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Base
The next part cast was the baseplate. I needed to modify my larger flask by adding corners because I didn't have enough greensand. The pattern used 3/16 plastic lettering purchased from a plastic model supply site. Swept a compass across the painted surface and estimated the spacing first. Then laid it out with tweezers and finally glued in place one letter at a time with white glue. I am glad I waited until I had painted and smoothed the wood patterns as these letters don't stick up that much. I waxed and buffed to help pull the letters from the sand. The Esses are a little messy, but its legible. I always admired how other people did this on their models. It adds a lot of realism in my opinion.

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I gated into the bottom surface so the tapered edge would be preserved, and placed 1/2 & 3/4 copper risers on the two thickest bodies to compensate for shrinkage. I barely had enough in the crucible (lucky). I will definitely need my larger ones for the next two parts, the Flywheel and Cylinder. There are some indications on the cylinder mounting pad that I hope are superficial. 😕

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Base
The next part cast was the baseplate. I needed to modify my larger flask by adding corners because I didn't have enough greensand. The pattern used 3/16 plastic lettering purchased from a plastic model supply site. Swept a compass across the painted surface and estimated the spacing first. Then laid it out with tweezers and finally glued in place one letter at a time with white glue. I am glad I waited until I had painted and smoothed the wood patterns as these letters don't stick up that much. I waxed and buffed to help pull the letters from the sand. The Esses are a little messy, but its legible. I always admired how other people did this on their models. It adds a lot of realism in my opinion.

View attachment 156845

I gated into the bottom surface so the tapered edge would be preserved, and placed 1/2 & 3/4 copper risers on the two thickest bodies to compensate for shrinkage. I barely had enough in the crucible (lucky). I will definitely need my larger ones for the next two parts, the Flywheel and Cylinder. There are some indications on the cylinder mounting pad that I hope are superficial. 😕

View attachment 156846View attachment 156847It's coming on really great.!!
 
thank you again for the encouragement!

Cylinder
This is a large part for my experience in sand casting. It will require my largest flask, additional sand, and a real core for the bore. I purchased 24 lb of new foundry sand. It feels much sharper and bonds better than the other sand I have.

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I used it to make the core. The core pattern is just a slit piece of 1-1/2 plumbing PVC pipe. Needed to place hose clamps around the PVC to prevent spreading and increased diameter. I also reenforced the sand core with a piece of TIG wire so I could handle it. This must be the absolute limit of an unbound sand core as it cracked , but held enough to work.

The first attempt failed miserably though as molten aluminum seeped out of the bottom somehow. Very glad I had lots of dry sand underneath to catch the spill or I would have been replacing part of my paver driveway. :oops:

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I couldn't really tell why this pour failed, so I tried again without doing anything different. This attempt was not 100% perfect as it appears to have had some loose sand in the casting on the bottom mounting rim. Hopefully this can be filled in with epoxy as it appears to be limited to the circumference only. It is so terribly hot, 97F with 47% humidity, during the afternoons here in central Florida right now, so I decided to call it a day. I had exhausted my propane tank anyway.

I plan to get an early start on the two legs tomorrow.

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Legs

these patterns require digging out the sand to an imaginary split line. I had some practice several weeks ago, but ran out of sand so didn't make the pour. The first pour was terrible. I really think the big difference in success so far is the professional parting powder. But improper gating and venting will still ruin a cleanly released mold. I believe I connected the vent or riser below the topmost part of the casting and steam blew out the corner.

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So I added one more vent and moved the risers towards the top. I also poked a few vent holes with a bit of wire. I may have started straying towards the damp side with the sand. The next two legs (left side) came out nicely and should clean up well.

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Flywheel

the curved spoke pattern was a special challenge for me. I approached it by using an online flywheel simulation, clipping an image, and then printing out a paper pattern full-size.

https://rawgit.com/tinglett/MachyTools/master/FlywheelBuilder.html#spoke
curved spoke flywheel.png


I then cut a single pie shape out of 1/4 plywood using a scroll saw and sanded the inside cutout carefully. This sector pattern was then indexed around an MDF center piece and traced. The center piece was actually two thin pieces held together by painters tape.

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Cut each opening roughly using the scroll saw again. Then used a flush cutting router bit to trim out the six identical shapes. But I still needed the rim widths added.

I rough cut two circle blanks again which were fastened to a wooden faceplate to taper the inner and outer diameters. Tapered dowels were cut for the hubs and glued on.

Painting the MDF raised grain several times before becoming smooth. Finally some fine abrasive pads and paste wax made them smooth enough to use.

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