Thinking about castings…

I went to a 3D printing show with a Scott owning friend a couple of months ago to look at the possibilities of using 3D printed models as part of the casting process for development work with Scott barrels and pistons. It was his idea, not mine but it was fascinating. There are various different possibilities: you can make a 3D CAD drawing and then print a pattern from which you then set up to produce castings in a conventional manner, you could possibly print an exact replica of the component you want out of wax or something similar and then investment cast the item such as they do with jewellery. You can also print the actual sand cores, rather than printing the patterns from which to make them. You can use a 3D scanner, either handheld or one that rotates around the component, which will interpret the image into a 3D image from which a CAD file can be automatically produced. It was very interesting, but it got me thinking about how little I really know about casting.
Roger used to have patterns made regularly, not only for his Scott but also on a far larger scale in the context of the family-run, Leicester-based special purpose machine tool company, ‘Moss Machine Tools’, that he used to be works manager/ managing director for.
That company, details of which you can find if you click the link through to ‘Moss Engineering’ at the top of this page was involved in making complex machines for automotive, MOD and other sectors from 1947 to around 1991 when economic conditions forced it to cease trading. I don’t know whether he’s ever cast anything himself but he has significant understanding through having had to work with foundrys and pattern makers and seeing the issues that have to be overcome within those areas.
I realise that I’ve been looking at all this interesting technology to possibly assist within a casting process but I still haven’t any actual experience of casting of any type. I’ve worked with castings of course, and understand a little of the some of the areas that have to be considered; shrinkage, porosity, premature cooling, incomplete filling of cores but have found myself thinking about it more and more and have gone where any self respecting modern would-be self-improver goes to nowadays… You tube.

I’ve seen several casting videos recently but here’s one that I really liked by a guy called Keith Rucker, because of the thoroughness of the explanation of the process. he’s not setting himself up as an expert but he’s doing it and seeing where it could be better. He’s also using 3D printed patterns to make vintage components! I’m not likely to be attempting to cast any time soon, but it’s all part of learning the language and gaining a better understanding at how a pattern has to be made in order to be able to make up a successful set of core boxes and ultimately a successful casting.

2 thoughts on “Thinking about castings…”

  1. Richard
    The ability to make three dimensional CAD drawings (of any complexity) takes a long time to attain, and to ”print” a object from that drawing isn’t cheap–at least in the U S.

    While it is a wonderful way to make parts, how to learn the whole process (or at least how to get that far) isn’t quick, or easy.

    Herb Kephart

    1. Herb,
      I can see that learning the ropes with a 3D CAD program is going to take time. I’m right at the beginning. I’m starting to get a feeling of progress though.. just need to keep on it, which is the tricky bit.
      I don’t know how much it will cost to get things 3D printed here. For the components we’d be looking at (pistons, barrels) there are fairly cheap printers that are capable, size-wise at least. I also know a couple of people that have them, so the main cost would be the material used.
      Maybe that is expensive, I don’t know.
      I’m not thinking that it would be quick and easy to do home casting but I do see that it would be possible and that there would be a great deal of personal satisfaction (and frustration) in the process. I’ve been putting a fair bit of thought into how I’d actually need to first make, and then layer up the boxes and what the cores would need to look like. Seeing videos on people assembling core boxes certainly helps me with ideas about this. I need to have a plan for how the cores will sit (and where) before I can really know what I have to draw anyway. I can’t just look at one thing in isolation. It’s not something I’m doing in the next two weeks.. but it’s a strong interest.


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