1. Ben MacLeod – Eng. Phys. Project lab - Jan 30 2013
How to Run the PCB mill
Ben MacLeod – Eng. Phys. Project lab - Jan

2. DIY PCB’s can be a pain Have you considered outsourcing the job?
Cheap
Relatively fast
You can even have components mounted for you
See, for example:
PHAS E-LAB (electronics shop) may also be able to do a board for you?

3. PCB fabrication Workflow
Eagle/Altium
Design PCB
Export gerber files Eg: *.cmp,*.sol,*.drd etc..
CIRCUITCAM (CAM preproccesor software)
Import gerber files from CAD
Process gerber files into *.LMD file: contour, rubout, insulate (define tools sizes)
BOARDMASTER (pcb mill controller)
Import *.LMD file
Drill, Set tool height, Mill, Flip, set tool height, Re-index XY, Mill, Cutout
Assemble PCB
Tin,Solder Vias,Solder components etc..

4. PCB design for manufacturability
Big traces make things easier to solder (and big gaps between is key also)
Small footprint boards are easier to mill
Due to poor surface flatness
Alignment marks are useful for re-aligning after flipping the PCB (extra holes or crosses)
Check that the mill has the neccesary tools for your design
Eg: -If you want a 0.9mm hole in your PCB, check that we have that drill size (we don’t!)
Rubout helps when you have closely spaced components (e.g. surface mounts)

5. CAM files You need several cam files to describe your board:
What is described
Altium output file
Eagle Output file
Gets encoded into Circuit Cam layer named
Board outline
*.GKO
(Gerber keep out)
*.otl
(outline)
BoardOutline
Top layer
*.GTL
(Gerber Top Layer)
*.cmp
(components)
TopLayer
Bottom layer
*.GBL
(Gerber Bottom Layer)
*.sol
(solder)
BottomLayer
Drill pattern
*.txt (NC drill)
*.drd
(drill data?)
DrillPlated

6. Exporting from altium Open your pcb layour (*.pcbdoc)
Make routing data (*.GTL, *.GBL, *.GKO)
File > Fabrication Outputs > Gerber files
Select appropriate layers
Settings?
Export
Make drill data
File > Fabrication Outputs > NC drill files ok

7. Exporting from eagle Taken from Tinny Lai’s instructions, 2008
1. Select File > CAM Processor.
2. Inside the CAM Processor Window, select File > Open > Job…
3. Open the gerb274x.cam file.
4. Under the “Component Side” tab, make sure the “Top”, “Pads”, and “Vias” layers are selected.
This will be generating the .cmp file.  
5. Under the “Solder Side” tab, make sure the “Bottom”, “Pads, and “Vias” layers are selected and
that the “Mirror” checkbox under Style is NOT checked. This will be generating the .sol file.  
6. If there is not a tab for “Board Outline”, click the “Add” button while on the components or
solder tabs to create a copy. Rename the section to “Board Outline” and the file extension to
.otl. Deselect all the layers except the “Dimensions” layer. This will be generating the .otl file.
7. Click “Process Job” and these 3 files should be generated in your project directory.  
8. Select File > Open > Job…  
9. Open the excellon.cam file.  
10. Make sure that the “Drills” and “Holes” layers are selected. This will generate the .drd drill data
file.  
11. Close the CAM Processor window.  
12. Type run drillcfg on the Eagle command line.  
13. Select mm and save the .drl to you target directory.  
14. Transfer these files to the Milling Machine computer: .cmp, .sol, .otl, .drd, .drl
Taken from Tinny Lai’s instructions, 2008

8. CIRCUITCAM I File > New > Eagle.cat File > Import
Highlight and open your 4 files
Match them, 1 by 1 to the appropriate layer
Eg *.GBL  BottomLayer
Altium output file
Eagle Output file
Gets encoded into
Circuit Cam layer
named
*.GKO
(Gerber keep out)
*.otl
(outline)
BoardOutline
*.GTL
(Gerber Top Layer)
*.cmp
(components)
TopLayer
*.GBL
(Gerber Bottom Layer)
*.sol
(solder)
BottomLayer
*.txt (NC drill)
*.drd
(drill data?)
DrillPlated

9. CIRCUITCAM II Edit > Contour Routing > Run
Insert > Rubout Area
select the layers and areas where you want to rub out (remove) the copper.
Edit > Insulate.
Select the your tools/cut widths
If your not sure, use {.2mm, 1.0mm, 3.0mm as below)
Don’t worry about small it can be the same as standard or blank
click 'Run' (NOT ok) for both the Top and Bottom Layer.
File > Export > LPKF > LPKFCircuitBoardPlotter to export the .LMD file to be used in Board Master.
Taken from Tinny Lai’s instructions, 2008

10. BOARDMASTER/ MILL OPERATION overview
Load *.LMD file in boardmaster
Mount your blank PCB
Designate an area on the PCB for your board footprint
Drill holes
Set universal cutter height/thickness
Mill 1st face
Flip, reset cutter height, re-index cutter (XY)
Mill 2nd face
Cut out board

11. BOARDMASTER file setup
File > Import > LMD/LPR to import your .LMD file.
Click the button with an arrow point in each of the 4 directions and pick a place on the machine area that will fit your PCB.
The machine head will move to this position.
The individual arrow buttons can also be used to make the machine head bit by bit.
Find the button with two rectangles translated diagonally
Should display 'Enables the moving of instance of project by mouse' when hovering over the button
Select this button and move your PCB layout to the machine head cursor.
Can do this alternatively with edit>placement
Taken from Tinny Lai’s instructions, 2008

12. Mounting blank PCB onto the mill bed
GOAL : Get the PCB as FLAT AS POSSIBLE
If PCB is not flat, tool height z changes as f(x,y)
Since milling tool is conical, cut width changes as f(z)
This is bad! Want constant cut width everywhere
How:
Vacuum clean rigorously, wipe down PCB
Bits of copper, dust, PCB material prevent PCB from sitting flat
align PCB hole & slot with pins on mill-bed
Put heavy weights on PCB
Tape edges of PCB down VERY firmly
Remove the weights
Can check flatness by doing trial cuts on opposite side of board
If they are the approximately the same width then board is mounted properly (flat)
If they are significantly different, the board is mounted improperly (not co-planar with mill bed)  try again
Dirt/particle/Debris
GOOD
BAD
PCB
Mill Bed

13. Drilling the holes Select Layer Markingdrills Select Layer Drillplated
Click All+
Start
This adds small pilot divots to the board using the universal router tool
Select Layer Drillplated
Actually drills the holes
If the right drill isn’t in the toolbox, you will need to put it there
See next slide for details

14. Understanding the toolbox
The mill doesn’t really know what tool the chuck is holding
All it knows is which tool rack (toolbox) position it picked up the tool from
If you need a certain tool or drill size that is not all ready in the tool rack you have to replace a tool in the rack with the tool you want and then tell the machine what you have done
Be careful to get the numbers right otherwise the machine could try to put a tool into an allready occupied spot and something could break!!!
If you don’t have the exact drill size (say you need a 0.9mm drill – which we didn’t have as of Jan 30, 2013) you may be able to getting away with lying to the machine about what tool you’ve given it (by, for example putting a 0.8mm drill in tool slot #3 but telling the machine it’s a 0.9mm) as long as the difference is small enough that your PCB still works
-add a picture of the toolbox

15. Milling the bottom Select layer MillingBottom Click All+ Click Start
Remember to stop and adjust tool height / cut thickness before the cutting run
See next 2 slides for more details on this step

16. LPKF PART # 101010 -Universal Milling Tool
0.0955” (2.45mm) – just for reference, not an important dimension
0.029” (0.75mm) – important dimension (max cut width)
90 degrees - important angle (gives relation ship of cut width to tool height)
-add photo of drill

17. Understanding and getting a feel for cut thickness
0.029” (0.75mm)
90 degrees
WAY TOO THICK (T=0.029”)
TOO THICK (0.008”<T<0.029”)
-add photos of what a good/bad cut thickness looks like
T= 0.008” (0.2mm)
TOO NARROW T<0.008”)
JUST RIGHT (T~0.008”)

18. Adjusting the cut thickness (tool height)
Do a manual cut somewhere near to but off the your board
Use microscope to measure cut width
PEAK microscope has grid in 1/1000’s of an inch
Can turn the measuring grid by turning the eyepiece
Fine-adjust tool z-height until cut width is as you specified in CIRCUITCAM (0.2mm=0.008” is the default cut thickness)
See the excel calculator on the PCB mill controller desktop
The knurled fine-adjustment nut changes the tool height ~4 microns per click (0.004 mm = ” travel per click)
A full rotation of the knurled nut changes the tool height ~0.5mm (e.g. ~125 clicks per full rotation)
Turning the wheel clockwise (looking from above) moves the tool down (towards the surface)
for the 90 degree Universal cutter tool the cut width changes by twice the change in tool height
if you bring the tool up by 4 microns the cut width decreses by 8 microns
0.001” change in cut thickness  ” change in tool height  ~3 clicks
The adjustment mechanism is finicky (either too loose and doesn’t click or too tight and impossible to turn)
to get it to click loosen the screw 1-2 turns back then gently tighten it back in until you just feel it contact. Then back it off ~1/4 of a turn
Take cuts on either side of your board to ensure that board is flat (as discussed in the mounting section) and that cut width is consistent

19. Milling the top Layer MillingTop
Flip and re-index pcb (see next slide)
All+
Start
Adjust tool height (flipping the board will have thrown off your height setting)

20. Flipping and re-indexing the board
When you flip the board over BOARDMASTER moves the CAM pattern (approximately) to where it needs to be to keep machining BUT NOT EXACTLY
To properly mill the 2nd side of your borad you need to make some minor adjustments to the alignment using the edit>place command and the camera (probably need ~0.001” accuracy)
BOARDMASTER has an automated way of doing this using reference holes called “Fiducials” but this hasn’t been figured out yet

21. Cutting out the board Layer BoardOutline All+ Start
Do you want to adjust tool?  Yes
Do a test cut to make sure the 2mm contour mill is cutting all the way through the board
After verifying the mill height, press start again and cut out the board!
You can use some little pliers to cut out the small tabs that hold the board in place after this step

22. You have milled your PCB!

23. Warnings, Tips & Troubleshooting
Cut thickness keeps changing?
Board is not mounted co-planar to mill bed
Be very careful in BOARDMASTER
If you change layers (scrollwheel can do it  )part way through milling a layer you will lose all your progress
Use manual controls to do test cuts (e.g. after flipping)
Machine spatial resolution is not quite as good as it is specified (only matters for tiny traces)
See manual p.88 for more tips

24. Assembly Dip your PCB in liquid tin
Looks cool (silver!)
makes soldering easier?
Protects from oxidation?
Alternatively, spray with Solderlac surface treatment
Similar results to liquid tin? (haven’t tried this)
A good trick when you need to solder lots of vias
tape a piece of foam onto one side of the PCB then jam in a bunch of overlong wires
Solder the wires on the exposed side (foam holds them nicely!)
Flip, solder other side, snip all wires

25. Some people who have run the PCB mill more than once (as of Jan 2013)
Alison Vrielink
Theo Pacson
Yegor Rabets
Ben MacLeod
See Jon for others

26. Suggested improvement to this document
A more specific, detailed description of how to re-index the XY position of the cutter head to the PCB after flipping the board
Ideally using BOARDMASTER’s automated “fiducials” technique
Alternatively manually, with an associated excel calculator to make it easier and less headache inducing
Add more photos / screen captures / videos that illustrate the actual operation of the setup. Specifically:
Important menus (eg: Circuitcam menus, Boardmaster toolbox menu,Boardmaster placement menu, etc…)
An annotated picture of a range of cut thicknesses to give people a feel for what they want
The height adjustment mechanism
Generally correct and improve the slides, adding details, troubleshooting tips and tricks for doing things more easily (e.g. getting the height adjustment to click )