If this is for a touch probe or something of the sort, you only need contact when the RPM < 500?
So, have a setup that if RPM is higher than 500, then a little solenoid that tensions the braid (not spring, as you say) is released so there is no tension on it. You want a copper braid around the spindle.. On Sun, 17 Feb 2019 at 09:01, Gene Heskett <[email protected]> wrote: > On Saturday 16 February 2019 22:46:26 Roland Jollivet wrote: > > > > > Any other ideas out there? Hopefully something that doesn't > > > > involve changing tools to use. > > > > I don't know what your spindle looks like, but to make an electrical > > connection to it, you could use a piece of earth shield. The woven, > > braid type that you find on better quality cables. These are usually > > plated copper, or plain copper. Soft and resilient. > > > > Find a place anywhere on the spindle to wrap it a 1/2 turn, pinch the > > two ends together, and pulled taut with a very light spring. I think > > it's easier, and better than trying to use brushes. > > Make a handful while you're at it to replace every 2 years. > > I've done that on the G0704 as its spindle has a reasonable speed, 3k > tops, and I can dial up 50 rpm in either direction. > > This is a 24k rpm spindle, with an er11 chuck. So its exposed surface is > around 9/16" in diameter. At full song, I expect it to burn up the > spring where the coils touch the spinning chuck. Something along the > lines of a dremel tool's brush would live much longer. And as it would > have to run on the narrow area above the wrench flats, plus the tir is > at least half a thou, it more than likely would need some sort of a > retractor simply because the brush is not able to track the tir and > maintain good contact at the higher speeds. Haveing rebrushed a dremel > or 5 over the last 65 years, you are wasting your time if you do not > also turn the commutator to reduce its tir. All you get is excessive > arcing because the brush is bouncing away from the worn commutator. > > That retraction is not a problem other than arranging to do it as the > spindle revs increase. Where I've used a tool as the contact, I > generally spin the tool backwards so as not to put cut marks on the work > when doing the measurements. Retracting the brush when the revs go above > 5k or so is something I haven't given any thought to. Its also possible > that some sort of a weak metallic brush could be laid against the > spindle, but what happens to it when your are spinning it backwards at > what would be creep speeds. Given the full song rpms, I don't see a > long life for any direct contact solution other than the carbon brush. > > As soon as I get the new interface I am building up and running so that I > have enough i/o, I'll put in home switches just so I can set sw limits > just short of crashes, then I'll probably write me a corner of the > workpiece finder using the new probe I installed today, making heavy use > of g38.2, (not applicable to wood projects though, darnit). Then > determine those x-y offsets and incorporate them into my code. The > natural progression then is to write a skeleton that incorporates all > that, making the next project after this one even easier. > > Basicly, I'm lazy, write it once, run it as many times as I need. ;-) > > Cheers Roland, 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> > > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
