Easy and Cheap PCB Milling

I write this guide because I think It's helpful starter tutorial to milling PCB in a very simple way and low budget.

You can find complete and updated project here https://www.mischianti.org/category/tutorial/milling-pcb-tutorial/

If you have some passion for homemade things you must build a router.

To build It you need arduino an old scanner and an old printer.

I write old in bold because new device sometime haven't a stepper motor but brush motor with feedback device.

Than If you have at home a dremel like It's perfect to complete your CNC.

My CNC is that (a mix of drawer guides, epson gt-8700 and Lexmark x642e all completed with plexyglass).

Finally I upgrade my router:

www.mischianti.org

Component of CNC

• Arduino UNO.
• CNC Shield (eBay).
• DRV8825 (eBay).
• Stepper from Scanner and Printer.
• Relay to activate Dremel (eBay).
• You must create a board to eliminate noise from limit switch.
• I use HC-05 bluetooth to control the CNC because the noise of dremel is very high and I prefer control from another room (eBay) (Explain connection here).

Program/firmware on Arduino

• You can find here the program to upload to arduino (I must change some property of code to use without speed regulator, my dremel is activated or deactivated without PWM).

For the project I select a single side Copper clad plate 1.5mm thin.

eBay

Exists 2 variant one with yellow (laminate) and other white material (Glass Fiber), the second one is better for milling.

It's very cheap bit I buy 10pcs for 3$, and work well.

eBay

A beautiful program to prototype board.

http://fritzing.org/home/

A specified program to create gcode from Gerber file.

http://flatcam.org/

This program is what I like to use to control my CNC but you can use what you want.

http://winder.github.io/ugs_website/

To start we need a project, I like to create a fast prototype board for my IC, and I like to program with ESP01, I like to work with only two wire (so I can use Serial olso), so PCF8574 IC a I/O port expander via i2c protocol is my first prototype board.

The input female pin is GND, VCC, SDA and SCL, the dipswitch-03 is for setting address of i2c.

Then there are 8 female pin for I/O (P0-P7) and a Interrupt pin near SDA SCL pin.

You can find library to use in a simple manner the IC here and the instructable here.

For first you must create your prototype on breadboard.

As you can see the only difference from a "normal prototype board" is that I add a female pin.

I add that because so I have that pins to the PCB schema.

If you want you can create a schema for better comprehension, but It's not needed.

Than in the third tab you have a scrambled PCB and here we must work.

Positioning is very simple, so I add only some advice.

For first select a gray PCB and in the right panel select one layer PCB.

Than start to positioning element over the PCB.

Than connect element, when you have a overlap you can use a jumper element, you can find It at the end of core parts with some other useful instrument for create PCB.

I need to connect 2 elements but 2 wire is in the middle so you can use a jumper wire to doing that.

Sometime I don't use jumper wire because I like to create hole bigger than normal.

You can specify size, when I can I create 0.8 0.8 hole (for bigger hole ring).

The blank PCB that I buy is 7cm x 5cm.

To have a better milling surface I prefer use few 45° angle copper wire and I'm going to use a bigger surface with minimal waste so I select a sub-multiple dimensions like 1/2 of the size 3.5cm x 5cm.

When you use few 45° angle you can create a thick copper wire.

Bigger copper wire is more safe when you are going to route PCB.

So select copper wire and "extra thick" on panel.

In this project I need a dipswitch 03 but in Fritzing you have 02 and 08, if you want you can create the component or you can overlap 2 of that to create a single dipswitch 03.

If you want add some text on PCB you can use a text instrument.

Now we create a single side PCB so to write something like second image.

You must select silkscreen bottom, and to have a good readability I think you must set 4mm text height.

At the end when you connect all elements and write what you want.

The typical result is in the Image.

In Fritzing we can export the gerber file from the menu File-->Export-->for Production-->Extended Gerber.

Select a folder and go.

The name of the generated file is quite readable.

First I set some default value on my FlatCam.

I set 0.57 for tool dia[meter] because it is the max tool size without too many overlaps.

For Excellon (drill information), I set it to 1.5mm because this is the thickness of the copper clad that I buy.

Paint area I set overlap (0.01) and margin (0.1) very low to create small letter.

Border put 0.1 to margin, other value is reccomended.

You must import in FlatCam so:

File --> Open Gerber

• copperBottom.gbl
• silkBottom.gbo
• contour.gm1

File --> Open Excellon

• drill.txt

The last one is drilling but Excellon is already geometry.

I don't want to change the bit; I've use the same bit all along and a punching tool to enlarge the smallest part of the V hole. Or if can set low dept and finish hole with a 0.75mm bit.

I also use the punching tool to remove the copper connections that aren't removed by the CNC.

• Select drill.txt on the screen where there is the list of bit sizes, click and select all (Ctrl+a).
• Then go to generate CNC Job.
• Cut Z is the dept of the hole, I set It to -1.5mm the height of copper clad.

Tool dia to 0.57 as usual, and set splindle speed if needed (I use dremel with costant speed).

Now select "Combo" element (generated from the joint geometry of silkBottom) then Create CNC Job.

Lastly, select contour.gm1_cutout.

Here I prefer to generate a cut of 0.5mm dept, then I cut to the line with tin scissors, so I set 0.5 of final dept and 0.05 for pass.

From FlatCam select one to one the "*_cnc" file and "Export G-Code".

I use to send command to CNC UGS, It's very simple and beautiful.

The common cutting order is:

• copperBottom
• label
• drill
• border

Here a simulation of Universal GCode Sender.

I use biadesive to hold copper clad to the surface.

For this part I use a photo of other project that I have directly available.

After positioning Zero coordinate, start routing.

For this part I use a photo of other project that I have directly available.

Finish copper bottom routing.

When finish the result is quite ugly.

For this part I use a photo of other project that I have directly available.

With sand paper PCB take form.

Then cut border with scissor.

For this part I use a photo of other project that I have directly available.

Now we have our first view of PCB

In a full PCB copper ring thickness is quite thin, but no problem to solder It.

The result It's ok.

Link to library here.

Link to library here.

Very usefully to use all 4 pin of ESP01, and to manage external power supply.

This version is my smallest size of the board, with very thin copper wire at 45° curves.

Link to library here.