On Sunday 17 January 2016 17:43:51 John Kasunich wrote: > On Sun, Jan 17, 2016, at 04:58 PM, Gene Heskett wrote: > > Greetings all; > > > > I don't mind saying that this is getting old, as in Jurassic. > > > > pcb outputs terrible drill/mill code, so I converted every hole it > > needs to drill to a simple hole with a .03125" mill. Works great, > > but there are 4 to 7 holes that need to grow a bit, and 6 thou will > > probably cover the bigger ones I need, when added to the diameter of > > the drilled hole. > > I would think that even a good tight mill isn't going to do a great > job circle-milling a under-0.040" hole. > > If I was making the PCB I'd let the milling machine drill all the > holes the same size, so they are located accurately. Then stick a > number drill in either a drill press or even a dremel and enlarge the > ones that need to be bigger. 4 to 7 holes would be done in a couple > of minutes.
7 holes per board, thats 28 when making them 4 up. I've tried that, but the drills tend to grab and pull copper loose and other such damaging foofurah. I wish I had some single sided board. What I am doing is drilling all the way thru the board from the bottom face up on the table, just far enough to clear the copper on the bottom (the component face) of the board, without doing any real damage to the micarta sheet under it. I can see the marks, but I can't feel them. When the pcb is removed from the table and turned over, I took a sharp drill of about 89 thou, and using the hole for a guide, cleared the copper away for about 20 thou around the hole so the component leads wouldn't touch it. But its a steel drill, and mucking around in that glass, its in serious need of another trip to the Drill Doctor. As for accuracy, with an ebay ball screw kit in this Grizzly G0704 & some decent motors, its unreal, the mill goes down, the call is made to bore it another 3 to 6 thou in radius and even at 3 thou, I can see the bit doing a circle. Backlash of 1 to 2 thou has been carefully compensated, and under a 100 power glass, every hole, regardless of size, looks perfectly round. You can work with even smaller bits, but finding a chuck that can hold a #80 drill, without running 2x the drills size in runout is something I've yet to find. :( Which reminds me, trolling on ebay last night, I came across a 95 watt, 60,000 rpm 3 phase spindle with an R11 setup, new, for a hundred dollar bill. So I went looking for an inverter. 17 pages of inverters later, there was not a single phase powered inverter in any size below 2.2KW. Paying attention to all the cheapies rated under 400 watts, most stopped at 400hz and were used, stripped out of "working" machines, but no one would guarantee them any farther than the shipping room door. None at any price claimed to go up to a kilohertz, which would be whats required for a 60,000 rpm song. Is there a specific brand and model that might drive that motor to top speed? Maybe a Mesanet board? Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
