How to Make and Use One-Piece Patterns

[Alyn Foundry]

Here in the UK we use the term’ oddside’ moulding. The moulder would place the pattern onto the moulding board. The pattern would be dusted and then covered in a good layer of Virgin sand. Firmly packed and then backed out with backing sand. The box would then be fully rammed up and strickled off to finish. Upon turning the box over the pattern is located and dug down to. All the edges located and the split line found. The moulder would then smooth down the surfaces ready for preparing the Cope. At this point this box would be used several times to make multiple pieces. A fresh Drag being made each time.

The use of split patterns greatly reduces the time spent moulding and should reduce the cost of the finished product.

 

[Charles Lamont]

Today, if you are sending a pattern out to a commercial foundry it is likely to be expensive to have the moulder do the excavation by hand, and I suspect a lot of foundries would turn down the job. The alternative is to supply an oddside board that eliminates the tricky work. I have shown the idea on the other thread:
https://www.homemodelenginemachinis...g-for-chenery-gnome-rotary.36604/#post-419358

 

[Roger Taylor]

An earlier thread display of old school wooden pattern construction took me back to my metal shop teaching days when I loved to make one piece, split, and match plate patterns. The crash bang 3D modeling methods while expedient, loses the art and craftsmanship part of patternmaking in my way of thinking. I imagine that all of the commercial foundries now days use 3D for their patterns but as an 81 year old, nothing is more satisfying than making the pattern in wood and molding the first parts.

 

[Richard Hed]

An earlier thread display of old school wooden pattern construction took me back to my metal shop teaching days when I loved to make one piece, split, and match plate patterns. The crash bang 3D modeling methods while expedient, loses the art and craftsmanship part of patternmaking in my way of thinking. I imagine that all of the commercial foundries now days use 3D for their patterns but as an 81 year old, nothing is more satisfying than making the pattern in wood and molding the first parts.

I find the same thing in many other feilds. Human beans are MADE to learn thru hands/eyes/ears and the coodinations between them. If we cut all that out, it's like person's missing their souls--all white, no color, no grey. A couple decades back the schools in the US built with no window in the rooms. Naturally, it backfired to my great satisfaction. Book larnin' is good, but lack of non-book larnin' is BAD! More hands on larnin' would be better for students and schools. There would be, for SURE, less dropping out and far less other societal problems.

 

[GreenTwin]

I think students should learn manual machining with a lathe and mill before they learn CNC and associated software/programming.

Likewise, I think folks should make patterns manually from wood in the beginning.

I asked one person who was making patterns for a model engine on ytube why they did not 3D print their patterns, and they said "Hand-made patterns from wood are organic, and that is something that 3D printed patterns do not have".

I have made some 3D printed patterns "organic" so that they look like they are made from wood, and sometimes it is easier to just make patterns from wood in the first place.

I am deep into 3D printed patterns now though, so there is no turning back for me.

This was a pattern I made years ago for a little wobbler steam engine.
I made some of the sides convex so that they looked more natural.
I try these days to add all the fillets, curved surfaces, etc. into the 3D model, so as to minimize adding filler after printing.
.