Machine has a gap on the back side after third setup attempt

8

Hey Kevin,

  1. If your machine after homing shows a gap between the linear bearing (the big chrome-plated cylinder that sticks out the Y carriage) and the black front foot block on one Y side, but not on the other, l would first check if the distance with which the linear bearing sticks out of the Y carriage towards front is the same on both sides (same on left Y carriage as on right Y carriage).
    f704eb_79f93b74ee464b4b8e00184c30a45845~mv2
    Image 1: One of two linear bearings used in a Y carriage.

They are held with grub screws and it is not impossible that they are not equal.

→ If you finally measure the “gap”, don’t measure this gap, i.e. measure not from linear bearing to black front foot block, but from (black) Y carriage block to black front foot block. (by the way, one of the purposes of Bill @Machinist’s homing stops is that on stall homing, it bumps against carriage block and not against linear bearing)

  1. Did you already check your machine for rectangularity, like → described here? If you didn’t yet, please do it now. If then still there is a different distance between (black) Y carriage block and (black) front foot block on one Y side than on the other, you can do this:

    After you ensured that both diagonals are perfectly equal, then you can do the following:

    1. Shut down the CNC controller.
    2. Disconnect both Y stepper motors from the controller.
    3. Loosen slightly the four bolts on the top of every Y carriage that attach the X rail to them.
    4. Move both Y carriages towards front until they both touch the front end.
    5. Retighten the eight bolts.
    6. Restart the controller.
3 Likes