andy pugh wrote: > Called, unsuprisingly, "gantrykins" it lets you map more than one > joint to each axis, and as long as it is configured correctly the two > motors will home independently but simultaneously. A number of problems have been reported with gantrykins, is it now considered fixed? The problem is the two encoders need to stay in the same relative alignment throughout the approach to home sequence or it may bind the carriage. At startup, the gantry is relaxed, and the encoder counters will be cleared to zero. If the count on the two encoders will remain equal during the initial home move, then that should be fine. Presumably, they will be within a very small number of counts out of sync, and the final homing to each encoder's index mark will not twist the gantry any, assuming they both do the home-to-index at the same time. > It has a number of > issues which make it generally more trouble than it is worth (mainly > to do with world-mode jogging, because as a non-trivial kinematics it > makes a distinction between world-mode and joint-mode) > Yes, this is not a computer-savvy customer, so I don't want to drive them crazy with joint-mode. It really needs to stay in world-mode all the time. Obviously, if you jog one side of the gantry in joint-mode, it will damage the machine. > The problems with gantrykins are, as far as I know, all addressed in > an alternative one-axis -> many-joints kinematics called > "gentrivkins". Unfortunately gentrivkins only works in the > joints_axes3 branch of LinuxCNC (which is currently quite up-to-date, > as far as I know, but isn't available as a package That may be a better solution. I can handle getting him a custom install from source, if needed. But, I had hoped to be able to do this without building a gantry machine here just to understand the homing issues.
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