On Friday 09 October 2009, Hubert Bahr wrote: >Just some thinking out loud!! Is it possible to put a rotation detector >on a spindle, use it as an input to EMC and then have EMC drive some >type of digital to analog converter to change the speed until it agrees >with the desired setting? Based on some past discussions on the list, >I believe the answer to be yes. If so, what type of rotation detection >is needed? What is the best way to convert the EMC output to be a >control force for the spindle? > I am talking about a spindle on the X3 Seig Mill. I am planning to >convert the current gear drive to a two range belt drive, and since the >current controller appears to use a pot to adjust the speed and a switch >to change direction I believe I could use some type of control voltage >and a relay to replace the pot and switch. I would appreciate any >suggestions as I explore deeper. > >Hubert
Hubert, I suspect, but don't know for sure, but PMDX makes a card called the PMDX-106, which with some booster relays, took the VSD card out of my micromill, put it in a box with the PMDX-106 and put it under emc control quite nicely. Now, the rest of the problem is probably a hal verse or 2 once the actual speed of the spindle is known to emc. There are folks here who can probably help with that part. As a side comment, the VSD from my micromill has very high gain, and without any feedback, I can hog the cut and blow the fuse without ever detecting a sag in the speed I hear. That got a bit tiresome and expensive for fuses, so my spindle motor now has a 150% jury rigged ammeter to show me how hard the motor is working. That makes me the relay element between keeping the motor working fairly hard, and the feed override slider to adjust it. It seems to me that could be linked, taking me out of the picture long enough to go make a fresh cup of tea. Based on that, you may want to see about using the feedback error to also modify the feed override & slow the cut down to where the motor can handle it. Using a many turn toroid inductor, running one of the motor wires through it, rectify the output and a wee bit of smoothing filter, one could automate the feed override to always run as fast as the motor has the power to cut. This should approach the ideal cutter life too. Yeah, I dream a lot too, but this seems do-able to me. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> "In matters of principle, stand like a rock; in matters of taste, swim with the current." -- Thomas Jefferson ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
