there is every chance I'm going to drop part way into an existing one and produce an odd-shaped over-size hole. So a new backplate for my proof of principle wheel is a must. The old ones vary in size but the new one I made yesterday is only two foot in diameter, which is smaller than I usually use.
Normally I make the backplate much bigger to allow for alterations to the size of the mechanisms and the number of them and their range of movement but in this new one I don't need such a large backplate. The material I use for the mechanism is mild steel and I am able to use and reuse this over time. Obviously the parts get altered and reduced in size in some cases, but because the new design is so similar to the one I last used I don't need to alter it much, so some parts are exactly the same. Because of this I know exactly how big to make the backplate because I have the existing arms and I can plot their range of movement precisely and fit them into an area whose size is also known exactly. This can be one of the difficulties in designing and building something from scratch, you have to use a certain amount trial and error, in part, to discover how big to make it so that it will not come into conflict with other parts and at the same time, keep the range of movement within the confines of its selected area.
So today I was hoping to mark out on the backplate the positions of the various holes needed to support the mechanisms, drill and fit the supporting posts and try to make one working mechanism which performs at just the right moment and in the right way. Because once I have one of them acting in the desired manner, its just a case of copying the same for the other ones.
That was in theory! In fact I had other calls on my time so I didn't quite get that far today.