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
