On Tuesday 31 March 2020 00:11:56 Sam Sokolik wrote: > The encoder on the motor that goes back to the stmbl is pretty high > count - like 20k/rev. But only a small ribbed belt between the motor > and the spindle. (why I put the gear tooth encoder there) > The ribbed belt, aka a polygroove can handle lots more power than a v-belt of equ width. But it is not without a very small slip angle so is impractical to turn an encoder if you intend to do any rigid tapping. Putting the A/B on the rear of the motor was about 4 hours work because makeing the motors back shaft was a bit of a problem. I used the socket in the back of its flush shaft as a center drill starter, and drilled about 10mm deep, then tapped it for a 3mmx.7 cap screw. Then I made a hollow brass extension shaft about 15mm long with a flange on one end turned about a thou hollow on its bottom face so the outside edge sat on the 14mm motor shaft. 3mm cap screw thru it into the motor shaft.
The encoder came with a coupler that fit a .250 shaft. Then I made 4 standoffs after cutting away the top of the motor houseing leaving about 5/16 around the edge, drilled the 4 corners and made an alu plate to hold the encoder, and stood it all up on top of the motor with 4 shop made standoffs. It will take around twice the width in a toothed belt to handle the power. I've stripped the teeth off a cogged belt half a dozen times which in turn burns up the plastic pulley on my 7x12, which now has a 1HP treadmill motor turning it and fed to at least 1.5HP by my choice of psu's. Back to the G0704, I already had a home-made optical encoder on top of the spindle so the index pulse remained connected to it, hence the need for some tally switches on the knob, and some hal stuff to keep the pyvcp tach dead on. But the disk came loose a month back and totalled the opto's so the index is now a ferrous pin JBWelded to the side of the drawbar cap, and an ATS667. > Maybe a toothed belt is in the future.. - could gear it down a bit > more for slow rpm projects like this. I'd luv to be able to switch low gear from 1500 max down to 500, but... Unforch for me the drive in a G0704 is all gears, and made from cast nylon. Why I haven't munched them I haven't a clue because I'm hitting that 1HP 90 volt, 9.7 FLA motor with 125 volts at 17+ amps limit set in the Pico pwm-servo driver. I've some hal stuff to sequence the reversal, but despite that slowdown dictated by Z's inability to keep up, my turn-around times from 3k to 3k in the opposite direction run to about 400 milliseconds. Not too shabby for a piece of junk that isn't even square. The post leans about 2 degrees. Someday before the rapture I'd like to fix that. :( Stay safe Sam, you are a treasure of innovation. > On Mon, Mar 30, 2020 at 7:19 AM Gene Heskett <ghesk...@shentel.net> wrote: > > On Monday 30 March 2020 07:34:02 andy pugh wrote: > > > On Sat, 28 Mar 2020 at 19:40, Sam Sokolik <samco...@gmail.com> wrote: > > > > You can really see the spindle res... > > > > http://electronicsam.com/images/greenmachine/IMG_20200328_140150 > > > >.jpg > > > > > > Is there a motor encoder? You could try using that instead, > > > especially if it's a toothed belt drive. > > > > I highly recommend it. I have a 1000ppr on the back of my spindle > > motor, and some tally switches on the edge of the gear shift knob. > > So my operative spindle scale is something over 7k in high gear and > > a bit over 14k in low gear. That is such a fine resolution I can run > > the PID's Pgain well above 20. There is not a detectable slowdown or > > even working hard sound when the load comes on until I hear the iron > > in the motor squeaking when the Pico pwm-servo's current limit kicks > > in at around 17 amps. > > > > Cheers, 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) > > If we desire respect for the law, we must first make the law > > respectable. - Louis D. Brandeis > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
