On Sunday 28 September 2008, Jon Elson wrote: >Gene Heskett wrote: >> On Sunday 28 September 2008, Jon Elson wrote: >>> But, no reversing, I assume. >> >> Ahh, emc does have as one of its m# commands, a "start reverse", and I do >> have it hooked up, not terribly useful without the encoder, but ISTR it >> does work, I have it tied to one of those teeny relay's in the PMDX-106 >> which in turn is clanking a 10 amp P&B DPDT relay to swap the motor leads. >> So reverse works both from that teeny little toggle on the PMDX-106, or >> if its centered, from emc. > >Yes, of course, you don't need a servo amp to make the motor reversible, >just not clear how well the Chinese motor speed control would handle >plug reversing. Since my servo amps handle current limit gracefully, it >works pretty well.
Mine do not, if I flip the reverse switch without waiting for the suicide brakes to stop the spindle, it will summarily blow the fuse. When the spindle is off, there is a 8 ohm 20 watt r across it on the back side of the enable relay contacts. Brings it to a dead stop from 2500 revs in about a second flat. > >>> I'm a lot more interested in 4-40 and 6-32 size threads than 1/4". >> >> I might go up to 10-32 or 10-24 for interest, but 4-40/4-48 is about how >> much power that spindle has. I suspect without the encoder to pace the >> feed with, all I'd do is make more practice sessions of removing broken >> taps by ED means. Been there, done that, its a PIMA. :) > >Well, I did some test holes in 1/8" aluminum with 10-32, and it worked >fine. I could hear the motor slow down a little (right now the system >uses a servo amp but it is actually open-loop as for speed control). I >did put the gears in the low range speed, I'm pretty sure it would have >stalled on the high range. Hard alu yes, the stuff I have in a 7" square bar of about 2 feet long, nope, too gummy. But that is what I carved those bearing blocks for the z axis out of, so its good for something. >>>> How did you attach the encoder to the micromill spindle? Patented? :) >>> >>> No patents for me! Starve the lawyers! A man after my own heart. Like Bill said "first we kill all the lawyers" >>> See the last picture here http://pico-systems.com/minimill.html for a >>> good view of the encoder and mount/drive. I found some nice plastic >>> pulleys in my junk drawer, and an oddball encoder with index. >> >> Ahh, but that's a minimill, not a micromill. > >I've never gotten this minimill vs. micromill figured out, this is the >150 Lb machine. I think mine was maybe 100 even in the crate, its gained some since, bigger tables & what not. >But, I'd guess a number of machines have something on the upper spindle >that could be used to attach a small pulley, similar to what I've done. This one is all plastic gears internally. The only thing sticking out of the top of the gearbox is the drawbar bolt. The thought has crossed my mind to rig a pair of plastic gears to engage one of the two on the spindle, with that serving as timing belt pulley that would bring it out through the side of the box & hook it up to an encoder, but its just a thought at this stage & probably the machine will morph into an X3 before that happens. If I feel like doing all this over again, I'll be 74 in another week & I'm slowing down. Or just tired maybe, if you back out of the emc directory, there is a Garage-pix there too. I've built that 98% single handedly since the end of May. I have a bit of soffit yet to put on the back, and up and over the gable end, and a few pieces of siding to put up on the end & that's done. The only thing I contracted was the floor, $3600 in concrete. >>> I also need to figure out how to get an on-screen RPM display. I really >>> wanted to work on that at the CNC Workshop, but got distracted. >> >> The road to hell, Jon. ;-) And really that does seem to be a simple counter attached to the encoders output, and a bit of math. And of course the display real estate. :) Just zero the counter on the backside of the read strobe & read the accumulation in the slow display loop. >Well, you never know, when starting in on a project. But, I DON'T want >to bring the same-old, same-old machine to a show two years in a row. There are those that would consider that to be 'poor form' :) Since I'll never make the show unless you move it to WV, there isn't much danger of me being guilty of that. Since its 95% hobby (the last time I used it 2 weeks ago was machining a bunch of mortises in some cherry sticks that will be an entertainment center eventually) what I need the hobby to do determines if its big enough for the job. FWIW, it did a better job than I can do with a wood chisel and mallet, which is how I cut them for the gun cabinet I made a year ago. All I had to do was square up the corners and a table saw cut tenon fit well, or a little tight. And a lot less sideways miss-alignment that wears out a lot of sandpaper. :) And for sure faster! -- 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) Faith may be defined briefly as an illogical belief in the occurence of the improbable. - H. L. Mencken ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
