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Wednesday, 24 June 2020

Project 20 - 0 Gauge Layout - Part 22

4mm version
Regular readers may remember the Crewkerne crane I modelled in 4mm scale (shown right. Click here for details). I like the style of it so decided to upscale it for this 7mm layout.

This should be simple. In theory all I had to do was scale up the .stl parts in my slicer program before 3D printing them. That is true for some of the parts. The trouble is that others are simplistic designs of the prototype for 4mm scale since the lack of detail is not obvious to the eye. In 7mm scale it is more obvious. I had to redesign several parts. Of note are the gear housings, which included solid gears in the 4mm version. In the 7 mm version I designed and integrated the correct spoked gears. However, the cogs were a step too far. Even in 7mm scale they are small and thought to be too small for my 3D printer to form.

I noted in the 4mm crane Blog posting that the ratchet locking mechanism was not modelled (because available photographs did not show the details). Sorry to say that is still the case so it has been omitted again in the 7mm version.

7mm version
Like the 4mm version it is a static model except it can be rotated on its plinth. The model was sprayed with Halfords grey primer and then lightly sponge dabbed with a dirty rust mix of enamel paints.

The plinth is card with decorative overlays in the manner described earlier for the office building and the railing posts 3D printed with galvanised wire threaded through.

The platform is larger than I estimated. Unfortunately, it has to be placed right on the edge of the quay wall to allow trains to pass by without interference.

I needed to obtain a chain for the hoist. I spent some time searching ebay and whilst there were many available very few suppliers gave full dimensions of the links. In fact only one did and that was slightly too wide for the pulley I had designed. I wondered how difficult it would be to make one. I Googled it and came up with a video tutorial that showed how to make a chain from twisted wire. The trick is to open out the loops with a scalpel to give a fair representation of chain links.

To Part 23.

To Part 1.  

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