In the past, the P/N 520 gearbox has been made as a casting of 356T6 aluminum, then machined for the bearing bore and assembled with bearings, shafts and gears.

We are now making this part as a machined part from a single block of 6061T6 aluminum. This is only possible with the machining centers that are now available.

So let's show you this whole process.

We start with the solid blocks. These are castings which are dead soft, then forged into the blocks you see here with a giant drop hammer. This gives the shape of the blocks and work-hardens the aluminum to the T6 condition. Now it's a very strong block of aluminum without any voids or imperfections.

Which then goes into the machining center.


... and the first face is machined.

Which then completes the first stage.

Now we have a fixture to hold this part for the next step of machining.

And here we go hogging this up.

... which gives up this.

Note that the holes are drilled and tapped to secure this to the fixture.

Here's the fixure in the machining center.

Now it gets milled into shape and with bearing bores.

It's not enough to machine the bearing bores. The cutters leave marks, so now we use a roller burnisher that smooths the inner bores to a polished surface.

There are some holes to drill.

Giving us parts that look like this.

Let's check that the retraction motor assembly fits, and of course it does.

Parts will be available from Gunder soon. There is a limited supply, so get your order in.