On Thursday, 28 April 2022 14:55:24 EDT andy pugh wrote: > On Thu, 28 Apr 2022 at 19:50, gene heskett <ghesk...@shentel.net> wrote: > > Ack the switches on the driver, its doing a /16 microstep. its a 1.2 > > degree per full step 3 phase motor. the motor is now driveing a 40/1 > > harmonic drive, and the harmonic drive has a 53 tooth output > > sprocket, > > which is timing belt driving a 60 tooth on the axle turning the chuck > > with the home switch on it. And that home switch is whats driving the > > 100 turn counter. > > I have no idea why you need a 100 turn counter. > To drive a couple comps to capture the number of steps issued to drive it exactly 100 full turns. That I should be able to divide by 100 to get the counts per turn, then divide that by 360 to get the number of steps per degree. But that gets me a very small number that doesn't appear to be related, cuz a command to move it 360 degrees=1 full turn is much less than a turn. This 3 phase motors encoder is not available to linuxcnc, only to the motors driver. And for this, real accuracy is needed, as it determines the mm per thread as well as a consistent stopping point. Its also a two start thread, as much so the plastic nut halves are identical while 2 start speeds up the vise movement as most vise screws are too slow for a wood worker and supply enough grip to damage the wood.
I do the 2nd start on the unwind backstroke by lifting the tool at the end, rotating it an additional 180 degrees, put the tool back down, then run both y back to its origin and b back to 180 degrees. Cutting the back side of a buttress thread is all that needs cut, but it must fit the tpmm of the nuts. I can calculate the b turns required from the total distance which varies with the y start as it effectively slides up and down the z slope, but nothing is correct if the b scale isn't, hence the emphasis on a dead accurate calibration by measureing the counts for 100 360 degree turns. Do you have a better way? > If this is about swapping tools mid-job on this wooden screw, then why > not just write two G-code programs, One to start with and one to > finish with? That part is already done. 2 subroutines. Its calibration of the b axis thats being a problem child. Thank you Andy. > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > 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, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
