> > Pretty nice subject to dig into. In the last few days I returned to the > Cam Design and Manufacturing handbook of Rober L. Norton to try and emulate > the lobes I'm doing mostly and get the equations right. I'm not gonna lie, > it's not an easy subject and I'm getting too much info too hard to digest > but oh boy how thrilling and exciting the subject is. And the good thing > is, all the math involved takes you right into the splines subject wich is > another exciting subject. Anyway, I'm taking it easy because I don't have > enough time to put all my attention into it but I'll try to repliate as > soon as possible the low lift roller followed cams that are the most common > nowadays. Until then, I will keep using look up tables since they work just > fine. >
Did I mention the word subject lately? Lol. I just noticed... El lun., 13 jul. 2020 a las 18:55, Leonardo Marsaglia (< ldmarsag...@gmail.com>) escribió: > In an ideal world, where Peter has infinite amounts >> of time and interest, the entire hal ecosystem could >> be put on the fpga. Practically, though, it is tricky to >> figure out exactly where the line should be drawn >> between servo thread modules running in the main >> processor and "base thread" components that run in >> the fpga. The fpga is parallel logic, so is well suited >> to encoder counters, pwm generators, and step >> generators. Motion planning would be a nightmare. >> Offset generation is in-between, as you need to >> connect different (arbitrary) axes, with different >> scaling factors. Similar to electronic gearing, but >> with offset as a real-time input. The fpga component >> would need to combine the "input" axis feedback, >> the "output" axis value, and a source for the cam >> profile (lookup table). Size of the lookup table would >> be an issue, as well as loading it. Specifying the >> profile as an equation would reduce the memory >> requirements, but would be arbitrarily complex. >> Perhaps a 3rd order polynomial would suffice. I'm >> sure Peter would love to implement that as well. > > > Pretty nice subject to dig into. In the last few days I returned to the > Cam Design and Manufacturing handbook of Rober L. Norton to try and emulate > the lobes I'm doing mostly and get the equations right. I'm not gonna lie, > it's not an easy subject and I'm getting too much info too hard to digest > but oh boy how thrilling and exciting the subject is. And the good thing > is, all the math involved takes you right into the splines subject wich is > another exciting subject. Anyway, I'm taking it easy because I don't have > enough time to put all my attention into it but I'll try to repliate as > soon as possible the low lift roller followed cams that are the most common > nowadays. Until then, I will keep using look up tables since they work just > fine. > > > El lun., 13 jul. 2020 a las 18:18, Sam Sokolik (<samco...@gmail.com>) > escribió: > >> My initial component was based on this formula.. (after racking my brain >> on how to do the math - I googled) >> >> >> https://math.stackexchange.com/questions/41940/is-there-an-equation-to-describe-regular-polygons/41954#41954 >> >> >> It has slightly more smarts to do slaved radius and such - oh - and I >> hacked in a D shape too.. It would be cool if it could take in a dxf >> file >> of a shape - or cheap and dirty have a gcode shape that the component >> could >> 'scan' in. >> >> On Mon, Jul 13, 2020 at 1:49 PM Gene Heskett <ghesk...@shentel.net> >> wrote: >> >> > On Monday 13 July 2020 13:56:47 Chris Albertson wrote: >> > >> > > Actually making a hex head on the lathe would best be done using a >> > > microcontroller. FPGAs can compute trig functions but I think the >> > > method used is to first implement a "soft CPU" and then run code >> > > written in C that uses math.h That is a silly-expensive why to >> > > replace a $5 STM32 chip. >> > > >> > > But really, the Lathe spindle does not run so fast and you can write >> > > this code as a HAL component that runs in the Servo loop. I wanted >> > > out how I would do this last night and was stumped on the math until I >> > > remembered the law of cosines and "SAS" triangle problems from some >> > > class I took in the 10th grade. Look those up on Wikipedia and then >> > > it is not hard to computer the cross slide position as a function of >> > > spindle angle. >> > > >> > > The hard part is getting such a good cross slide setup with no play of >> > > backlash >> > >> > Does 2 thou count? But I'd be more concerned with following error. A cam >> > for valve motion is not a sine wave by quite a long row of apple trees. >> > >> > > On Mon, Jul 13, 2020 at 9:35 AM Gene Heskett <ghesk...@shentel.net> >> > wrote: >> > > > On Monday 13 July 2020 12:00:19 Peter C. Wallace wrote: >> > > > >> > > > >> > > > ROTFLMAO, Peter see's right thru us. ;-) But seriously, the FPGA >> > > > does seem like the ideal place for such a module. On chip com with >> > > > the chosen stepgenerator removes that particular bandwidth limit. I >> > > > could also see it doubleing the size of the FPGA needed so its not >> > > > going to be free. I think, not knowing the first thing about >> > > > writing FPGA code. :-( >> > > > >> > > > [.. >> > >> > >> > 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) >> > If we desire respect for the law, we must first make the law >> respectable. >> > - Louis D. Brandeis >> > 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 >> > >> >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
