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Single cylinder semi diesel

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Four stroke Fred18/09/2021 05:22:43
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218 forum posts
207 photos

4b3ea678-8aca-43eb-9927-2479fa21de0c.jpegThis weird and wonderful sand castle is the core ( and core box) for the inside of the engine.The small shape near the front left on the board is the core for the exhaust port and will be later will be added on assembly to the main body. As can be seen the 3D printer has been working overtime to produce the core boxes. It has taken many hours so far and it is quite gratifying to see this shape appear from the compound boxes. A liberal coating of silicone spray may have helped. This attempt is not perfect and I think I will have another go as I feel I can improve the packing of the sand in one area and it will be good to have a spare. I still have the more difficult water jacket core to make but feel spurred on by this effort.
Fred

Four stroke Fred26/09/2021 01:36:57
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218 forum posts
207 photos

This picture shows the results of some experimentation with the core for the water passage and proves that not every experiment is a success as the sand was not packed into the castellated sections tight enough Packing the core box in its present form proves a problem and a rethink is required to make sure the sand can be packed into all the recessed parts. This core has to fit over the core in the background and makes the space for the water to circulate around the cylinder. I may opt to make the core as two seperate pieces and glue them together but this will entail more 3D printing. While the printer is doing it job it gives me time to continue the design work on the injector pump and also the clutch unit - not much to show but work that has to be done.

Fred.

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Four stroke Fred26/09/2021 01:45:05
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218 forum posts
207 photos

This is the core core box in its present form.

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Four stroke Fred28/09/2021 02:13:07
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218 forum posts
207 photos

This is the first half of the revised core and box for the water chamber and shows the castellated top. This leaves space for the water and the parts in between are for the cylinder head stud location. This was the easier half to make and the challenge is now to make the second half with all the ports spaces and supports.

Fred

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Four stroke Fred03/10/2021 03:18:56
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218 forum posts
207 photos

Development continues with the core for the water passage. I have tried to make this core using the resin sand but due to the complicated nature of the beast time runs out and the mixture hardens before I have a chance of finishing the packing. I am now trying the CO2 process as this gives me more time. The picture shows the packed core box, the plastic bag in which the core box is placed and then the CO2 is added in the form of the Sparklet cylinder and jig. The whole unit is then sealed up and the bag inflates with the CO2 and it is left to harden up. The first time I did this I hadn’t made the mixture strong enough and parts crumbled and so the experiments continue with the hope that I will succeed in the end. The changes in the colour of 3D printed core Cox is a result of continued modifications.

Four stroke Fred03/10/2021 03:19:44
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218 forum posts
207 photos

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Four stroke Fred04/10/2021 07:21:21
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218 forum posts
207 photos

After many attempts and a big learning curve success has arrived at last! After the modifying, painting and polishing of the core boxes I packed them with sand mixed with sodium silicate. The packing is not easy as it has to carried out in a certain order but at least with the CO2 method it gives me time before it is placed in the plastic bag to be gassed. After experimenting I discovered that half a kg of sand and two table spoons of sodium silicate seem to work well. There are sections of this core that are quite thin and also as the sand is fine it does need a strong mix to bind it all together. As the saying goes “ Small things make perfection but perfection is no small thing”. These cores may not be perfect but I am quite pleased with the results so far. The two halves will be glued together and then placed over the main engine core to create the water passage of this engine. The photographs show the two halves and then the dry assembly.

Fred

Four stroke Fred04/10/2021 07:23:41
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218 forum posts
207 photos

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Jon Lawes04/10/2021 07:24:46
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652 forum posts

I'll enjoy your success by proxy; there is nothing quite like the feeling when it all comes together!

Fantastic work.

Michael Gilligan04/10/2021 08:24:15
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18925 forum posts
942 photos

I remain in awe of what you are doing, Fred

… What a superb project !

MichaelG.

Four stroke Fred07/10/2021 08:49:41
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218 forum posts
207 photos

389862d4-db6e-4f99-b041-d92f29dff672.jpeg4bdbdc17-fb35-4f50-b23d-ac6f5d9a883a.jpeg76576ced-499e-4c31-9fab-828c4367e915.jpeg

Four stroke Fred07/10/2021 09:02:59
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218 forum posts
207 photos

Today I made the boxes for casting and then did a trial run to check to see if all the parts would fit together. The patterns came out quite well but there were a couple of places where there was a slight overhang (that I had omitted to see) and the sand pulled out. Modifications to both the pattern and by making small changes to the core box should over come these faults. I will repack the boxes and then cut the runners where the metal flows in and risers that allow gasses to escape and act as a reserve of metal when the casting cools and shrinks.

Fred.

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