We received out sheetmetal bracket back from Kia Ora sheetmetal. The engineers there had made it to an excellent standard. In order to keep costs down we said we would cut all holes ourselves. This image shows us testing and adjusting the position and height of our motor bracket and parts.
Damien and Haydn had bought some 5mm alloy sheetmetal earlier in the week. This was probably overkill, when we only needed minimum 2mm to be structurally sturdy. We traded this sheetmetal in for credit on our motor bracket part. All up the motor bracket itself cost $193.
The card mock up of our motor bracket. We gave this to the guys at Kia ora sheetmetal and they made us a 2mm alloy replica.
Hubless wheel design issues
With the CNC router unavailable, and unlikely to be able to cut through our metal anyway, we’ve had to look at alternatives.
Haydn, Jason and I went to Massey’s Industrial Design school and talked to their workshop technicians about using Massey’s waterjet cutter. Nick has a circular piece of lathe alloy to produce the internal ‘hubless hubs’ from.
It would be possible to cut the pieces from a piece of alloy sheet, but not possible to cut from a circular piece of alloy. It would be too risky to use on the water-jet cutter under so much pressure. Materials need to be strongly secured in place and there is nowhere to clamp to weigh down on our piece of alloy.
The Massey technicians suggested other options…
We could produce our shape in polystyrene, then make a sand cast of it, and get aluminium poured into it, melting the polystyrene. This would be cheap, but time consuming.
Rather than having the ‘conventional’ hubless internal wheel shape we could produce another shape that could still acheive our design intent. The conventional hubless wheel shape is a large hollow circle with a small ‘bump’ to fix the axle to.
We could also lathe out our ‘hubless hub’ on the lathe and add the ‘axle bump’ as a separate part later.
A third motor bracket iteration.
This one has a small tab at the front to hook under a special spacer under the front trucks, designed by Jason. This means that this should be able to clip on and off the board.
Damien and Haydn bought a sheet of 5mm aluminium alloy earlier in the week. We thought we could template this motor bracket onto this aluminium ourselves and cut it ourselves. Ideally, a laser or water-jet cutter would be great for cutting this sheetmetal template to precision and we could bend it up ourselves in studio. Advice from the workshop technicians suggested that we couldn’t, especially at that 5mm thickness.
We took our sheetmetal to a metalworking place on Adelaide Rd. They weren’t very happy to produce it for us at a days notice but will consider it. We have a backup plan if they’re too busy. We gave them render images, paper templates and a new cardboard mockup to work from.
A second motor bracket iteration.
This highlighted a few design problems, such as aligning the motor’s heatsink horizontally, ground clearance, length, internal holding space, and allowances for metal bends.
The first motor bracket iteration. The board seen in the photo is just someone elses that we found in studio.
