T-Series/Tensioning Timing Belt and Aligning Lower Axis Stages

Tensioning Timing Belt and Aligning Lower Axis Stages

The T-G-LSM series gantry systems ship with the lower axis fully assembled. It should not be necessary to adjust these stages. It is possible however, that the timing belt which couples the two parallel stages could stretch over time and need to be re-tensioned. It is also possible that one or both of the lower axis stages need to be removed from the baseplate. Whatever the reason, if the lower axis of the gantry system needs to be re-aligned, follow the procedures below.

Parts Identification

T-G-LSM Gantry System Components

Alignment Procedure

• Move lower and upper axes stages to a position where all the screws holding the stages to the baseplate are accessible.

• Remove top stage.

Upper axis stage removed

• Loosen cross-member screws.

Loosen cross-member screws

• Remove timing belt cover.

Timing belt cover removed

• Loosen screws holding stages to baseplate about 1/4 turn.

Loosen stage mounting screws

• Slide slave stage towards master stage to release tension on timing belt.
• Check that dowel pins are installed (2 for master stage, 1 for slave).

2 dowel pins should be installed as shown for the master stage

1 dowel pin should be installed as shown for the slave stage

• If dowel pins are not installed, install them. They should need only a light tap to insert. Use only 3/32" dowel pins.
• Push master stage against dowel pins and tighten screws holding stage to baseplate
• While holding slave stage against dowel pin, slide the stage away from the master stage until the timing belt is taught. Try to keep the stage as parallel to the master stage as possible. While holding the stage in position, tighten one of the screws near the motor end of the stage and one screw near the opposite end of the stage. Don't worry that the stages are not perfectly parallel. They will be aligned in the following steps.

Tension the timing belt and tighten the mounting screws on the slave stage

• Plug the gantry in and move the lower axis to about the halfway position of its travel.
• Slide the cross member around until the cable guide is aligned and tighten the cross-member-to-master stage screws. Leave the cross-member-to-slave stage screws loose.

Align the cable guide by moving the cross-member.

Tighten the cross-member-to-master stage screws.

• Re-install the top axis stage.
• Move the lower axis to the home position.

Re-install top axis stage and move lower axis to home position.

• Tighten the cross-member-to-slave stage screws.

• Loosen the screw you previously tightened near the maximum travel position of the slave stage. Both screws at this end of the stage should now be loose.

• Using the pot knob, move the lower axis towards the maximum travel position. The cross-member should move the slave stage into alignment with the master. When the cross-member gets close to the end of travel, stop the movement and tighten one of the screws at the bearing end of the slave stage to hold it in position.

• As the alignment of the slave stage changes, you will notice that the belt tension will change as well. The proper timing belt tension is very important for proper operation of the gantry system. If the belt is too tight, the lower axis will not be able to reach its maximum speed. If it is too loose, the backlash will increase. See the table below for the maximum speed of your gantry system when the timing belt is properly tensioned. The maximum speed is the best indication of proper tension. If the belt tension needs to be adjusted, loosen the cross-member screws and the mounting screws near the motor end of the slave stage and swing this end of the stage towards or away from the master stage as necessary to adjust the belt tension. Tighten one of the screws and repeat the alignment process described above. Properly tensioning the belt and aligning the slave stage is an iterative process and make take several tries to get right.

Speed Range for Properly Tensioned Timing Belt

Gantry System	Maximum Speed
T-G-LSM200A200A	10000-12000
T-G-LSM200A100A	10000-12000
T-G-LSM100A200A	10000-12000
T-G-LSM100A100A	10000-12000

• If necessary, you can remove the top axis and re-align the cross-member once the lower axis stages are parallel.

• Re-install the timing belt cover.