Turbine – Part III

Version 2
Here the end caps slide over the tubing. The line of rivets would be separately applied .. either Styrene (Tichey) or possibly even brass. In either case the end caps would be 3D printed, cleaned up and the rivets inserted afterwards. This would then be a master for making a RTV mold.

Notice that I have also modified the elbow so it has a flange down the center. More on that in a bit.

Spinning the assembly around to look at the outflow side with the elbow. I put a flange along the top spine .. forgot the bottom .. but this was just a ‘quick and dirty’ concept model.
Bits and Pieces
You can see how the two caps fit over the ends of the tubes. These are identical requiring only one master. The front Shaft support and Elbow adapter fit into the holes in the caps. The intake can be mounted in any direction and can be different sizes. The elbow is split in two parts to make casting easier (theoretically like the original) and can of course be positioned as needed.
I’ve been working on the design a bit. I re-worked the front part with the bearing support and the end cap. I removed the bolt heads and put in holes in their place. They are 0.015″ dia which should be fine to work as guide holes for inserting Tichy bolts/rivets. The idea is to 3d print what is needed and add the aftermarket bolt heads/rivets to make a good master for resin casting. That also was the reason for re-working the bearing support – so as to remove under-cuts in the mold.

The center part .. the body of the turbine will be 1″ dia tubing. I still need to work on the back-end where the tapered elbow fits on. Since the idea is to create masters I can use to create RTV molds for resin casting, I can’t directly mold an elbow with a two-part mold. I’m going to create a ‘history’ where the foundry casting the turbine bits didn’t have the necessary equipment to cast the elbow whole either. Instead, it will be a two part casting that bolts together.

I’ve been thinking about the intake pipe that runs into the turbine. I originally used 1/2″ since that was the largest size Evergreen tubing that I had. I forced that by using it to build the Pentock Collar. I hadn’t wanted to change that to a larger size .. but .. need drives. I have some 3/4″ tubing in-route from Plastruct. I think that would be a usable size – while probably not large enough in dia in ‘real life’ but it should work visually.
Inserting the 3/4″ tube into the 1″ tube worked well with a nice collar created. Now .. I have to figure out how to arrange bolt holes around the collar. The problem is that while viewed from the end of the 3/4″ tube they are in a circular pattern – each hole will need to angle toward the center-line of the larger tube. Still .. will be fun to see if I can figure out how to do that in Sketchup.
Progressing …
This is the latest renderings. The majority of the turbine is completed. The only thing left is the support feet and a few add-on items. The only major thing that I may add is a coubled-flange to the smaller intake tube. That would enable me to attach the feed-pipe logically.
Looking from the rear. I still need to create the piece that fits below the elbow .. a tube wider at the bottom where it enters he water to discharge the water.

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