Greenwatts

LM339 Shaft Bearing

Next step is to make a bearing surface on the spur gear shaft that will hold the shaft where it penetrates the top of the drive housing. Measure about 6mm above the top surface of the top of the housing by placing a flat piece of ABS across the top of the housing sides and next to the shaft measure up 6mm then lock two nuts together with the bottom of the two at the 6mm mark this will serve as a guide for filing the shaft. Use the edge of a large flat file and file down a 6mm section just below the nuts to end up with the shaft as in the bottom right picture. You can make the diameter equal to a 1/4 drill which you will use later to make the split bearing.