Handlebar controller

The task this week has been to replace my original handlebar controller (which was bodged up from an old remote control) with something a bit tidier.

Enclosures

Being a one-off, any sort of custom housing was out of the question (except possibly 3D printing), so my first port of call was browsing through small plastic enclosures at Mouser & adding a couple to my last order. Here they are lined up with a Garmin 705 for scale.

enclosure1

enclosure2I decided to start with the enclosure next to the Garmin, (a Bud Industries HH-3641), which I drilled and fitted with some cheap & nasty panel mount push buttons from eBay. It has a bit of a stealth look at the moment, but luckily I know which buttons do what! In due course I’ll likely get a vinyl sticker printed up for the panel.

The keyfob on the left probably deserves a sidenote here; I’m not so keen on the extra wires hanging off the bars, so am planning to make a wireless version of the handlebar controller in due course. However, this feels like an unnecessary distraction and expense just now, so  will come later as an ‘optional upgrade’.

Anyway, one of the wireless chipset manufactures sells pre-built keyfobs that look identical to this (empty) enclosure, so I picked one up to check out the form factor. To be honest, although it’s probably the cheapest wireless option, I’m not convinced – I think the buttons are just a little too closely spaced for my purposes..

Bar mounting

With the enclosure finished, I turned my attention to fixing it to the bars. I toyed briefly with the idea of getting a replacement base 3D printed with an integral attachment point, but I felt this would have slowed things down too much at this point.

So instead I looked at hand forming a moulding to mate with the bars. I wanted it to be easily removable, so decided on a curved form to match the profile of the bar, held in place with an o-ring or elastic band.

While looking for some sugru (mouldable silicone), I came across some polymorph plastic on eBay, so went with a 250g bag for just over £5 delivered.

poly1

This plastic has the property of softening at around 60 degrees C, where it can be easily hand shaped, and then hardens to a nylon like finish as it cools.

poly2I put a handful of the plastic granules into a pan of hot water (at around 70 degrees) until they softened and turned transparent. They could then be fished out (they clump together naturally), and shaped into a block with a spatula. The plastic retains it’s flexibility for a good few minutes as it’s worked, but can just be re-warmed again and again until reaching the desired shape.

As a one-off, I hadn’t bothered making any sort of mould for the design, so I just shaped it by hand until I reached a result I was happy with.

Then another quick reheat and I placed it onto the enclosure, where it stuck like glue as it cooled. Not a straight line in sight, but am pretty happy with the results.

poly3

And finally, fitted to the bike. The plastic was quite slippery against the bar, so I used a strip of tape on the underside to stop it twisting with button presses.

enclosure3

Coding

With some working buttons once again, I was able to fix up some outstanding firmware bugs and test the new offline / manual mode that allows for resistance control from the bar controller when not being actively controlled from the PC..

Next week, it’s the turn of the motor and electronics to get moved into a new enclosure.

Advertisements