Cranking It Up

I may be getting the hang of this milling thing. Today I got most of the way through making the crank for the beam engine. This was two setups and more tool changes than it probably should have been but I am pleased with the result. I just need to mill off the back of the part to separate it from the block of stock I used as a handle.

It looks like it should even if it may not exactly match the drawings. I realized that the only things that really matter are that the two holes are parallel, the correct size and the correct distance apart. Everything else is mostly shaping things to resemble the cast part a full size engine would have. As long at things are symmetrical, nobody will notice if the end radii are a bit too large or small.

I also improved my finding of the center of the rotary table by using a new gadget, a coaxial centering dial indicator. This device gets chucked in the mill spindle and you center on the hole while the mill is spinning (at low RPM). This is actually fun as opposed to the usual dial indicator spinning holder that makes you keep having to move around to see the readings.

The other improvement which is much less photogenic was the acquisition of some drill blanks. I used a 3/32″ dill blank chucked in the mill to center up the part on the table center for the second setup so I could round the small end. I previously just used a reversed drill bit and I don’t think it produced as accurate results. The drill blank is both more rigid and has not flutes to mess with the alignment.

One thought on “Cranking It Up”

  1. It’s really, really neat to see that crank in progress photo because it is another moment in my realising how darn little I know about how things are made. It looks like a really neat idea to just cut this from a length of bar or sheet stock then just slice off the crank—in my head I was still sort of thinking of this in a more complicated activity somehow done on lathe?

    This is so fascinating. I love reading these updates!

    Chris

    Liked by 1 person

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