Bushed

I have been continuing sporadic work on the beam engine with today being a relatively quick wee part: a bushing to hold the crank shaft onto the crank. Given that this part was about 1/”8 in diameter and 5/16″ long, it is one of the smallest things I have attempted.

My ML7 lathe was supplied with an excellent ER25 collet set that mounts directly on the lathe spindle. I thought it would be useful but I am still growing in appreciation of just how much. Holding onto the 1/4″ round brass bar I started with was no problem but niether was holding the finished 9/64″ barrel so I could turn off the remains of parting off. And, as is the special property of collets, it did so concentrically as far as I can tell. Which is just as well since I needed to finish reaming out the center hole from that side.

I find this especially exciting since this is getting into the range where I could turn bushing, bearings and the like for 1/4″ scale railroad models if I need to.

2 thoughts on “Bushed”

  1. When making a bushing does the length (depth) of the bushing or the thickness of its sidewall matter? As I start to wade deeper into my 16mm scale curiousity I was thinking about those kinds of questions. Seeing your example reminded me. I used to think the question was just matching to the axle diameter.

    Chris

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    1. You are definitely probing an area that I am wholly inexpert in. I have an entire small book on bearings that I have not yet opened. Nevertheless, the solid bushings and bearings I have encountered see to be at least as long as the shaft going through them. Wall thickness probably has a minimum but it could be very thin. I suppose it would depend on expected load, heat generated, wear, etc. I can’t imagine anything but wear mattering for a 16mm scale model.

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