Undertail Cover

The Undertail Cover is a flat plate 5 mm thick that goes under the seat of a motorcycle, in place of the stock cover above the rear wheel. That stock cover has a box that bulges downwards. The question was whether it could be straight, so that the line of the tail carries through.

The design. The plate is a trapezoid: 190 mm long, wider at the front than at the rear, with its four corners cut off at 45 degrees. A 2 mm bevel runs around the visible face. Three grooves 8 mm wide and 1.2 mm deep lie in the face, the middle one longer than its neighbours. The plate hangs from four screws, whose heads sit in recesses 2 mm deep. This is the third version. The first was a cover for the tail section, the second a faceted pan 24 mm deep. The flat plate won by trying to be the least.

What makes it hard. The dimensions. They are scaled from photos and catalogue drawings, not measured on a bike. That is why none of the screw holes is round. Each one is a slot 14 mm long that points at the centre of the plate, so an error of a few millimetres in any direction is absorbed. The plate prints with its visible underside on the build plate. That face takes on the plate's texture. At 190 by 221 mm it fits the 256 mm build plate in one piece. PLA is not an option here: a part that hangs outdoors under a motorcycle calls for ASA or ABS, which is ordered per job.

Where it stands. This is a fit prototype. Its job is to be held against the bike, to show where it binds and to correct the drawing. No print report exists yet. The images are renders.

It shows how a custom part starts: with photos, a first fit version and slots wherever there is still doubt. If you would like something similar, ask for a quote.