4-8-0 Camelback Details

Swing Bolster

Tim Guenther

This casting looks like a real bugger to machine, so I might as well do it now and get it out of the way. This is the part of the lead truck attached to the locomotive frame. The photos tell the story of the steps I used to machine this part.

Iron casting and drawing from Allen models.
I started by finding the rough center of the top boss.
This looks like a “safe” setup. Watch the fingers!
I left as much material as possible for a clamping surface.
Spot face on the bottom.
Interrupted cuts – slow speed; small bites!
Outside edges – take off just enough to clamp on.
Squaring the part.
Using an indicator to make the other side parallel to the first side.
Using an edge finder to establish the center of the part.
Center drill; drill; and ream to size.
By using a mill instead of a drill press, I could get both holes equidistant from the center and parallel to each other.
Machining the sides. I touched off the shaft to keep the hole in the center of the part.
Measuring setup.
Machining the top of the part to size.
Finished part.

This part was a bugger! I spent approximately twelve (12) hours machining it. Castings are always a challenge to hold and the many interrupted cuts require slow machining. I do not own a vertical milling machine. The horizontal mill works well and the dials are accurate. If you have any questions, please leave them in the comments below.

Published by Tim Guenther

2 thoughts on “Swing Bolster”

  1. Hello Tim,
    Very nice work! I enjoy your posting of the methods and setups you use. I am very proud that you are sharing your build with the world. Mike and I hope to do the same with the Berk.
    As I mentioned at the meeting, after the completion of the pavilion, when we develop a plan for the new shop, it would be nice to have a video library of your build and others who provide photo documentation of their project, so we as a club can use it as a teaching aid. It would, I think break the fear for some to jump into using the machine tools we have out there. Even a small project to get them started. Even if it is only machining a cast iron wheel. I look forward to your next post. See you at the makers fair. Dave W.

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