CNC Milling CU clad board for PCB prototype fabrication

Fiberglass really wears tools down quickly, and I don't know if I'd want it washing through the coolant system of anything I own.

PC boards are specified in Gerber format, you'd have to translate this to a CNC file -- there may be programs, though.

There's quick-turn houses that'll put a board in the mail at 5:00PM if they get it on their website by 6:00AM -- and it'll be tin plated and really really plated through. Furthermore if you're in a major metro area you may be able to pick it up by courier. The only thing you wouldn't get would be the fancy teflon or other board materials.

pc houses are a better idea.

carbide tool> I am looking into purchasing a Sharp 9x42 3-axis CNC mill. I have since

I don't know about the plated through holes, but I watched a circuit board milling and drilling machine run once. The spindle speed was HIGH comapred to the mill you describe. 30,000 or 40,000 rpm I think. And it drilled and routed FAST! The machine was built on a base that basically consisted of a huge granite surface plate. All that being said, a 9 x 42 3 axis cnc mill is the better choice when it comes to making parts out of metal. If parts are only being prototyped in small quantities then the slowness of the mill won't be the big limiter in getting parts done fast. Your 3 axis mill can make lotsa metal chips and take pretty good cuts. The big circuit mills (or routers) are specialized, being only good for doing circuit boards really, and they must be more expensive. I've seen several of the machines sitting idle and the smallest still looked like it would cost much more than the mill you are looking at. Sharp mills start at about $16,000 US. They are a bridgeport copy. They look like they're from Taiwan or China. Maybe spain though. ERS

I suggest you get the mill and use it for cutting metal, and use PCB houses to make the PCBs. With RF, it can be handy to be able to create PCBs (about the only case where it might be justified, IMO).

The main maker of the prototyping machines, AFAUI, is LPKF:

Check google groups for stories on them-- while they work, I don't hear a lot of rave reviews. If you want to use the mill you'd need a high spindle speed, a tiny (usually conical) cutter and you'd get nasty abrasive fiberglass all over the machine too. You'd also need software to create toolpaths from Gerber files.

Best regards, Spehro Pefhany

There are various Internet suppliers that can ship you a proto board in less than a week for a minimal amount of cash. These will be multilayer, etc.

If they are doing RF circuits, they are going to need "good" PCBs to avoid signal issues. RF design is pretty involved. No offense, but cutting RF boards is asking for trouble.

Right on Spehro -

I was LPKF trained - good training - nice software (the new stuff) The old stuff was good and great for a hacker that needed to tweak everything every time.

Yes I have done double sided RF grade pcbs but mostly CMOS grade. Used 8 and 10 mil two blade mills.

The superior flatness that must be maintained across the entire pcb can be a nightmare. How thick is the metal and just how thick is the various layers beneath. Cut to deep and there goes Z. Remember traces cross others that are in different planes.

The side load pressures on an 8 mil end mill can be high when the cutter (carbide) dulls after a hundred or so inches. I have handfuls of broken carbide endmills.

I think a vacuum table would be nice, but then once you drill or mill through - there goes the air.

It just isn't as easy to do on a Big mill as one thinks.

Martin [ former job did that for fast prototype circuits ]