On 01/29/2016 02:03 AM, Gene Heskett wrote: > All of the stuff I might use to make a pcb can be obtained with stop > collars so the stickout is within a thou of 1.000".
If all you're using is 1/8" shank carbide PCB drills, I'd get a good high precision 1/8" collet. It can be higher precision because it's designed to grip a 1/8" shank, and not a 3-4 mm range. High precision means low runout. There is a strong correlation between cost and quality. You usually get what you pay for. You are very unlikely to find a high precision collet that's inexpensive, but you may find a cheap collet sold at a high price because the seller knows that some buyers assume it must be good because it's expensive. I've definitely noticed that there are items for sale that fall into two categories, genuine and counterfeit, with two corresponding price ranges. Some crafty sellers have learned that their profit is greatly maximized by selling their counterfeit merchandise (complete with a copied Samsung logo, for example) at the low end of the price range for the genuine item, fooling buyers into thinking they're getting a good deal on the genuine item, when they're actually getting a very bad deal on a counterfeit item. So if you want a good collet, I'd buy from a reputable source. There are definitely low quality knockoffs of precision collets on eBay, complete with the copied distinctive red/blue packaging. For some items on eBay and Amazon, it's almost impossible to buy the genuine article, because almost all of the items are fakes. If you want to grip arbitrary diameters of shanks on your full set of drill bits, you'll probably want the overlapping metric set of collets. A higher precision collet tends to have a narrower grip range, so an overlapping set of collets that will grip anything in that range may have .5 mm collet increments, at least on the smaller sizes. You may decide that you only need the high precision collet for those tiny carbide PCB drills, and a bargain set of metric collets will be good enough for an occasional HSS drill bit for a 10-32 tap hole. My import mill/drill spindle is guaranteed to have a lot of runout, so I should only buy high runout collets and line them up so the collet runout nullifies the spindle runout. That's my attempt at humor. It doesn't really work that way. But it is true that a high precision collet isn't going to fix a low precision spindle. BTW - I was very impressed with the two water cooled Chinese spindles I bought on eBay for my two CNC routers. The electrical and plumbing connections are the quality I was expecting, but the spindle bearings are phenomenal. Spinning them by hand, they just felt like quality. They advertise German bearings, and I assumed that meant there was a Chinese company called German Bearings, but wherever they came from, the bearings and related machining in these inexpensive spindle motors are clearly of high quality, and justify the investment in a good high precision collet. ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users