For making sure that the hammerhead T-nuts rotate when tightening I pre-apply a weak threadlock to the screws and it gives reliable feedback when first 90 deg of rotation is easier than the rest, indicating proper alignment.
just had an idea about the gantry problem. You could use a slightly longer x-gantry extrusion and mount on the other end of the extrusion a counter weight. then you can use your second motor wihtout any issues, and it could be even more stable then the original minion gantry, you just need to find the right weight for it
For making sure that the hammerhead T-nuts rotate when tightening I pre-apply a weak threadlock to the screws and it gives reliable feedback when first 90 deg of rotation is easier than the rest, indicating proper alignment.
just had an idea about the gantry problem. You could use a slightly longer x-gantry extrusion and mount on the other end of the extrusion a counter weight. then you can use your second motor wihtout any issues, and it could be even more stable then the original minion gantry, you just need to find the right weight for it