Creating Replacement Members for Steam Shovel Boom

Last Updated on 19 August 2023

For a couple years my dad has been working on a Thew Type-O Steam Shovel from the early 1900s (you can read more about it HERE). Today I was home to help replace some of the structural components of the boom. These pieces were severely eroded after being under water for almost 100 years and were deemed unusable.

The rivets that were holding the eroded pieces in place were torched out. You can see in the picture below that the pieces were missing substantial amounts of material. The pieces were constructed from 6″ channel iron (c-shaped). The key things to do were to cut the pieces to length, create the hole array, and cut a few angles out of the side.

The 6″ beams were cut to length using a horizontal band saw. Dad’s pretty big on using cardboard templates, so that’s what we used to transfer the angle cuts out of the two pieces. They were cut with an angle grinder & cutoff wheel.

The boom still had remnants of old rivets left, so they were cleaned up with a torch. These holes had to be reasonably clean at this point because they are being used to transfer the hole locations onto our new piece.

The new piece was clamped to the book, and the hole locations were transferred using and appropriately sized center punch. A wise thing that dad suggested was to also take a pencil and mark the circumference of the holes before we unclamped the piece, just in case one of the hole centers wasn’t marked properly.

The holes were drilled using an interesting tool: a mag-drill. It has a pretty strong electromagnet that essentially binds it to your work piece, holding it reliably in place while you’re drilling.

An interesting note on the efficiency of this tool – it has a spring loaded center locator that fits well into the hole centers that were previously transferred. So as you move the drill, it essentially “clicks” into place and makes alignment a breeze.

We also recreated this large 12″ channel iron piece using similar methods to the previous piece. Another interesting thing I noted while taking measurements for this was that everything was that across all of the dimensions, the smallest fractional component was half an inch. Meaning dimensions like 56″, 5″, 4″, 1 1/2″. Back in the day it probably would have been more annoying to work with any smaller more precise fractions, whereas today, so much manufacturing is automated that all sorts of funky dimensions are easily achievable.

It’s days like these that make me sad that I live so far away from my folks. This is a fun project and I wish I could spend more time hands on.

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