On Thursday 29 September 2016 08:49:50 John Kasunich wrote: > On Wed, Sep 28, 2016, at 09:35 PM, Robert Ellenberg wrote: > > That would certainly be convenient. What if we took it one step > > further and automatically limit the maximum spindle speed for each > > G33 segment? It would be ugly, but we may be able to stuff a spindle > > speed command into the queue before adding the line segment. > > Combined with a message to the user than this is occurring, it would > > be both safe and convenient for the user. > > That assumes that the machine has active control over the spindle > speed. Which is NOT necessary for threading and other G33 work. > > For example, my lathe has 16 spindle speeds which are determined by > how you set the belts on the pulleys. The S-word has absolutely no > effect on the speed. It doesn't matter whether you write M3S100 or > M3S10000, the spindle is going to start and run at the speed > determined by the belts. > > The spindle encoder tells LinuxCNC how fast the spindle is going and > thus allows for synchronized moves, but: > > 1) LinuxCNC can't change the speed if it doesn't like it > 2) LinuxCNC doesn't know the speed at the interp level, because the > S-word means nothing. Only the encoder feedback can tell it the > spindle speed.
I'll be in somewhat better shape with this Sheldon conversion John. Sure, mechanically I'll have the same old 8 speed spindle, backgear in/out plus 4 positions of the belt, but I'll also have a vfd running the 1 hp motor, replaceing its original 3/4 hp which had been fitted with a reverseing switch, which I'll likely have programmed for a 1/2 to 2 or 3x nameplate speed, so I'll have an ability to make use of such a feature. And depending on how fast the vfd can reverse it safely, G33.1 rigid tapping seems do-able. Much better if I can start a tap drill for say a 1/4" bolt, centered on the mating face of the chucks backplate and the flange of the spindle it seats on, drill so half the hole is in the backplate and half in the spindle flange and tap the hole & put a bolt in it to lock the chuck so it can't be unscrewed by a quick reverse. I had to do that to the motor in TLM as the flywheel/fan/pulley is screwed to the motor shaft. I put 2 such bolts in it, 180 degrees apart. 1st mptor I used a 10-24 set screw, wrecked/crushed it and the shaft so the 2nd motor has 2 solid bolts in it. Hasn't come loose yet. I've also put some ramping in the hal file to make the reversal a bit less violent. That limits the spindle speed for a g33.1 on TLM, but not from Z speed limits, but from turnaround overshoots, about 2.5 turns at 200 rpms in high gear, 4 or so turns in low gear because of the heavy motor flywheel. I've some hal stuff I can watch with a halmeter to tell me how many encoder counts this overshoot is so I can start the turnaround early enough I don't slip the tap or break it against the bottom of a blind hole. 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> ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
