On Tuesday 16 April 2019 14:34:15 Gene Heskett wrote: > Greetings all; > > While adding a couple timedelays and a couple or2's to my hal file, > basically to prove that I can pulse the spindle for the nominally 200 > msecs used to spin the nut on/off to release the collet and supposedly > drop the tool, or just drop it all, I came up against a designed in > problem. This vfd has a pid in it that will no doubt wind up if the > speed command is present for any great amount of time, so its possible > I might have to cobble up a set of PID params to essentially disable > that. Because I think I am going to need to have the speed present at > the VI1 input before I enable the fwd or reverse commands for the > timed 200 millisecs to drop or pick up the tool during the change. The > wind up in that case might be advantageous in that it might jerk the > nut loose, or tighten it tighter before the carousel puts the real > tighten on it. But likely difficult to control too. > > But I find its not possible to send this speed request before the > run/dir signals. I can mux2 the spindle speed inputs to the 7i76, and > have the as yet unwritten tool changer code issue the speed and > timings. > > Is that the choice? > > A secondary problem if I do the 3d printed tool holders inside the > collet sockets, like the orange pieces in one of the videos on > hack-a-day, depending on the tool to drop free when the nut backs out > the collet, is that the tool does not always come free, and this looks > like a showstopper problem that puts me back to buying a handfull of > nuts and collets so I can drop it all and then reposition the carousel > to pick up the next tool/nut/collet as an assembly. Either way, it > seems like I'll unavoidably need an automatic TLO setting to complete > the change.
Some more along the lines of finding out how much force I can figure on as being available to tighten or loosen the collet nut. I can get, for under a tenner, 4 ea 50Kg load cells and a processor board that converts the very low level diffs of a wheatstone bridge made out the these, things, and which give a serial output to 12 or more bits. So all I have to do is place the cell kit between a frame and the carriage and give it a squeeze to get a measurement. These are the same as used in digital bathroom scales. Has someone made up a serial protocol for a Mesa board that could collect this data, and show me in pounds or kg, how much force I can get out of this machine before a motor slips s "cog", which in turn determines how big around the carousel has to be to adequately tighten, and of course loosen it too. The module needs a clock, one output on a 7i76D, and one data input, so all we need to do is toggle the output line with the servo-thread, and read the bit with an input line. A bit bang receiver IOW. Do we already have such a blob of code? Thanks for any comments on my hair brained ideas. > I figure on a bigger > carousel than shown in the videos. That thought is driven by the > difficulties I've had with the hand tightened (with a pair of 12 to > 16" wrenches) on the ER32's on the G0704. > > I've wrecked parts and broken tools because they'll walk out of the > collet, dig too deep and finally break off. That bit of history has > cost me several hundred in tools so far. :( > Thanks for any wisdom shared. URL's etc. 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-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
