Mamiya 645 replacement crank arm and faceplate

thingiverse

This is a replacement for an existing "bakelite" faceplate and/or aluminium arm for the Mamiya 645, and is intended to replicate the original as far as is possible. It has not been tried with the factory made arm, although it should be dimensionally appropriate. Prep: Remove existing faceplate by carefully peeling back the vinyl (faux leather) semi-circular covers on the crank case (a modelling knife worked well for me). They are just glued in place and beneath you will find six screws. Undo the ones at "10 and 4 o'clock (see photo) and the faceplace will lift off. Keep the screws and nylon washers to one side and then proceed to remove the remaining four bolts which hold the simple spring and arm retention mechanisms in place. Keep all bit safe for reassembly later. Parts Required: Faceplate and arm: STL files printed as required For arm: Threaded brass heated insert (M2x4x3.5mm) https://www.amazon.co.uk/uxcell-Knurled-Insert-Embedment-Assortment/dp/B07R4N4X6K/ref=sr_1_47?dchild=1&keywords=m2x4x3.5+threaded&qid=1620589092&sr=8-47 Handle: M2 bolt (14mm) M2 washer 4x Micro ball bearings - MR52ZZ (5x2.5mm) https://www.wychbearings.co.uk/mr52zz_miniature_bearing_shielded.html After printing, insert heated thread and thread the arm though the lower side of the faceplate before reassembling the spring and arm retention assembly, and then putting it back into the crank case. The handle can be attached then by loosely threading four bearings onto the M2 nut, followed by the washer and screwing into place at the head of the arm. re-glue the vinyl back into place once you are happy the mechanism is functioning.