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Thread: Re-engineering a plant stand: a geometry/math/engineering challenge

  1. #1
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    Re-engineering a plant stand: a geometry/math/engineering challenge

    A lady wanted a plant stand. Sounds simple enough. She gave us this photo:
    F851EB6C-EB39-4F8C-A3A7-6A1FBF1EC291.jpg

    Look closely at those miters. They land on a crossmember, but not all of the crossmembers are supported. This did not seem right, so I looked something similar up online, and yep- they have mitered edges with a crossmember, and no support under some of the crossmembers.
    E1B89644-0629-40C3-B4D3-1DA875A3BD23.jpeg

    How does that middle shelf hold a plant on those mitered pieces? It makes no sense. Also, that thing looks pretty flimsy. It needs to be “Malcolmized.”

    The lady wanted four shelves, and for it to be 48”x35.5”. I am not sure why 35.5 and not 36, but that was the order. I sat down with my students and we re-engineered the thing to have supports for all the miters. We built a 90 degree frame, and then three ladder supports at 22.5 degrees each. We drew the thing out on the table and laid up the shelves on the drawing, and then used that to line up the legs as well. (This gave them a better visual and helped me better explain all the miters.) Two crossmembers held the legs at proper angles.

    Here is the layout
    3DFBD2CF-4A31-49A6-A1BB-96BBB6E8DA8F.jpg

    Here is the finished product
    3C5D0595-EE67-4BAF-88CD-33AA607D0CE3.jpg

    It isn’t as heavy as it looks. One person can pick it up, but two are needed to carry it just because it’s so awkward. This was a one-off, or else I would have built a jig to cut the slats and one for the supports. Now I wish I had built the jig, because this thing would sell, and it is a great geometry lesson for more advanced students. We built the whole thing in two days, which is 5.5 hours each day for the students. We spent about an hour the day before that ripping all the slats. Keep in mind this was teaching and engineering as we built it, explaining how to figure out angles, and letting students take turns making cuts and assembling, so it goes slower than just building it.

    We are a non-profit that teaches trades to at-risk youth. Selling what we make is part of how we keep the shop going. They really did a fine job on this one. Any feedback will be passed on to them.

    www.mybrothersworkshop.org
    Attached Images Attached Images

  2. #2
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    I think the original was made by gluing the slat assemblies together as the first step, then those assemblies were attached to the vertical supports. With regard to the upper shelf, the spans are short so the glue and multiple slats bearing the weight of the flower pots was adequate for most small house plants.

  3. #3
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    Nicely done Malcolm! I would have done the same - over engineer it so somebody doesn’t put a big soaking wet plant right where there’s no support.

    And I didn’t know about your non-profit. Sounds very worthy - good on you!

  4. #4
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    Ya'll did good
    Ron

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    That's a rad non profit. Good work! Love seeing people helping their community.

    We have a non profit in Ogden (Youth Impact) that has a side goal of doing this as well. I was helping w/ a welding class before covid. They have some 'woodworking tools', but I am afraid to use them with the kids. What are your minimum age requirements? I believe OSHA requires 18 yr old or older, but the non profit in Ogden doesn't deal with teenagers older than 18..

  6. #6
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    Well done Malcolm - certainly for the plant stand, but more so for the work you do with those kids. You'll get bonus points for that I'm sure.
    You know, the worst ain't so bad when it finally happens.
    Not half as bad as you figure it'll be before it's happened.
    - Bob Curtin

  7. #7
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    Good job with the stand and the kids. It looks like it was originally designed to be made of wicker or popsickle sticks and making one in bigger sizes needed to include more bracing as you did.
    Bil lD

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    Humans like you make this world a better place!

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    Quote Originally Posted by andrew whicker View Post
    That's a rad non profit. Good work! Love seeing people helping their community.

    We have a non profit in Ogden (Youth Impact) that has a side goal of doing this as well. I was helping w/ a welding class before covid. They have some 'woodworking tools', but I am afraid to use them with the kids. What are your minimum age requirements? I believe OSHA requires 18 yr old or older, but the non profit in Ogden doesn't deal with teenagers older than 18..

    Minimum age is 18 and usually range up to 25 or so, but we do take older, and on Fridays I have some high school kids that come and we make simple stuff- no saw use for them. I precut their stuff or they watch me do it.

    Thanks all for the replies. I love what I am doing now.

  10. #10
    A noble effort by all involved. Well done.

    And thank you.

  11. #11
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    Very nice work, both with the product and the goals of the organization!

    One thing that struck me about the original pictures is the appearance of lightness (not so much the reality of the weight). While your version is definitely stout enough, and weighs little enough, it looks significantly heavier than the original. Some of that cannot be helped, due to the necessary additional structure to amend the original's deficiency.

    I might have gone with fewer and/or narrower cross slats, to widen the spaces between them, and preserve the appearance of lightness, as well as the actual mass.

    I like your solution for the top shelf, much better than the original.

    -- Andy - Arlington TX

  12. #12
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    You will find that working with that age group for a while you can go anywhere in your community and some kids will recognize you and say hello. It is interesting to see them grow up and hopefully use some of the life lessons you tried to teach them. My wife taught preschool and had a few of her students back in the classroom as parents.
    Bil lD

  13. #13
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    Quote Originally Posted by Andy D Jones View Post
    Very nice work, both with the product and the goals of the organization!

    One thing that struck me about the original pictures is the appearance of lightness (not so much the reality of the weight). While your version is definitely stout enough, and weighs little enough, it looks significantly heavier than the original. Some of that cannot be helped, due to the necessary additional structure to amend the original's deficiency.

    I might have gone with fewer and/or narrower cross slats, to widen the spaces between them, and preserve the appearance of lightness, as well as the actual mass.

    I like your solution for the top shelf, much better than the original.

    -- Andy - Arlington TX
    All things I also considered. I knew this one was going outdoors and would be used for some fairly heavy plants. I was worried it was going to be too heavy. Surprisingly, it could be lifted by one person, except it’s just cumbersome, so two people to actually carry it. Now here is the raw truth: I also wasn’t sure how well we would get these to land right on center, so I made the supports plenty wide! I also wanted plenty of meat around the screws. I actually would not change it now that I have seen how (to my surprise) light it came out. I went heavy and figured if we ever made another, maybe I would lighten it up, but now I think it is good as is.

  14. #14
    Great project that teaches thoughtful engineering in addition to woodworking. Do you teach design and business skills in classroom settings?

    I am impressed with your program and your great results. I donated.

  15. #15
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    That's a great looking plant stand, and also lovely to hear of your work with at-risk young people. It takes talent and effort to teach (haven't done it, don't think I could) so good on you.

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