In my recent GPS mount threads, the issue of security came up. The Zumo 396LMS I use doesn't have any, and I've not seen any commercially available locks for it. Oh well, let's get to making something.
So the 396 has a button on the bottom you press which slides out a piece on the right side that unhooks the GPS. If I could cover the button or stop the moving bit it can't be removed. It was easier to stop the moving bit. On a side note, the 396 has wifi built in so there's really not a good reason it has to come off the bike, ever. You can update it, update the maps, transfer tracks and whatnot without a direct cable connection.
I started by grabbing a whunk of aluminum extrusion I've had laying around for years colored it with a sharpie and laid out some general cut lines.
Untitled by Uncle Grr!, on Flickr
Then I laid into it with the milling machine. Most work was done with an 11/16" two flute end mill because that was my sharpest one.
Untitled by Uncle Grr!, on Flickr
Note that this was made more on kind of a general idea than a plan and was intended to be a proof of concept. If I liked it I'd make a better one.
Many hours of milling and a colossal amount of aluminum chips sprayed everywhere near the mill this is what I ended up with.
Untitled by Uncle Grr!, on Flickr
You can see in this one that I had some pretty sketchy work holding and it let go once, leading to some pretty big divots in the part. Good thing it's on the back side.
Untitled by Uncle Grr!, on Flickr
Installed enough to test.
Untitled by Uncle Grr!, on Flickr
This is a bottom view. The gap between the two parts is exactly how much is needed to remove the GPS.
Untitled by Uncle Grr!, on Flickr
And here it is with a screw installed in the tapped hole. It's tapped M5, and for testing purposes just has a regular shcs installed. I have a box of security torx screws on the way that will be installed.
Untitled by Uncle Grr!, on Flickr
And now we have a quick interlude from Webster's dictionary. Machining is a process of removing material until you get the shape you want. Liken it to carving a boat from a log. Fabricating is a process of adding chunks of material till you get the shape you want. Liken it to building a model.
Because the first mount I made was done possibly the most difficult way possible this side of miracling it out of thin air, I figured I'd see if there was an easier way.
I grabbed one of the spare GPS mounts I made a bit ago and pondered heavily while drinking a beer and scratching my head. Then I went to the scrap pile. My neighbor had given me some shelves that were held up with a bent 1/8" stainless bracket. I cut it apart, bent it to fit, tapped to M5 and welded it to the mount plate.
Untitled by Uncle Grr!, on Flickr
Untitled by Uncle Grr!, on Flickr
End result, exactly the same. Effort required, nearly none comparatively. Sometimes machining is called for, sometimes fabricating is called for. Sometimes it's fun to do both. Both brackets are now in paint, and when they're dry I'll decide which one is going on my bike and the other will go on the shelf as a spare.
I'll update once I get the screws and get it installed.
Edit: I don't know why those last couple pics make it look so crooked. It's not.
So the 396 has a button on the bottom you press which slides out a piece on the right side that unhooks the GPS. If I could cover the button or stop the moving bit it can't be removed. It was easier to stop the moving bit. On a side note, the 396 has wifi built in so there's really not a good reason it has to come off the bike, ever. You can update it, update the maps, transfer tracks and whatnot without a direct cable connection.
I started by grabbing a whunk of aluminum extrusion I've had laying around for years colored it with a sharpie and laid out some general cut lines.

Then I laid into it with the milling machine. Most work was done with an 11/16" two flute end mill because that was my sharpest one.

Note that this was made more on kind of a general idea than a plan and was intended to be a proof of concept. If I liked it I'd make a better one.
Many hours of milling and a colossal amount of aluminum chips sprayed everywhere near the mill this is what I ended up with.

You can see in this one that I had some pretty sketchy work holding and it let go once, leading to some pretty big divots in the part. Good thing it's on the back side.

Installed enough to test.

This is a bottom view. The gap between the two parts is exactly how much is needed to remove the GPS.

And here it is with a screw installed in the tapped hole. It's tapped M5, and for testing purposes just has a regular shcs installed. I have a box of security torx screws on the way that will be installed.

And now we have a quick interlude from Webster's dictionary. Machining is a process of removing material until you get the shape you want. Liken it to carving a boat from a log. Fabricating is a process of adding chunks of material till you get the shape you want. Liken it to building a model.
Because the first mount I made was done possibly the most difficult way possible this side of miracling it out of thin air, I figured I'd see if there was an easier way.
I grabbed one of the spare GPS mounts I made a bit ago and pondered heavily while drinking a beer and scratching my head. Then I went to the scrap pile. My neighbor had given me some shelves that were held up with a bent 1/8" stainless bracket. I cut it apart, bent it to fit, tapped to M5 and welded it to the mount plate.


End result, exactly the same. Effort required, nearly none comparatively. Sometimes machining is called for, sometimes fabricating is called for. Sometimes it's fun to do both. Both brackets are now in paint, and when they're dry I'll decide which one is going on my bike and the other will go on the shelf as a spare.
I'll update once I get the screws and get it installed.
Edit: I don't know why those last couple pics make it look so crooked. It's not.