Electric motor frame progress

After a very slow start trying to drill through 5mm thick Stainless Steel I’m making better progress now. Still taking it very slowly to try to avoid mistakes.

In these images you can see one of two Stainless steel sheets used for the front of the motor. I could only source 3mm sheets so I’m doubling them up for better rigidity. Two x 3mm sheets at the front and two more at the back.

The sheets are going to be framed on all four sides by stainless steel angle 30mm by 5mm. Then more of the same 30mm will be used to join all four corners front to back, making an open sided box.

I also have some flat bar to add a diagonal brace to each side.

Then two length of 50mm angle to go across the front and back, sticking out of the sides. This will then be bolted to the 4 flexible engine mounts.

The whole lot is going to be bolted together. Lifting it onto the boat will be easier a bit at a time and it will make any future changes easier.

One of the complications is the belt drive that connects the motor to the drive shaft (to provide the reduction in rotation speed needed to match the motor speed to the propeller).

We need to be able to adjust the belt tension between slack when fitting it and the right tension when running.

To make the alignment to the propeller shaft as straightforward and consistent as possible the belt driven shaft is going to be in a fixed position in the frame and so fixed in relationship to the engine mounts and propeller shaft.

So the motor position itself needs to be able to move up and down within the frame to provide the belt tensioning. That means the end frames need slots for all four motor bolts, at each end. I’m using a bolt (between the top motor bolt and the top frame angle) to provide precise vertical tensioning.

Two things make it more complicated.

First, there is a bulge around the motor shaft which will need a larger slot cutting in the end plate.

Second, the bolt holes on the back of the motor are at 45° from the front. That means there isn’t a single top bolt to lift for tensioning. So I’ll connect the top two with a bar and lift the centre of that.

Anyway, most of the angle lengths for surrounding the ends are mostly cut. I’ve got the first slot cut in the drive shaft end and the tensioning mechanism for the front ready.

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