Hello all,

I hope you can point me in the right direction. I am a complete newcomer to the forum and to CNC. I do electronics as a hobby and make PCBs fairly regularly and want to get a benchtop CNC unit to drill and route cut-outs in my boards. I have been looking at the Proxxon MF70 although the working area is a little small. I have seen the unit on sale with a larger working area so this would be perfect for me. My question is this:
What software would be needed to convert NC drill files from my PCB package to that used by the PC to drive the mill? On doing a little research i've discovered that for normal use people use a CAD program, then CAM and so on. Like I said, i'm a complete newcomer so any help would be most appreciated.

Thanks,

Nick

2 links on my website on the topic:http://www.pminmo.com/wiki/index.php?title=CNC_PCB_Milling

Eagle www.cadsoftusa.com has a user language program (ulp) for creating G-code for milling.

Kind of an overview of how a system goes together:
http://www.pminmo.com/wiki/index.php?title=CNC_System_Overview

Hope this helps.

DeskCNC imports both Gerber plots and Excellon drill files and converts them to std g-code. It will also generate g-code from .dxf and .stl files. As an added bonus it controls your machine motion with the help of a slave processor for step pulse timing functions!! Great product. The book "EasyCNC" was written specifically for beginning DeskCNC users.

www.deskcnc.com

For the record, I will be listing a converted MF 70 with motors, drivers, power supply, and DeskCNC license on Ebay in the next couple days. The complete package will be @ $1350.00 USD Buy it now. The software and driver box can be carried along to a larger mill down the road!

Ken
KDN Tool

CADSOFT looks like a very nice program.
Do you use a milling machine only to drill the holes in the PCB?
Thanks

I don't use a machine at this point to make pcb's. I do use Eagle extensively. The free version for the hobbiest is pretty remarkable, even the lowest license I have for $60 is unbelievable for the power of the tool suite. Schematic capture, pcb design and auto router for 2 layers for free to the hobbiest. In the beginning it is a little cumbersome, and I can't say the help file is that helpfull sometimes. Some tasks start better from the command line verses point and click from a menu. I've probably got 600 plus hours as a user, and continue to learn new capabilities that just blow me away.

Yeah I downloaded the demo and have started playing with it. I was just curious how the PCB gets etched. I was thinking you must print the scematic on a film then transfer it to the PCB and etch, Do you then use a mill to drill the holes?
thanks

PminMo,

How does a person pay you for a blank interface pcb? I Emailed you some time ago with no answer.

Also the links you posted about PCB manufacture keep giving me the notice that I'm unauthorized to view the pages. Is this a setting on my computer or... ?

Thanks

No, my webhost is changing servers, was supposed to be "seemless". Right now the only thing "less" is I'm less email services and my website has been on and off today. Needless to say I've contacted them citing my customer lack of satisfaction. The upside is faster servers and network once complete.

I think this is how it goes:
When you etch, your iron chloride or whatever eats away the copper on the board that you don't want (leaving the tracks unharmed). Well with a mill, you simply mill away the material you dont want. If you got the right sized drill bit, I see no reason you could not drill holes with the mill also.
The Proxxon looks like a good choice for pcb work with its high spindle speed.

Most PCB layout software exports in Gerber format. Included in that is a an Excellon Drill file that defines all of the drill sizes and locations. Several program import Excellon. SheetCAM (www.sheetcam.com) imports them and the tool changes (drill sizes and een sets up a matching tool table automatically.

If you use chemical processing then you drill, then use film on the resist coated board. You can also use the iron-on type toner trasnfer method for a positive resist method. The actual routing of boards is a little more complicated. You need to get from the Gerber of the traces to a DXF. DeskPCB does that easily and while it will give you g-code directly I just take the DXF and move it to SheetCAM and register the holes and route paths on the screen and do both operations from one package. I can hold 12 mil lines using the router methods (runs between pins) but you need a VERY flat surface and material or a floating head with depth control nosepiece. The best tool for doing fine work is a 60 deg carbide rotary cutter made for cutting fine lines. You have to be able to precisely control the depth of the width of your runs will vary from nothing to shorts.

I don't recommend the milling method for double sided (although it can be done with registration pins). On any double sided board there is the problem of no plated through holes and using wire layer jumpers or component pins solder on both sides.

For first protos I will layout the board and let it route and use jumpers for the top layer connections (if your PCB layout will do that). Then when the circuit is up and running I use the same schematic and let the auto router have both sides. It then goes to the prototype shop. You can get 5 boards with plated holes, soldermask and silkscreen for 15 to 20 each.