Budget Q85 Drive

The newer Q85 brushless drives are fast becoming a popular method for powering a droid, replacing the more standard brushed scooter motor (tho of course, we’re builders so anything goes at the end of the day). The main problem with the Q85 motors tho is that they are rather a lot larger and it can be a hard task to fit them in the foot shell.

The Q85 drives are hub motors, this means that they’re all self contained and the whole motor spins. They are designed for converting a standard push bike to an e-bike so need some modifications to work with a droid. Mainly these are freezing up the clutch so they can go backwards, and trimming the rims down where bike spokes would fit. Thankfully the instructions for various methods to do this are covered on the main forum and also this very handy video:

Once they’re modified, the fun is then fitting them into a foot shell. There are a few options by some club members, but these can be a bit expensive, especially for those outside of the states. This is why I decided to have a go at doing something.

For standard brushed drives there is a system called Scavenger Drives, and I wanted to follow the ethos behind these which is to make them accessible to any builder with limited tools. Especially no speciality tools such as welders. My idea is to use a set of easy to cut plates, bolts, spacers, and little else. And this is what I came up with:

This is just my prototype and there are some amendments and fine tuning still to do before I release the files. First of all, the motor does ride a bit high, so I’m probably going to trim about 10mm off the height there which also means moving it backwards to maintain clearance with the hose fittings.

There will be a single omni wheel at the back for balance.

The plate on the outside of the drive should also ideally be tapped so that you can get rid of the nuts totally which can interfere with the footshell. I was always going to do this but forgot when I was drilling the holes for the prototype.

I also need to make a gap for the motor cable to get back into the center of the foot shell so it can be passed up through the channel as this is the most likely place people will want it.

All in all I’m quite pleased with it. I’m going to get a set of plates professionally cut once I’ve done the tweaks, to see how that goes and get an idea of cost. Ultimately tho, anyone will be able to print out the plans, glue them to some 5mm ali sheets (or thinner, especially if they go steel) and cut them out with hand tools, substituting money for time. With the sheets cut, its just a matter of drilling some holes and tapping a few of them, and you have a drive system. The spacing between each sheet is pretty much up to the builder, with just the total distance being a fixed dimension.

Its taken me a while to get to this stage. Not because its difficult, but just time/motivation, but the end is in sight and I really want to get droid 2 finished!

This Post Has 2 Comments

  1. Craig

    Great work. Have you refined the files yet for distribution?

    1. dpoulson

      I have refined them a bit, but not had chance to get another set of plates made to test the final (hopefully) version. Too many projects. 😉

      I can send you the files I have so far if you’re interested in having a look?

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