On Sunday 04 February 2018 21:20:11 Gene Heskett wrote: > On Sunday 04 February 2018 18:50:50 tom-...@bgp.nu wrote: > > That is a good question, and one we have recently asked ourselves. > > In fact we changed our threading routine to fix the RPM because at > > least then the spindle is not constantly accelerating and > > decelerating. But, to be honest, CSS should work fine, all it does > > it change the spindle speed for a given diameter. It does add a > > variable to the synchronization though (since it needs to > > accel/decel). > > True, and in either case, g76 or g33.1, I never start closer than > around 5 turns off the end of the workpiece. And once you see its not > carving up the fixtures you must resist the temptation to up the > spindle speed and get it done, for that, find some scrap in the > corner, if it works, then crank it up and do it right. > > (but on coarse threads, stay below 50% of the axis speed capability. > It must have that reserve to get properly synchronized) > > I just replaced a bob in my mills setup. Between the first bobs piss > poor opto speeds, and the inductance of a 1600 oz/in motor, my z speed > was maxed out and in danger of a stall at 27 ipm. Replacing the motor > with an 8 wire 940 wired in parallel, driven by an ac powered driver, > got me to around 65 ipm. Just recently I replaced that bob with a $22 > fleabay Sainsmart, no opto's in its outputs, and that same motor is > now lifting the G0704's head at 110 ipm. The diff is the lag of the > opto's that aren't there anymore. I still had to bypass the opto's in > the encoder inputs, but then a 1000 line encoder on the back of the > motor, which gives something over a 7000 for a scale, quit working > with the opto's at around 275 real rpms. Without the opto's it tracks > perfectly to 3000 rpms. > > > Temporarily at least, I am a happy camper. Till I decide to find out > how much faster I can move the xy's, (I might get them above 100 ipm > too!) but ATM I am trying to see if theres a chance of a snowball in > replacing the pi running the big lathe, with a rock64.
Having brought the subject up, I went out and played with the mills .ini file. When I sat down to do that, it was maxed at around 70" for xy. And around 90 for z. When I turned it and the lights off and got up, it had been moving at 140 ipm for the first 3 axis's for several minutes. Thats taking advantage of the much faster pulses coming out of the sainsmart bob. It does make a difference! And I'll goto bed with a satisfied grin on my face. :) > > > However, even with fixed RPM we still cut better threads if we start > > well off of the start of the thread giving the machine more time to > > synchronize. That is, when we start threading from 0.25 to -1 we > > get better threads then we start threading from 0 to -1. -Tom > > Thats to be expected, and in round figures for the thread sizes I've > cut, a good starting point. Bigger, coarser threads will need more > room of course. > > > > On Feb 4, 2018, at 2:08 PM, Gene Heskett <ghesk...@shentel.net> > > > wrote: > > > > > > On Sunday 04 February 2018 13:52:33 andy pugh wrote: > > >> On 30 January 2018 at 22:42, <tom-...@bgp.nu> wrote: > > >>> We read that G33 will wait for spindle-at-speed before looking > > >>> for the index pulse. But our spindle-at-speed signal seems to > > >>> be high during the full cycle once the spindle speeds up the > > >>> first time. > > >> > > >> How is your spindle-at-speed signal calculated? > > This is still a good question, Tom. If using a wcomp, how is it being > setup in your hal? -- 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emcfirstname.lastname@example.org https://lists.sourceforge.net/lists/listinfo/emc-users