Gantry: Gantry Replacement: CMC 8500

NEVER SKIP AHEAD ON ANY STEP!

Head appearance may vary from model shown, but the connections are the same.

Never pull/push on the drive shaft to move the gantry. Use the gantry arm to move/pick up the gantry.

Do not pick up the head using only the blade depth knob or the head cover. Pick up the head by holding the “D-Shaped” upper and lower head plates.

Follow these instructions if you have a Straight Line Trimmer installed, otherwise skip ahead to “Head Removal”.

Turn the shut off valve on the Blue Air Line, and unplug the Blue Air Line before removing the Straight Line Trimmer.

Turn the bottom locking knob Clockwise to loosen.

Turn the top locking knob Counter-Clockwise to loosen.

Slide the Straight Line Trimmer off of the Board and set aside in a safe place.

Click reset motors button on the cut preview and click OK on the release motors prompt.

Push blade cartridge release down to eject the blade cartridge. Turn off the air.

Remove the hood from the gantry by unscrewing the screws that holds it in place and set aside.

Move the gantry to the right side of the board until the foot block is off the board.

Disconnect the head power plug (square connection) from the head grabber arm.

Disconnect the air to the head by untwisting the two air fittings.

Remove the two 5/32” screws and set aside.

Roll the head down the gantry until it rolls off the gantry, taking care not to drop it.

NEVER SKIP AHEAD ON ANY STEP!

Remove the front right 3/16” stop screw from the alignment plate on the left bottom rail (located on the top of the bottom rail) and set aside.

Loosen the back left screw and T-Nut and slide the alignment plate to the end of the rail to remove. If your model only has a stop screw without the alignment plate, remove the stop screw.

Remove the 5/32” Allen screws and washers from the lower gantry plate.

Disconnect the air lines to the gantry by untwisting the air fittings.

Disconnect the board cable by turning the locking ring until it comes away from the gantry.

Look for Red Dots (only these screws are to be adjusted).

Loosen one full turn only the 3/16” Allen belt tensioner screw from the right bottom side of the lower rail marked with a red dot. Only loosen it enough so that there is some movement in the belt tensioner; about one full turn.

WARNING: Make sure you do not over loosen this screw. One full turn is usually sufficient.

Belt tensioner springs should be visible.

Locate the belt tensioner hole on the end of the belt tensioner.

Place the 5/32” Allen screw and washer we removed from the lower gantry plate into the belt tensioner hole. Tighten the Allen screw until belt tensioner is flush with the rail and the springs are not visible.

Go back and tighten the 3/16” Allen belt tensioner screw on the right bottom side of the lower rail marked with a red dot.

Lift the drive belt end out of the belt tensioner slot.

Pushing the drive belt end to the right may assist in getting a hold of it.

Wind up the drive belt, and rubberband it.

Repeat steps 1 through 9 with the upper rail.

Move the gantry to the left to dislodge the belt anchors. The belt anchors are sunk into the left ends of the rails and are attached to the drive belts. Lay the belt anchors over the drive belts and rubberband them together.

Hold the gantry on the bottom and along the gantry arm and gently roll the gantry off the rails on the left side of the board and set aside.

The gantry only weights about 30 lbs, but it is large and awkward, so having a second person standing in front of the CMC helping may be beneficial.

Before installation, look at the bottom set of gantry wheels. The bottom wheels are spring-loaded, the top wheels are on a center-pivot.

Move the top set of wheels as needed for ease of installation (picture shows gantry being put on rail from back).

Before installation, look at the top set of gantry wheels. Both sets of wheels are spring-loaded.

Wheels may need to be eased over the rails (picture shows gantry being put on rail from back).

Hold the gantry near the left side of the CMC and line up the upper then lower wheels of the gantry to the center channel of the rails.

NOTE: Installation is easier if you line up the upper wheels first, then slide the lower wheels onto the rail. Sometimes having a second person for this step helps.

Carefully ease the gantry onto the left side of the rails, taking care that all of the wheels line up. Upper and lower gantry ends must be slid on at the same time. Make sure that the drive belt lies within the channel on either side and is not pinched between the gantry and the rail.

Roll gantry past where the alignment plate was removed. Slide in the alignment plate from the end of the rail.

Replace the 3/16” stop screw into the alignment plate and into the left bottom rail. If you only have the stop screw, replace the stop screw.

Roll the gantry so it lines up to the alignment plate. Loosely tighten the back left stop screw, then the front right stop screw, repeating until the alignment plate is secured into position.

Roll the gantry to the far right of the board and back to the left to make sure it moves smoothly.