John, Do you know if the same algorithm is used for G76?
Thanks John On 6/8/2012 12:56 PM, John Kasunich wrote: > On Fri, Jun 8, 2012, at 09:20 AM, gene heskett wrote: > I first observed this problem on my lathe a few months > after G33 was added. I could hear strange noises as the > motor first accelerated to higher than the proper speed, > then decelerated again. I also got bad threads on the > end of my part, because the sync process was using a lot > more Z distance than it should. I described the problem > to Chris Radek (who implemented G33) and he worked out > the following fix, which is in there now: > > At the beginning of each G33 pass, LinuxCNC uses the spindle > speed and the machine limits to calculate how long it will > take Z to accelerate, and determines how many degrees the > spindle will rotate during that time. It then adds that > angle to the index position and computes the Z position > using the corrected spindle angle. That means that Z will > reach the correct position just as it finishes accelerating > to the proper speed, and can immediately begin cutting a > good thread. Z will never have to move faster than you > would expect given the spindle speed and thread pitch. > > The downside of this fix is that the offset is different > if the spindle speed is different. I was worried about > that at the time, and argued with Chris about it. But > I couldn't come up with a better way to solve the problem. > It has been at three or four years now (maybe longer?), > and this is the first time someone has been bitten by > this particular behavior, so I think Chris was right. > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
