With the trial bore completed, measured and measured again, I thought I’d try pressing it in. I put the bearing in the freezer over night, and warmed up the ally in the oven.
The bearing went in very easily and grabbed itself tight when everything came to a constant room temperature. The bearing is reassuring tight, but still runs freely – I’m happy with that. Even Bob said well done!
Onto the rod itself next for the final article. When I’ve got somewhere near I’ll press the bearing out of the test piece. (Or saw it out). As long as I can reliably repeat the process, I’ll have a finished rod 🙂
So far, so good – although it’s a slow process. Getting to grips with a new boring tool and machine takes a while. The tools seem to be working well, I’m getting a lovely finish on the finest feed and the bore size corresponds to the graduation marks.
I’m starting to hate aluminium swarf though, it gets everywhere! I can only take a 25 thou cut, so opening the bore from half an inch to 80mm (3.149") is going to take a while. And when I’ve finished?
I decided not to motorize the handle that lifts the knee. I’d need an enormous motor for starters, and stepper motors don’t go much over 4nm. The weight of the table, cross slide etc. presents the first problem.
The second issue is the handle driving the knee, which exits at an angle (not perpendicular) with no end cap on it. The mill would have to be accurately drilled and tapped, in situ, to mount the motor. Lots of problems to overcome.
Instead I’m driving the quill to achieve my Z axis. I’m limited to 4" of CNC travel, which should be enough. I can also manually drive the Knee. I went for the largest pulley to get the most torque and steps per mm.
Mounting the motor for the Z was a bit of a faff, but I’m there now. Just a case of calibration and fine tuning now 🙂