Any movement involving the rotary axis is limited to the old trajectory planner - 1 segment look ahead..
sam On Tue, Jul 4, 2023 at 1:47 PM gene heskett <ghesk...@shentel.net> wrote: > On 7/4/23 13:31, Marius wrote: > > Hi > > > > I have been trying to get a rotary fourth axis setup going with the help > > of regular and knowledgable contributors to LinuxCnc. We came up against > > a brick wall as many other project developers have done. > > > > The problem seems to be that our trajectory planner lack the ability to > > look ahead for any rotary axis. This means that a coordinated move that > > includes a rotary move will be dysfunctional at best. > > > Not true Marius, if you are having problems, something about your config > is wrong. I am presently carving a 2 start screw in wood with my B axis > on the 6040 gantry mill. And its accurate to a fraction of a degree > anyplace in the 400mm length of that screw. With no PID's in use on > that machine. All you should have to do is calculate the end points > related to where it starts for the b axis and issue the two end points > in the same command line. I carve a two start buttress thread by pre > positioning at the shape point of the tooth, and carve that position for > the length of that screw. That rotates the b axis in perfect sync with > the y motion. At the far end of the screw, I add 180 degrees to the b, > move it that addition 180, then come back to the y starting point with b > coming bavk to 180, which is about 6mm off the end of the screw, then I > move b back to zero, reposition the tool for the next pass, and do it > again till its done. The 7 degree angle of the load bearing face of > that thread is established by a wedge under the motor, an angle > duplicated in the tooths shape. The nuts are printed on a 3d printer in > PETG, with a dozen teeth engaged in the length of the nut. > > There are no PID's and my B axis is a 3NM, 3 phase stepper/servo driving > a 5/1 worm which is driving a square socket that turns a 2x2 stick > nearly 600 mm long.live center at the other end of the stick, shimmed to > reduce the z motion required to do as close to a true cylinder the > length of that thread. And it all Just Works. My Z axis is also driven > by a 1NM version of that stepper/servo. > > Start by checking your .ini file. under: > [DISPLAY] > you should have something like this: > GEOMETRY = XYZA > then down file a ways: > [TRAJ] > AXES = 4 > COORDINATES = XYZA > > Now, that's wrong but my i/o channels are limited to 4 axis so my B axis > is actually wired to what would be the A terminals in the interface as I > am using a 5i25 and a 7i76 plus a std breakout for other functions. A > 7i90HD would fix that but bring another wagon load of shekels for > 7i42TA's, takes 3 of them as the 7i90 has no buffers to protect the fpga > used from 5 volt stuff. I've forgotten how, but on screen in axis it > does show as B. > Check the above, the rest of my .ini has it as A and JOINT_3. > > Digging thru my .hal file will get more complex as its been a couple > years since I first rigged a different B axis. > > So start with the above. > And have a happy 4th Marous. > > > I understand that there is a free trajectory planner on offer to > > LinuxCnc but it has not been integrated. It would seem that some lack of > > skills or time has a role to play in getting it integrated. > > > > I unfortunately do not have the skills nor the time to tender to assist > > with this however, someone made the suggestion that maybe the community > > could embark on a fund raising project to enable us to pay for someone > > to get the trajectory planner integrated. I am sure that many would > > stand to benefit from this and other users that I have spoken to has > > indicated that they would gladly contribute. > > > > I would at least want to start a discussion around the idea. > > > > > > Regards > > > > Marius > > > > > > > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > . > > 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, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/> > > > > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
