Stuart Oscillator

[David AmbroseParticipant @davidambrose86182]

Machining the standard – where to start?

[David AmbroseParticipant @davidambrose86182]

I've reached the stage where I want to start machining the standard of the Stuart Oscillator, but I can't work out where to start. Logic says that I should drill and ream the crankshaft hole first and use this as a datum, but I can't work out how best to mount the standard sufficiently accurately for this first operation. Any option seems to involve setting up by eye, and hoping for the best. Or do I machine the base, then bolt it to a vertical plate for all other ops? Any thoughts anybody?

[David AmbroseParticipant @davidambrose86182]

So having tried using the crankshaft bore as a datum by gripping the standard on a mandrel, I now know how not to do it.

I bought another casting, and mounted it base-upwards in the milling vice, as vertically as I could. I machined the bottom face, and the four sides, and drilled the mounting holes. I milled the sides of a piece of aluminium, and milled a rebate on one face to take the base of the standard. I then bolted the standard to the aluminium, and can now machine all faces whilst keeping things square.

All part of the learning process.

[Neil WyattModerator @neilwyatt]

Good idea David.

Small oscillator castings are designed to be as hard to machine as possible.

Neil

[Ian S CParticipant @iansc]

David, a small angle plate is a useful thing to have on the milling machine, even a home made one from heavy weight angle iron with the faces machined square after welding a couple of braces across the angle, this clamped down to the table is more secure than your aluminium in the vise. Good work so far, the idea of these things is I think to stretch your ability.

Ian S C

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