Pattern puzzle: propellers

propeller1 Today I’m writing about an idea that has been egging me on (“do it, do it”) for weeks so here it goes  -keeping in mind of course that I’m someone who gets a gift book in the mail (thanks Valerie!) about structural box designs and my spouse grins and says “oh, a Harlequin Romance novel for auties”. Yes, this pattern puzzle is about how a pattern is made for a boat propeller. You have not lived until you’ve learned how to make a pattern for these babies.

Like apparel, the process of manufacturing boat propellers hasn’t changed in 50 years. The designs may change but not the process. This affords the advantage of a lot of institutional knowledge.

There are two basic kinds of propellers, a fan (aviation etc) or a screw such as for boats. Never thought about it but it makes sense; screws have to go through other materials be they wood or water. Each blade of the propeller is the equivalent of a screw’s thread. Never thought about that either. Boy, we’re learning all kinds of things today.

propeller2 Due to the dimensional nature and metal casting requirements of the blade, the first pattern (“muslin”) is made of wood. The various layers of wood are cut on a band saw and glued together to shape (above photo). Once dried and glued, the edges are cut and sanded away to create a smooth shape (right).

propeller3 Once sanded and the small holes and scratches are filled in with wood putty, the blade is painted. Like apparel patterns, wooden blades are also color coded to signify the type of metal (material) that will be used to make the blade. Isn’t it interesting how similar concepts are applied as standard practices across diverse manufacturing industries? You can read the whole entry on blade pattern making if it’s interesting to you.

The blog is pretty interesting, some things are the same as in our industry but some are different. For example, in metal forming, it’s better that the machine service supplies materials. Who knew? I also found it amusing that they posted Pantone’s color of the year. Jeez, I meant to do that already, pretty bad that a machining blog outclasses me on such a topically fashion item. So much for me being some kind of fashion expert. By the way, the color is Turquoise 15-5519. Considering that, I suppose it’s not a coincidence that Native American influences are forecast in trend reports. By extension, that would include southwestern styled stuff. I’m happy because this left leaning vegetarian rabble-rouser specializes in all things cowboy & indian. Oddly enough, it’s never bothered my customers, makes me more colorful.

I’ll be out of the office today meeting with a retail VIP who invited me (!) to lunch. I’m excited, maybe I can tell you more about it later. After that, it’s back to sewing. I’ve been cutting patterns for leather bags and sewing a lot of them lately and am not ignoring anyone. Just busy.

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  1. Beth says:

    I also love packaging books. Some come with a DVD in the back for printing out the patterns and scaling them up and down.
    The Packaging Designer’s Book of Patterns by Laszlo Roth and George L. Wybenga.

  2. Adon says:

    Thanks for posting this Kathleen. Glad you enjoyed the article! I also find it interesting the similarities in our industries. I guess both patternmaking industries aren’t as different as I once thought.

  3. Fascinating. So glad you distill this for us so we can just get the highlights!

    Well, who knew about turquoise. It’s one of my spring 2010 colors, so I’m actually ahead of the trend. Wonder if that’s good or bad.


  4. Lisa Brazus says:

    Kathleen it is amazing how similar industries really are. My father was a plastics engineer for the auto industry and I used to listen to him when I was young and it is so cool how they do patterns for cars and car parts. He also has a charter boat and would love to read about how they make propellers.

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