On Jan 25, 2009, at 6:47 PM, solarwind wrote: > has anyone tried making PCBs using a CNC machine? Sounds like > a really cool and fast way to make SIMPLE PCBs with almost no mess - > provided you have a CNC machine. Yes. A couple of years ago I blew some bonus money on a used LPKF. Many of my pithy observations on the disadvantages of no PTH or soldermask are based on my experiences with it. I've posted observations before; let's see if I can find them. Ahh: >> I bought a used LPKF from eBay a couple years ago for hobbyist >> usage. Less than half the price of the cheapest new unit... >> >> I don't know if it was worth it. I'm pretty sure I'm still far >> behind where I'd be $-wise if I'd sent every board I've made >> (including the N iterations of some of them) to a professional >> fabricator. It's nice to be able to go from eagle design to >> SS PCB in a couple hours, especially for the tiny boards that >> aren't quite right that I tend to make, but often the several >> hours of baby-sitting needed don't come along for quite a while, >> and I could've sent them out. >> >> It's a pain not having Plated through holes. Yeah, the newer >> systems have some PTH system of somesort, but it adds to the >> time and complexity of fabrication... >> >> It's a pain not having a soldermask. >> >> Tools and other expendable items are expensive; you can buy surplus >> partially used drills for cheap, but the mechanical etching bits are >> uncommon, without many providers, and rather expensive (and they >> wear out pretty quick.) (update: there are some third party etching bits that are cheaper that I need to try out. Soon. Maybe.) >> >> I have my doubts about it working very well below about 1mm pin >> pitch. While the specs say you can get 0.2mm isolation (with the >> standard tool), you're looking at a V-shaped trench, so if you >> were hoping to do .5mm TQFP with 0.3mm lands 0.2mm apart, you're >> at the very edge of possible, and you get a pattern in the third >> dimension that is exactly wrong for helping to position the packages. >> (trenches for the leads to fall in, between the pads.) Did I mention >> that it's a pain not having soldermask? >> >> Steps for more than 2 layers would add additional complexity and >> cost. Did I mention that it's a pain not having PTH ? >> >> It's really noisy. I think they rig the trade-show demos where it >> seems >> to run at only "moderate" noise levels. Or maybe the vacuums have >> gotten better since the one I have. >> >> On the bright side, it's a pretty good CNC drill even if everything >> else stops working. You can easily have complex board outlines and >> internal cutouts and such that are rare to find in "prototype" PCB >> houses. You can do signs and (2D) CNC-router type projects other >> than PCBs. The software works ok, isn't hard to use, and seems to >> offer capabilities far beyond "free" stuff (like EAGLE's >> OUTLINES.ULP) I've seen homebrew CNC machines aimed at the same sort of purpose, and the differences between them and the LPKF are dramatic enough that I wonder whether the homebrew machines really work at all. The LPKF has this big thick aluminum plate for rigidity and flatness of the PCB material, and whopping big stepper motors to drag the cutter sideways through copper and fiberglass... BillW -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist