The Homemade Nav Tower

Adventurising the 500 means making it more capable of navigating and covering some major distances. In order to travel light, I probably won’t be bringing a computer, so plan on either using a phone or tablet to navigate using OSMand.

This setup will eventually be modified to take a Garmin Montana GPS as seen in action in the video below, but for the majority of the post here it’s being built to hold an android tablet. Like everything else in life (myself included) it’s a work in progress.

So how to build it and mount it to the bike?

I already have M5 threaded holes on the handlebar clamps, and a set of RMS rally roadbook clamps from F2R. Combined them should make a sturdy platform to hold my nav equipment, and maybe I could wire up some USB power sockets too..

First things first, I needed to make a cardboard template and cut it to size to see how it might fit on the bike. I was reasonably happy with the size and shape so traced the outline of the shape onto some plate aluminium and cut it to size.

I picked up these cheap USB sockets/voltmeter on amazon, and cut the holes to size using these hole saws.

I wasn’t happy to leave the aluminium completely flat as it would probably get a lot of glare and reflections from the tablet screen,and make the it more difficult to see.. so I measured the width of the tablet and bent the alu plate at a place I though appropriate. Hopefully the angle will be ok and the screen can be seen easily in both sitting an standing positions. I might have jumped on and off the biike a few times while experimenting with the angle here.

Four M5 bolts secure the plate into the threaded handlebar clamps, and another four M4 bolts hold the plate to the RMS’s 12mm crossbar mounts.

The two 30mm holes in the plate will house the USB sockets and a switch to turn the power on/off.

After making the basic frame and mocking everything up, it was time to disassemble it all and prep the plate for painting. This is just basic rattle-can zinc primer followed by cheap satin black. At the same time I cut two channels cut out of either side to assist in mounting the tablet using double sided velcro tape.

Painting complete, it was re-assembled and tested and everything works!!! Hopefully the vibrations won’t kill it.

 

Stopped in Connemara.. The glossy tablet screen isn’t ideal but the ‘night mode’ colour scheme in OSMAnd makes it actually fairly easy to see at a glance on the move, without being too bright at night.

Eventually, I replaced the old Nexus7 tablet for a Garmin Montana 600. It’s better as a pure GPS unit, in that it can follow a track, but it’s useless at rerouting around something. It’s main advantages over the old tablet are that it’s not afraid of a little water or vibration, and doesn’t rely on a micro USB to keep it charged all the time.

Update to the wiring for the Montana (Garmin Amps) cradle, the power switch now controls power to both the Garmin Amps cradle and the twin USB sockets. The wiring comes from the bikes battery, via a 10A inline fuse, to an SAE block connector. The block connector has a waterproof cap and it makes it so that the tower can be installed and removed easily by undoing a few bolts and simply unplugging the SAE connector. Make sure the positive wire from the battery goes to the female end of the first SAE block connector so you don’t create a short circuit if it accidentally touches the frame. The 10A fuse on this section of wire is so that if you do accidentally touch the positive end off the frame and create a short circuit, the fuse will blow immediately and you won’t have a fire risk.

On the nav tower side of it, a 5A inline fuse is installed before the power switch, and then the power switch then controls power to the Garmin Amps cradle and the twin USB sockets. I figure that 12Volts * 5Amps can provide up to 60 watts of power before blowing the fuse. Charging my phone is 5V * 2A so that’s 10 watts used, ok maybe 20 watts if I have to charge a camera battery too. I reckon the 60 available watts should be plenty to charge a phone or two, and keep the GPS going too.

 

 

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