CNC PCB milling

[andrew]

@neverdie I would say, as for a starter kit you should have:

• drill bit set from 0.3mm to 1.2mm, e.g. this, which I already mentioned before. for vias, through hole components you will use a couple from them. I recommend to have at least 2 pack from this. if you make any mistake (e.g. while moving the cnc head to the relative home without properly realigning the z axis after a tool change /yes, it happened with me :)/) then you can easily break a bit. so have a spare set, just in case...
• 0.8mm end mills for slot milling, edge cuts and to mill holes which are bigger than your drill bits (e.g. mounting holes). the previously mentioned set is good, as you have multiple options for different tasks, but I still recommend to have some spare one from the 0.8mm end mill in advance.
• same applies to the carving bit sets. buy one set with multiple size variants (in the given link it is "model 6"), and buy another which just contains 2001 bits (model 2) as these bits will be used the most.
• PCBs. I usually buy mine from local stores, but your linked one seems to be fine. nothing special, single side or double sided FR4 PCBs, based on your needs (size, thickness). I use 1.6mm thick 1oz FR4 boards, others should work as well.

you will/might need double sided adhesive tape, and a sacrificial layer for the cnc, to protect your cnc's bed. I applied a wood board cut for proper bed size for this purpose (see before / after pics below). when you drill holes or mill edges/slots then the drilling/milling tools should go through on your PCB, so there should be a sacrificial layer between your cnc's aluminium bed and the PCB. this layer should be replaced when it become very used.

basically that is it, no rocket science :)

[dbemowsk]

I have been working on gathering parts to build either another 3D printer or CNC machine like this. I think I am sold on a CNC. A question I have on this is what kind of control board does this use? Is it just a standard RAMPS 1.4 board like ones used in 3D printers? Also, is that just a piece of MDF mounted for the build plate? Curious why you didn't just put some T-nuts with clamps on the V-slot plate? Is there an advantage to using the MDF?

[NeverDie]

@dbemowsk said in CNC PCB milling:

Curious why you didn't just put some T-nuts with clamps on the V-slot plate? Is there an advantage to using the MDF?

Without the sacrificial MDF material (where, presumably, MDF is flatter than ordinary wood), then when you drill through the PCB material, wouldn't you also be drilling into the v-slot support metal? i.e. presumably you need some kind of sacrificial layer, and the flatter the better.

[NeverDie]

@dbemowsk said in CNC PCB milling:

A question I have on this is what kind of control board does this use?

One WoodPecker GRBL 0.9 controller and 3 stepper motor drivers:

https://www.aliexpress.com/store/product/Freeshipping-USB-port-cnc-engraving-machine-control-board-3-axis-control-laser-engraving-machine-board-GRBL/424291_32809235879.html?spm=2114.12010615.0.0.6d908f98CJc2us

[andrew]

@dbemowsk that is just a simple laminated MDF, but other materials could also work. the only advantage it has is that it is not a very strong material (when the drill or milling bit go into that) and it is flat.
I used T-nuts at the bottom, but I did not receive clamps, so this is why I drilled the MDF and fixed like this. my original screws were longer than necessary, so later I replaced them with a shorter version (see the picture below), so it is not disturbing now.

you can use clamps, but if you would like to drill or mill as well and not just isolation routing on the top layer, then you need a sacrificial layer between the PCB and the cnc bed. this could be also fixed with the clamps, so it is basically up to you how to solve this.

I went for this solution as it is flat, fix and very stable. for the double sided PCBs I can (and have to) use alignment holes with an additional tool in the holes to position the PCB, then a simple double sided adhesive tape makes the job to fix the PCB.

this cnc comes with the controller board which is mentioned by @NeverDie, it is basically a GRBL compatible board. you can also use different controllers such as arduino based ones, Pi CNC Hat, TinyG and others. it uses Pololu drivers like the RAMPS, but for the RAMPS I'm not sure in the communication protocol.

[dbemowsk]

@neverdie Good point. I hadn't thought about that.

[dbemowsk]

A RAMPS board is much cheaper, but I don't know if that can be used for CNC.

[NeverDie]

@andrew Thanks for all the links. I've ordered everything on your list. Which software will be the first I use? Maybe I can start learning a bit about it while I wait for the deliveries to arrive.

[Vince]

If you are doing only 1 pcb or 2 it is oke to use a cnc milling machine,
i needed a bunch of boards for my home automation project and it took way to long.
Changing bits for engraving/drilling etc and then the costs of the pcb itself.

I went to https://www.itead.cc/open-pcb/pcb-prototyping.html , double sided smaller circuits then with your milling machine and coating , looks like factory pcbs.

it is fun to see the machine working though, made some timelapse videos.
click for the video

[andrew]

@neverdie cool, you will have a nice Christmas then :)

I guess you have experience with EDA tools, such as KiCAD or Eagle. this should be the first point. you should export your PCB related gerber and excellon files (top and bottom copper layers, edge cuts) from the given EDA software, then flatcam is the next one.

in flatcam you have to import the exported files and do all of the necessary preparation work, to create the necessary G codes for every tasks, including isolation routing, milling and drilling.
this will be your main tool, so discover it as much as possible, including the double sided pcb handling part. most of the manual preparation happens here. maybe this tool is the most important in the whole process.

after this, you just have to use a G code sender tool which will control the CNC based on the G code, but this is the easy part. you need a CNC for that, so let's get back to this once you have a working setup. maybe in the meantime you can check e.g. bCNC's and chilipeppr's general howtos.

without a working cnc you can also visualise and simulate the G code, e.g. with CAMotics.

[NeverDie]

@vince I think it's meant for prototyping, not production. At least for that purpose, the reduction in turnaround time should be huge. If, instead, you send everything to the fab at every step, then you need the patience of a saint to iteratively evolve a PCB design.

[Yveaux]

@andrew you wrote you sourced your cnc from the EU. Could you share where you bought it?

[andrew]

@yveaux I bought mine from "rattmotor" seller on ebay (https://www.ebay.com/usr/rattmmotor), but I basically just limited the item location filter to Europe when I searched for cnc2418 on ebay, then I made my choice based on the price and seller ratings.

[NeverDie]

@yveaux Even Amazon.com sells them. Some even have 1-day Prime shipping, so you could have one tomorrow if you wanted.

[Yveaux]

@neverdie Amazon still doesn't ship to the Netherlands and all eBay sellers seem to ship from China...

[andrew]

@yveaux search for "cnc 2418" with space separated, then you can find some one from Germany.

[Yveaux]

@andrew ok, I'll give it another try, but suggested rattmotor also seems to ship from China (despite all the American flags in the pictures...)

[andrew]

@yveaux they had items from China and from EU warehouse as well. with the search I mentioned you can find product like this or this

[Yveaux]

@andrew ok, thanks! It was probably the mobile searching then that hid them.
Probably better not having the link though... Must resist to click....

[NeverDie]

@yveaux If you do a fair amount of PCB prototyping, then it pays for itself pretty rapidly (as compared to using a Fab that is).