Atlas makes an excellent O scale F7 model, with a few areas that could be improved. One of which is the rear coupler area. On the prototype F7 there is considerably more of the draft gear visible. For some reason Atlas has decided to leave some of the draft gear off. This piece adds much needed detail while also allowing for the easy installation of a Kadee 743 short shank coupler. The 3D CAD file was created so that the 743 coupler would sit at the correct NMRA standard height….however….as with ALL 3D printing, small dimensional variations can occur. The way this file is printed, if the height is off, it should cause the coupler to sit low. If it does, simply block sand the surface that mounts to the chassis of the locomotive until the correct height is achieved. Also, the outer screw holes of the 743 coupler box will need to be removed to allow the assembled coupler to fit in the mount. The assembled coupler is held in place with one M2 socket head cap screw (not included). The 3D CAD file was created for the M2, however a 2-56 screw could also be used, but might require minor modification to the mount.
Atlas O scale F2/F3 and/or B Units
– This mount has NOT been tested with the F2/F3 or B units, however, it’s very possible Atlas used the same coupler mounting bracket for all the F unit engines, and as such it might fit.
– This mount was designed and tested to work with the 2 rail F7 engine. It has NOT been tested with the 3 rail locomotive. If you decide to give it a try, please let me know how it fits!
– This mount has been tested printed in the Black Professional Plastic as well as Matte Black Steel. The Black Professional Plastic Coupler Mount has been stress tested (coupler/mount attached to 90deg bracket and weight hung from the coupler) to 20lbs without breakage. The maximum tractive force for a single Atlas F7 is 0.875 force lbs. That means this mount can handle 21x what a single engine can pull! If you want an even stronger Coupler Mount, the file optimized for Steel is available HERE
The Polymer Optimized Coupler Mount has an extra centrally located mounting hole if you want to add a little extra strength. It isn't needed and can be cut off if so desired.