I have some spare encoders already. As I said, I want to use what is on the shelf already. To save a bit if cash seeing that I have to replace the spindle motor that burned out after one hour of working (testing light cuts). I had to replace it anyway with a VFD and new motor.
On 2014-07-15 16:39, Gene Heskett wrote: > On Tuesday 15 July 2014 09:44:32 Marius Liebenberg did opine > And Gene did reply: >> On 2014-07-15 14:00, andy pugh wrote: >>> On 15 July 2014 10:44, Marius Liebenberg <[email protected]> > wrote: >>>> What would the highest safe RPM be for a 2048 quadrature spindle >>>> encoder on the 7i76. >>>> I have to use some pulleys to mount the encoder on my spindle and I >>>> would like to use what I have on the shelf if possible. >>> 1:1 is the right ratio, if you want to use the index from the >>> encoder. The encoder on the 7i76 can do 10Mhz according to the >>> manual, so that should be OK to 292,000 rpm. >> OK so speed is not the problem. I will have to concoct another method >> to mount the encoder if it is better to have it 1:1 >> How do others do that on a lathe seeing that you cannot mount the >> encoder on the back of the shaft. The shaft is hollow for material to >> pass through. > I did put it there on mine, Marius, but made the encoder. > > The 7x12 doesn't have a lot of room for a disk so the diameter is limited > to about 2.75", but I made a 50 slot disk on my tightened up, ball screws > X,Y now, mill with the slot cuts as the outside circle, with one slot cut > another .099 longer on the inside of the circle for an index pulse. It > just clears the casting boss that the cover bolt screws into at the > top/rear of the cover. > > I made in eagle, a pcb to mount 3 of the honeywell HOA2001 series opto > interrupters that have active, schmidt triggered outputs, all in a row, > mounted across the top of the disk so that the center opto, setting > inline, actually sees only the long slot and the curvature of the slots > lets the outside two optos see only the slots. The disk itself is held > between the spindle bearing adjuster nut, and its locknut. I have made > several of them, with the latest and best being made from .015" thick alu > sheet that formerly lived in a dishwasher door to allow changing its color > to match the other appliances. Used a 1/32" end mill. The sacrificial > board under the sheet MUST be flat. > > Because its thinner than the nut threads, I put a dial on it and tapped it > with the back nut only snug to remove radial eccentricity as best I could, > then gave the locknut one last tap to tighten. > > I did have to file the back face of the adjuster nut to remove most of the > disks axial wobble, those nuts have pretty trashy faces. > > The disk obviously has a large central opening to clear the OD of the rear > of the spindle. > > The pcb did wind up having some tiny pots added so as to be able to adjust > the brightness of the opto's led's as a method to fine tune the A/B duty > cycles to 50%. > > I can round up the latest incarnation of the disk carving code, and either > carve the pcb or make the eagle files available if you'd like. Getting a > board house to do it and give you plated thru holes would be handier than > bottled beer though. > > The pcb is double-sided, and without the plated thru holes and that makes > soldering in the parts a bit difficult. With a bit more room it would be > better with 3 individual mounts though, much more leeway to adjust for > perfect quadrature timings that way. Gross adjustments in the timing could > be done by changing the number of slots of course, I started with 39, but > then found the next closest at 50 slots actually gave better timing. > > The Gcode for the disk can easily be massaged for a larger disk if you > have room after the change gears are removed as you won't need those > anymore. I started out with code that made about a 7" disk that I found > on the net and modified it to suit. Its maybe 125 lines of gcode. > > Cheers, Gene Heskett -- Regards /Groete Marius D. Liebenberg +27 82 698 3251 +27 12 743 6064 QQ 1767394877 ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
