 drill bit

After you have done so feed 2 pieces on each rod
and line them up and place your sheet on top and flip it over now glue.

Repeat for each axis

For your Y axis

now would be a good time to drill your holes so you can mount things you wish to cut.

Step 5: Motor Mount Time

Now depending on where you get your motor from
they are all going to be different so they will require special mounts

I recommend printer stepper motors because they are easy to mount but scanner steppers motors will work just fine.

Now in step three you should have drilled the motor hole and now all you have to do is mount it in

The coupler that attaches from your stepper to your threaded rod is going to be different based on
stepper you have.

I made one out of aluminum but you can make one out of plastic just as long as it is wide enough.

All you have to do is drill in the center of a little piece of rod
to the size of the stepper then on the other side drill 5/16 for the threaded rod.
After that tap the 5/16 side
And glue

Step 6: Thread Me Please

Now once you have made your coupler it's time
to attach the threaded rod and glue a threaded coupler to one of the 1 1/2"x1 3/4"x1/2" square blocks

You have to make sure that the center on the threaded coupler matches the center of the threaded rod.

After you should get something like down below

Required Materials

Quantity Type Cost

3 5/8"-24x1" threaded coupler 0.60

Repeat for each axis

Step 7: Gluing Time

So now you should have all three axis completed and now it's time to line them up and glue.

The base I used was a 20"x12"x1/4" piece of white acrylic I found at the plastic store

You could use smaller but I wouldn't recommend it

Once you have found a base, glue your x axis to it and then your y axis to your x axis acrylic top,
then you should have something like down below.

use acrylic glue
for this step

it will glue expanded pvc as well if your wondering

After that Glue your z axis to a piece of
8"x4"x1/4" acrylic sheet.

Required materials:

Quantity Type Cost

1 20"x12"x1/4" Acrylic sheet scrap

1 8"x4"x1/4" Acrylic sheet scrap

Step 8: Where's the Z Axis :(

Don't worry I didn't forget about that

Moving along

Now we want to add a mount for are rotary tool to the acrylic sheet on the z axis

I used a pipe holder and a screw clamp, you can buy both these items at a local hardware store for really cheap.

You have to cut a little lip to attach to the acrylic sheet because the pipe mount isn't going to be flat once you slide the rotary tool in because it expands.

Place the pipe mount on top of the acrylic lip and glue.

Required Materials

Quantity Type Cost

1 Pipe mount 0.40

1 Screw clamp Free

Step 9: A Piece From the Heaven's

Now that you made your z axis rotary mount it's time to set up
the posts and the acrylic sheet that connects them.

You need a square hole in the center of the 10"x16"x5/16" acrylic sheet to feed your z axis through

After you have cut that out it's time to attach a thick piece of a acrylic
to support the z axis on.

After you have done that you should attach you z axis to it and make sure the acrylic piece is sticking out at least 1/16" off the edge so you can have a flat side.

Required materials:

Quantity Type Cost

1 10"x16"x5/16" Acrylic Sheet Scrap

1 1 1/2"x5"x1" Acrylic Sheet Scrap
(aka thick piece)

Step 10: Tall Posts Oh My!

Now it's time to glue
the 1 1/2"x16"x1" posts to the z axis acrylic top
and then after your done with that, you then glue it to the base.

Required Materials:

Quantity Type Cost

4 1 1/2"x16"x1" Scrap

Step 11: Are We Done Yet!

The answer is no but we do happen to be mechanical done
now because of the short amount of time I had I could not add the electronics part to this instructable,
so I am going dedicate an entire instructable just to the electronics part some time this week as well as a video.

So turn that frown upside down

Word of advise this is quite a bit of work even though it may not look like it
so by the time you have this finished the electronics instructable will be beyond finished.

I will most likely add it on Tuesday or Wednesday of this week.

Part list:

Quantity Type Cost

4 2"x6"x1/2" Expanded PVC 2.00

2 2"x4"x1/2" Expanded PVC 1.00

2 10" 3/8" Aluminum rod 0.75

2 12" 3/8 Aluminum rod 0.75

2 8" 3/8" Aluminum rod 0.50

1 11 1/4" 5/8"-40 threaded rod 1.00

1 9 1/4" 5/8"-40 threaded rod 0.50

1 7 1/4" 5/8"-40 threaded rod 0.25

1 6"x12"x1/4" Acrylic sheet Scrap

1 6"x10"1/4" Acrylic sheet Scrap

1 5 1/2"x5"x1/4" Acrylic sheet Scrap

15 1 1/2"x1 3/4"x1/2" Acrylic sheet Scrap

3 5/8"-24x1" threaded coupler 0.60

1 20"x12"x1/4" Acrylic sheet scrap

1 8"x4"x1/4" Acrylic sheet scrap

1 Pipe mount 0.40

1 Screw clamp Free

4 1 1/2"x16"x1" Scrap

? Scrap from Tap Plastics 12.00

Total= 19.50

I got all my plastic from tap plastics scrap bin and I got the rest of the pieces from home depot
and a local metal supply shop.

Step 12: Recommendations

Now the stepper motors you find in a printer would do just fine
but after a while I would highly recommend to upgrade to some bigger stepper motors.

As for the expanded pvc I would replace that with Acrylic but do to the fact that I had a budget and the short amount of time I had no choice but to go with expanded pvc but I would really recommend you use acrylic.

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