Hi Lowslow
You can simplify the support bearing even further by using one of the double row angular support bearings from SKF amongst others. These consist of two AC bearings in a single housing with an internal pre load. These only require a simple threaded retainer for the screw and a housing that retains the outer of the bearing properly. The cost is also very reaqsonable as they appear to be on the prefered bearing list for several manufacturers. Example 3201 2 RS is a 12x32x15.9 mm. I have been using some unmarked ones for some time and there is absolutely no detectable end float in the screws which is good for bearings costing less than $10.
Also you may care to note that NSK specify normal radial deep grove bearings for their ballscrews. For the very small screws they specify flanged radial ball bearings (see the data sheet for the RMA 0801 5C7S screws. Two flanged bearings being trapped by the securing nut on the lead screw which clamps the bearings into a simple bore. A very neat solution and one I ran into when searching for a ballscrew for the compound slide on a 7x12 lathe where there is little room if the screw is to be in the same possition as the manual screw.
Hope this helps some time!
Regards
Pat  |