Copyright WWW.DBBP.COM | updated 31-January-2013

My BMW Bobber, part 85
CAD version here


Last week we cast 6 battery covers, these will be machined into 3 lower and 3 upper covers. After machining off the excess material we used the old analog Bridgeport milling machine to find the center of the first cover and then to hollow it down, writing down all the coordinates of the corners so the next five covers could be machined faster.


The top covers will need a cutout where the battery cables will come out, the bottom covers will need a flat spot where they can be mounted on. After machining the covers all the high spots were sanded and then polished, the low spots between the ribs were deliberately left rough. After all, we certainly do NOT want these parts to look like they were CNC machined!


The batteryovers fit Antigravity batteries, both the 12-cell and the 16-cell. These are very small and light batteries but strong enough to electric start even the biggest V-twin. In this case they only need to start a 900 cc BMW. Next week we will make a cover for the sides of the battery.