Saturday, November 5, 2011

Millie - Piston

I had a short session this morning making the piston. It was made from the supplied steel pin which I turned to 0.123" instead of 0.125" called for in the plan. I've to learn to be more careful when creeping up to the required dimension. Hope this 2 thou difference will not cause any problem later.

Turning the piston

Overshot the required 1/8". Measuring after parting off.

The next operation involving the drilling of the 1/16" hole on the cylinder face. I wanted to try using the rotary table to hold the job in the mill. This is to provide the practice I need in setting up. Didn't follow through with this as I couldn't get the face of the rotary table square to the table of the mill. I'll have to learn to square it up at a later date.

I notice a deep cut on the right angle attachment when removing it from its plastic bag. I would feel better if I caused the cut but it has been in the bag within the box it came in since I bought it. Should have notice it earlier.

I parted off the piston 2 thou longer than the required 0.6875" this time do that I can trim off the excess later (I've been going under too often so far...).

Holding the piston in the vise, I carefully touch off a 6mm steel dowel to find its centre and end. The 1/16" HSS drill was then swapped in and drill away.

It was tricky at first when the drill started wondering. Light stabbing movement was used and the drill managed to find its way through the piston. The hole looks centered on the face of the cylinder.

The piston done.

One thing on the crank disc from the previous instalment surprised me a little; the crank shaft was originally a sliding fit in the centre hole of the crank disc. I left it in for the night after taking photos of the assembly. This morning, I can't remove the shaft from the disc anymore. This shows that the heat generated during machine operation does expand the part a little to allow a much tighter fit. Instead of using Loctite to hold the shaft to the flywheel (which no long can be pushed in), I'll heat up the flywheel a little to fit the shaft.

I believe I've completed the lathe work for this project. Will be starting on the other parts which are mainly done on the mill. I'm think of doing that tonight, after my birthday dinner, if I'm not too tired.

I'm sitting at the showflat opposite Katong Shopping Centre at this moment. Time to shift my mind back to work.

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