Maine Central #470, the largest surviving steam locomotive in New England, has a new part. I was given the opportunity to make replacement handrail stanchions for the tender, the ones that remained had pretty much been rendered useless by vandals or rust. So, long story short, I used about the only intact one left and made a new pattern based on it. Today I made the first attempt at pouring them in cast iron. I had one success and one short poured because I spilled a little bit of iron on the first one. Only 11 more to go! Only need 10, really, but spares are always good...
Just a minor correction, the casting was done yesterday, I had a few issues posting it last night. Also, I tried the pouring basin and sprue setup from Oldfoundryman's youtube vids, it more or less worked as advertised, and I'm kinda shocked that this large of a casting fed perfectly fine from that small of a sprue. Food for thought.
Looks like it came out very well. 11 more to go?? Sounds like a busy week How about a picture of the engine itself. I'd love to see what your working on...
All kinds of pics at www.newenglandsteam.org . For something that nobody thought would ever get done, a lot of amazing progress has been accomplished. The tender was the first thing to really get tackled, and it should more or less be completed this year. They had to have a new body fabricated for the tender, because 70+ years of decay and neglect sitting in a park turned it into steel swiss cheese. When all is said and done, I should have quite a few parts from my foundry on it. Oh, it's around 8" or so long, the bottom is around 2" diameter.
All cleaned up, with the gating the entire casting weighed in at 9 lbs 2 ounces. Pretty cool to think that in 50 years it will be practically indistinguishable from the originals. On to the rest!
That is a nice casting. It has a good surface finish. Does it machine well, or has it been machined yet?
Very nicely done! What did you use for core material? It looks like the horizontal part is cored anyhow. I suspect the vertical is too. Pics of your pattern, core box, and a couple more views of the casting would be of interest, if you don’t mind. Is the square splash basin actually a filter? Denis
Thanks for the compliments, guys. Dennis, no real machining necessary, the only thing that it needs is a hole drilled and tapped in the base for the bolt that holds it down, and I suspect the core of the main body is not hard, when I broke the riser off the fracture was grey, with none of the shiny flecks that would indicate ( to my eye at least) white iron. I also waited an hour and a half or so before I shook it out, it was still warm, but it had a more gradual cool down. As far as surface finish goes, I sprayed the mold face with graphite before I closed it up, I bought an actual vintage foundry sprayer off fleabay years ago, I'm happy I did. Melter skelter, I have vids up on my Facebook foundry page ( just search for Odd Duck Foundry) of making the corebox and cores. The body isn't cored, it's solid. It's a pretty simple part, really, and the original was kinda crude, really. It still had casting flash on it, and evidence of the ingate, which is how I figured out the gating for it. No filter, not really a "mission critical" or heavily machined part. Dunno if the basin at the bottom of the sprue was strictly necessary, but I don't think it hurt anything. Perhaps HT1 can chime in with a critique of my gating...
Two more done today, would have been three but I think I poured just a little bit on the cool side, not by much, however, because it almost completely filled. 9 more left!
How much contact does the riser have with the end of the part? Given its size I'm surprised it remains molten long enough to function correctly, but it evidently does. I poured an item in iron recently of similar mass (lathe compound slide) with a very large blind riser between the runner and casting and the riser didn't function at all resulting in pretty massive internal voids in the casting. I'm still at a loss to explain it. In contrast I also poured a link arm using the same riser pattern in the same orientation and it worked perfectly. Weird. Pete
I’m going to take a stab at answering. We’ll see how far off I’ll be. Please go easy on me if this is all wrong. Duck’s riser is attached to the most massive portion of the part. That location plus the mass of the riser makes it likely the riser-end of the part froze last and so the riser had a chance to work. Hopefully he had a fairly thick contact between the riser and the part. I also was wonder how thick the connection between riser and part was. On your slide, the center of mass/heat is likely more or less the near the geographic center of the part and perhaps offset slightly toward the riser. That is probably where it froze last. So, I’ll take a chance and guess there was a vacuum defect near the geographic center of your slide. If that is where the defect is, a riser directly in contact part there would make that the last section to freeze. The top of the riser could collapse and likely no defect. On your link the most massive part is the large end of the link where you placed your riser. The larger cross-section plus the riser’s heat encouraged that area to freeze last and so the riser worked. Denis Added: All that "wonderful theory above in this post aside: I find risering tricky and not entirely predictable. Here are a couple shots of a part I have cast many times. If I cast two oriented pointy parts to the outside of the pair, no riser needed. If I cast them point parts next to each other without a riser, I get a contraction defect where the risers are. You can see how much they fed.
I was very concerned about shrink on the fat end of this casting, my experience with iron ( so far...) has shown me that it's shrinky. So, on this one I placed a cold riser on that end, it's gated on the cope side, fairly close to the part, roughly 3/8" away. It's bigger than the ingate, I wanted to make sure it worked. It does, I'll try to get pics of the top of the riser to show. I could see it feeding back in before I put a brick over it to keep some heat in.
Here's a better pic of the risers, the one on the left in the first picture is still attached to a failed casting. Pissed me off, it looked like a good pour, on post analysis I think it was just a bit on the cold side, so the handrail part didn't fill completely. Anyhoo, the riser in the middle was the first set of molds, used a straight dowel. Worked okay, but I moved to a tapered riser to try to keep more mass down by the casting. Did it work better? No clear evidence, but the shrink cavity difference between tapered an non tapered might be an indication. And, to try to get a better idea of what happened, I cut one of the tapered risers in half lengthwise. No voids, but check out the depth of the shrink cavity on top, so something happened.
