PCB CNC Milling Using FreeCAD

[BlackCoffee]

I use CopperCAM to Mill my PCB’s but, I have used other’s and (IMO) nothing compares as favorably to CopperCAM.

However, it’s worth noting that FreeCAD’s Path Workbench has improved significantly over time and it works rather well for Milling PCB’s.

To keep the Video file small, I show only a Visualization segment of the PCB being milled in FreeCAD - you can see the other lines for milling the Holes and Shape (I did not bother to create a larger Stock to cut from nor did I set the THT holes…).

Using the Path Workbench (and FreeCAD) does require some learning but, you can see it works well and, though not shown, is it’s variety of Gcode export formats…

I used KSU StepUp to load the PCB, Pad/Traces then, flipped the PCB Axis to get Traces/Pads on Top…

[teletypeguy]

OK, you are really prompting me to dig into freecad more. What machine do you use for milling? Does the path tool also have a z-axis for general 3d cnc or edm machines?

[BlackCoffee]

@teletypeguy

What machine do you use for milling? Does the path tool also have a z-axis for general 3d cnc or edm machines?

Mill Machine - for PCB and light-weight CNC machining, I use a MicroProto. In fact, since retiring 25 yrs ago, I sold all my large machines.
But, to more responsibly, recommend low-Cost Mill for PCB’s, I bought a $120 CNC mill. It’s good enough for PCB and light-weight milling and education.

Link to my Show-And-Tell of the $120 CNC Mill machine.

FreeCAD (FC):
• Important to know - like many Software packages (including Kicad), FC embeds a variety of Tools/Apps. FC calls them ‘Workbenches’ WB

• Some WB’s play well with others. Some don’t (but, getting better)
Thus, a proficient User will need to know what WB’s do what. And, to make it a pleasurable, efficient Tool, User should know how to Create/Tweak Toolbars that add Icons/tools from other WB’s (to reduce going jumping from one WB to another).

• Yes, the Path WB does 3D-Contouring to fully shape whatever you can model

• The “Part Design” WB (as opposed to the “Part” WB) is most like SolidWorks/ProE…etc and a SolidWorks/etc user will quickly come up to speed (many similarities but with Different Names of things. Example: SW uses the word ‘Extrude’, FC calls it ‘Padding’).

Creating Text on a Model is done properly in the “Draft” WB.
Watch my tutorial on making a Capacitor’s Text (starts at ≈ 4 minutes). As with most other things, there are other ways of doing it…

Here are some of my Vid’s to give you some ideas… of Use and Similarity…

FreeCAD for Kicad PCB Shape And Cutouts includes making a 2D-Drawing using the TechDraw WB

Making A Cable Assembly & Kicad Footprint shows sweeping a Path for a Cable/Connector

Re: “edm”, I don’t know (haven’t explored it in FC. CopperCAM does have Laser Tool definition panel but, that too, I don’t use…

…etc

[teletypeguy]

Peeked at some of your videos – makes me want to carve out some time to learn freecad now.

Off-topic question: I am not into telescopes but your azimuth/elevation gizmos look interesting. I’ve always wanted to make a drive mechanism for a 2m/70cm yagi antenna for tracking amateur radio satellites and the ISS. I see you were using some vex encoder goodies – never got into vex stuff but spent a few years in frc with my son, and recall similar shaft encoders. Are there any diy telescope drives that would be applicable? I was thinking steppers and belts, but a motor and an encoder with decent resolution would probably work well.

[BlackCoffee]

I’ve made handful’s of these gizmos and have tested over 20 different encoders for them - I could write a Dissertation on it but will just say the following:

VEX are low PPR (Pulses Per Revolution) and while they may be accurate enough for low resolution (toys, robots…etc, perhaps for a crude Antenna, too) I would go with something like these (I use them/similar brands) exclusively now. But, there are many other’s these days to consider… Stick with Optical Encoders!

In the end, 'Accuracy’ is only as accurate as the placement on the ground and alignment to reference stars/object. I designed Digital Levels to aid adjusting scopes.

Getting the current position:
It’s about the Gears, Encoder’s PPR and your code. You can get the Gearing and PPR relationship for designing/coding from my first DSC video

Driving the Antenna to positions:
You don’t need a ‘Closed Loop’ system. An ‘Open Loop’ system (without position feedback) is perfect if you’ve tested its accuracy and can live with results.
You could ‘test’ for Radio-Signal strength and use it’s value in calculating Feedback in a Closed or modified Open loop system.

Either way (Closed or Open), you want to get the Encoder’s position and use it in relationship to driving the Motor.

Steppers would be my choice - they eliminate having typical ‘Motor’ related concerns. Servo Motors are also doable (and, I’ve tweaked some to make them fully rotational).

I don’t follow the product market so, I don’t know what’s out there but, many Astronomy sites (especially those geared toward Astrophotography) may be useful.
ADDED: Google for “Homemade Radio Telescope”… you may find great ideas…

[BlackCoffee]

In follow-up on this rainy-day, I posted a (perhaps) useful full video on YouTube with the following Content

[teletypeguy]

That’s interesting Bruce. A couple of questions: What is the smallest endmill bit you use without breakage problems (well, on 1.6mm fr4 in particular)? Also, on the pocket cutout, it looks like a little bit was not cut on two internal sides – can you enforce an internal perimeter trim cut as a final clean up or are all the path decisions made by the program?

[BlackCoffee]

I spent countless amounts of time Testing various Bit’s (materials, sizes, speeds, feeds…) and once dialing-in what I think is the Best, No More broken Bits! Haven’t broke a Bit is several years.

For All my PCB’s (FR4 and Poly)
Endmil Bit for making Traces:
0.7mm
Speed = 160 mm/Min
Depth of Cut = 0.4 mm

Endmill Bit for Contouring PCB shape:
1/8inch (3.175mm)
Speed = 150 mm/min
Depth of Cut = 0.5 mm

The Pocket - mentioned in video that I wasn’t going to add video time by doing the Finish Milling. But, Not a problem to do it - just need to set the parameters and, for the Heart, also change Bit to ‘Ballend’ and set the Stepover and depth of cut… (to reduce sanding).

None of the Decisions are made by the machine/FreeCad… I made all the decisions.
Easy to ‘enforce’ just about every aspect… so, Cleanup/Finishing passes are easily done (and, don’t be fooled by thinking those unfinished aspects are as ugly as they look - the actual Part is only 12mm diam so, you’re looking at extremely-blown-up photo…
CORRECTION: 8mm dia and pocket is less than 5mm (photo attached)

I made a couple of Archtop (Jazz) guitars and Milled the Bridge’s, Tailpiece’s and Shaped the Head… All wood…

I also Milled the ‘F-holes’… and Pickguard (both pickguard and tailpiece have Inlaid Rosewood - thus, needed to first make the Pockets…

Test Panel for Milling - last screenshot

[teletypeguy]

Thanks for the milling details. Nice work on the guitars! The inlays are a beautiful touch. And it look like a dozen coats of hand-rubbed tung oil

[PaulF8080]

It’s not just you, but why are people calling edge cuts milling. An end mill has a Z depth. A through hole router bit is used.

[BlackCoffee]

@PaulF8080

calling edge cuts milling

If I understand you correctly, then, I’m not seeing anyone referring to Edge-Cuts as “Milling” (or, Milling Cuts, unless referring to the Verb ‘Milling’ as in “I’m milling cuts on my PCB”).

Kicad Users know/learn that the PCB Shape and it’s related Holes (usually NPTH), Cutouts…etc are in Kicad’s Layer called “Edge.Cuts” and that the shape of the PCB/etc in that layer can be achieved by various means, including Milling.

I Mill my PCB’s.