Ball-bearing replacement for newer D2s with crank-lifts

Later Omega D2 enlargers with lifting cranks have larger diameter flanged bushings, also made of plastic. We've been unable to find exact ball-bearing replacements for them, but here are some steps if you want to improve the motion somewhat.

In this photo, we've replaced the plastic bushings on the lower front shaft with two flanged ball bearings (McMaster-Carr # 6383K245). Because these particular flanged ball-bearings have extended inner races on the flange side, we couldn’t place them in the original bushing position between the column supports and the side plates of the enlarger head. Instead we used a pair of clamping collars (i.e. 6435K13) to hold the bearings in position on the inside of the column supports. Because the bore of the flanged ball bearings (1/2") was larger than the enlarger shaft, we inserted a pair of 1/2" o.d. x 3/8" i.d. x 3/4" long flanged bronze bushings ( 6157K13) to serve as a sleeves.

Two drawbacks remain. Because of the gear teeth machined on the rear of the enlarger column, we were unable to inside-mount the flanged ball-bearings on the rear shafts. Plastic bushings remain on our test enlarger. Secondly, the inside mounting of the bearings consumes 1-1/2 inches of the enlarger's downward travel because the bearings contact the enlarger's mounting pedestal at the bottom-most position. This isn't a significant disadvantage for most users. Both of these problems disappear if a suitable flanged ball-bearing can be found from another supplier.