Plywood means to hold shapes
Ireally enjoyed the July 2021 issue of EIM – I particularly liked the article on historic locomotives as candidates for modelling. A picture of the frames of the Bury locomotives, and a section view was included which were fascinating. I have been interested in these Bury locomotives since I was a small boy and have seen many pictures in books, but this is the first time I have seen these illustrations of the internal details.
I loved the Crampton coverage too. It was a clever design and ahead of its time, although it was limited to light trains on low-gradient lines due to having a single pair of driving wheels. It had a nice low centre of gravity though, an elegant design.
Re the workholding article for odd/large shapes (‘An outstanding job” by Peter and Matthew Kenington - Ed) – one very handy tool in my workshop is the humble improvised plywood faceplate. I have attached some pictures of a couple of mine.
The large and small discs are glued and screwed securely together. They do not need to be extremely round, mine are left as sawn. In use, the small disc is placed in the three-jaw chuck in the lathe, pushed up hard against the jaw faces, and the work attached to the face of the larger disc with wood screws or machine screws, set to centre where needed.
They are very useful for trepanning discs from sheet metal and can also be held in the four-jaw, I have done so when boring out sprockets, pulleys or gears where the existing bore must be picked up for re-boring larger.
For holding brake shoe castings as in the EIM article, a few screws through the pivot pin holes, or a few screws and washers next to the casting perimeter would hold the casting nicely to a plywood faceplate. No worries about the tool being damaged with these either, you can see in the pictures of my well-used faceplates that tools have made contact multiple times!
These devices can be made easily and very cheaply in a few minutes, from plywood scraps – whatever is at hand. I have never had one break up in use, but then I usually take light cuts to reduce the risk of the disc pulling out of the three-jaw.