How to adjust the fit clearance between the lead screw and nut of the workbench

There is always a gap between the longitudinal feed screw and the nut of the milling machine workbench, which is also the requirement of the movement of the screw in the nut. However, the size of this gap has a great influence on the milling process. After long-term friction and wear in milling, the gap will gradually increase. When the fit clearance is too large, the stability of the milling table will decrease, especially in forward milling, which has a particularly significant impact on the milling process. In this case, it is necessary to adjust the fit clearance between the lead screw and nut of the workbench.

When adjusting, first open the small cover plate at the turntable of the milling machine, loosen the small screws (3 in total, no need to disassemble), and then loosen the pressure plate. Then turn the worm clockwise to drive the adjusting nut (worm wheel) to rotate, so that the right end face of the adjusting nut is closely attached to the left end face of the fixed nut, and the adjusting nut is forced to push the lead screw to move to the left until the left side of the lead screw thread is closely attached to the right side of the fixed nut, and the fit gap is eliminated.

After the adjustment is completed, turn the handwheel to move the workbench, and there can be no jamming in the whole stroke of the workbench. If it is stuck, carefully rotate the adjusting nut and appropriately increase the fit clearance between the lead screw and the nut. The axial clearance between the lead screw and nut of the workbench should be no more than 0.20mm, and the axial clearance within the working stroke range of the lead screw should be no more than 0.05mm when forward milling is adopted. When the wear of the workbench lead screw is inconsistent in the whole working stroke length, the fit clearance cannot be adjusted by the forward milling method.

The gap between the lead screw and nut of the workbench should not be adjusted too small or too tight, otherwise the friction force will increase and the friction resistance moment will rise during the matching process, which will make it difficult for the lead screw and nut to move and accelerate the wear, which will directly affect the service life of the transmission parts.