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Mill, laser or pen ?

someguy
Wed, 04 Feb 2015 16:19:26 GMT

I need to produce small numbers of prototype PCBs from time to time. 2 to 4 boards, that sort of thing, usually just for testing purposes. I'm looking for some advice from this community. I want to use flatcam and a CNC machine to do it in house. I think I have 3 options. Mill the boards, use a laser to activate an etch resist or use a pen to draw etch resist on the board. I love the accuracy of the laser approach, but the board then needs to be developed before it is etched. I think I dislike milling because of the noise and dust, but I like the fact that I can then use the mill to drill. I love that it skips the etch step. I like the pen because its direct, ie board straight to etch, but I've never seen a pen system that reliably makes tiny board features, ie thin traces and isn't fiddly. I have a Roland DXY 980 flat bed plotter that I can use for the laser and pen approaches. Its a stepper machine. I'll replace the electronics with a Smoothie controller. I've built CNC machines before. If I go for the mill approach, I'll probably buy one of the Ch inese 2030 mini table top mills and put Smoothie on it. Total cost will be about $600. No reason why I couldn't put a laser on it too, but it wouldn't be nearly as fast as the Roland. Advice, tips, suggestions ? PS: I'd love to have a way to apply a solder mask and/or text to a board. Would greatly improve the value of the boards, making them easier to work with.

someguy
Wed, 04 Feb 2015 16:51:19 GMT

Here is a video of the laser method. https://www.youtube.com/watch?v=4SNkzoOvoD8 Here is a video of the direct pen method. https://www.youtube.com/watch?v=rLQajSRnELc

someguy
Wed, 04 Feb 2015 20:28:32 GMT

I just watched this video (https://www.youtube.com/watch?v=na9-USi_hZQ) and I'm pretty much sold on getting a 3020 CNC router and routering my boards. Advantages - single step process, ie no developing or etching steps - don't have to deal with etchant or developer chemicals - it drills the holes (accurately) - it routers the board edges and drills mounting holes - it works with any bare board - it seems like a robust process - can leave untouched area on the board and then add to the circuit later. This is a big plus when prototyping because it saves having to redo the entire first part of the circuit. The dust isn't too bad. The noise isn't too bad either. Its pretty fast as well, overall. A laser might "print" the board faster, but then you have to develop it, etch it and drill it.

jpcaram
Thu, 05 Feb 2015 22:23:48 GMT

Milling is a single-step process. No chemicals. You can easily attach a vacuum hose to the side of the spindle. You will certainly get higher resolution with the laser though... The 3020 is of very low quality as far as I know. I have a 7x7 ZenToolworks, which is made of rigid PVC, but the moving parts are of high quality. Specially the leadscrew with anti-backlash nut. It's also around US $700.

someguy
Thu, 05 Feb 2015 22:44:23 GMT

I'm actually going to buy a 3040 with ballscrews. Its a bit more money, but probably worth it. I will only use this machine for light work - PCBs, a big of wood, etc. I have a full sized lathe (CNC'd) and milling machine (about to be CNC'd) for doing heavier work. The laser probably will do finer pitch work. There are some issues though, like light spreading and such. I'd go with one, but I don't want to have to deal with developer and etchant and I also want a CNC doing the drilling. And I want to be able to put part of a circuit done on a board, then add to it. You can't do that with etching. I can probably do that with isolation routering.

someguy
Sat, 07 Feb 2015 06:58:17 GMT

I bought the 3040 today. It has ball screws. I also ordered a smoothie board for it. Being that I no longer have a PC with a parallel port and I don't intend to run Mach3, I'll run it with the Smoothie board. I like the idea of being able to download code to the smoothie board instead of tying up a dedicated computer for it. There might be boards out there that are better than Smoothie, I haven't looked. I like Smoothie because its OS and runs GRBL.

jpcaram
Sat, 07 Feb 2015 16:53:10 GMT

I had never heard of the Smoothieboard. It looks like a big complicated piece of hardware. I simply use an Arduino UNO with GRBL and a stepper driver board.

someguy
Sat, 07 Feb 2015 18:02:20 GMT

I've built 4 CNC machines using a variety of control systems. Smoothieboard is the simplest, easiest and most powerful way to set up a stepper machine. Connect power supplies, connect stepper motors, tune it and use it. The great thing about GRBL and Smoothieboard is that the G Code and motor control loops run on a micro controller where they should. The PC that connects to the Smoothie board is used for generating, editing and downloading the G code, as it should. Windows was never designed to bash parallel port bits. The 4 and 5 axis Smoothieboard controllers have a network connection. All of them have a USB connection. Its easy to have a single PC/tablet/laptop set up with a good gcode sending package and use it to control all the machines in the shop. And it works great.

flatbear
Sat, 12 Nov 2016 11:57:07 GMT

Another + for laser is to add UV sensitive solder mask, and possibly even silk screen in another layer. I've only tested solder mask so far, seems to work when using low enough laser power. I aslo have a 3040 cnc but would like to avoid the fiberglass dust getting to my bearings and screw so I'm looking into the laser