r/myog • u/RADsupernova • 3d ago
Need some ideas. Planning something interesting (to me)
Okay, so I'm a big fan of upright steamer trunks (open like a book, not a chest). But anybody that knows anything about them knows they are heavy. I have been trying to come up with an idea to build one lightweight with cheap materials (like a pvc pipe frame) but the weight still stacks up fast. Something like that would need 50ft+ of pvc, and that's 12lbs and up. Make it 15lbs for the sake of actually getting it built right. Might not sound like a lot, but it compounds. A .5" plywood top and bottom adds somewhere in the ballpark of 10lbs. So were at 25lbs with only a frame and the rigid top and bottom panels. No cladding, no internal compartments. I still have room to go, but once I start getting above 50 and into 60-70lb territory, I'm into actual steamer trunk weights and have lost the plot on the whole idea. So I guess the question is... Can anyone suggest materials, methods, or anything that would help to make this sturdy yet light while still being cost effective and easily found?
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u/AccidentOk5240 3d ago
Can you just retrofit a large hardshell suitcase for your purpose?
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u/RADsupernova 3d ago
That might be an idea with the right suitcase. I could make it look more steamer like
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u/Western_Truck7948 3d ago
Aluminum would be my go to. PVC would flex a bunch and take up too much room (and still be heavy). I'd say 0.050 sheet, then some 0.125 trim should give it enough strength. I'd also use rivets, it would take a decently skilled welder to weld that thin.
Materials are easily sourced, but it's a whole different section of MYOG though. I would still put it on the easy side of fabrication, especially just the trunk itself before drawers and such.
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u/Dragongeek 3d ago
PVC as structure is a very wrong way of going about this. Not strong, heavy, etc.
The "best" way in this case if your goal is lightweight and strong is (unfortunately) composite work which tends towards expensive. Make some big foam molds for each half (or just one), ensure mold releasable, and then layup glass or carbon fiber with epoxy. Maybe add some CF tubes as "bones" for torsional stiffness.
The problem is that this needs a lot of space and can get expensive.
A cheaper variant is probably to build a frame out of aluminum L profile, welding TIG to join it, and then filling in the panels with sandwich board. Most lightweight (and expensive) would be foam-core fiberglass/carbon fiber boards, but depending on the expectated loads, you might be able to get away with plastic "cardboard" corrugated boards.
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u/killpony 20h ago
Two approaches - rigid frame or rigid panels. Plywood and PVC are just about two of the heaviest materials you could start with.
Aluminum or steel/stainless tubing (yes steel- higher strength = less material needed) will have good strength and stiffness in all directions and a solid amount of section to attach to - think tent-poles and other collapsible structures. For the panels coroplast is a good option -cheap, stiff, light, durable and straightforward to work with - it's what mail carrier boxes are made from.
If you want rigid panels your best options are composites - but you might be able to get away with plastic sheets with the right geometry. Fiberglass - containing glass - is dense by nature - but it has high stiffness so you can get away with thin walls. With any sheet/ panel based construction you can gain a lot of stiffness with the right geometry. Take a look at rigid suitcases and you should notice a lot of them have ribs or other convolutions in the surface - those features are key in lending stiffness to large flat panels. If you want to go a no-cost, recycled material route you might be able to cut sections out of old trash/recycling bins or other big plastic panels and then use a heat gun to slump them down (making sure you have ribs) and then cut your panel out.
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u/gemurrayx 3d ago
I would try to find something like this:
https://www.chairish.com/product/300744/vintage-fiberbilt-case-a-pair
I have one of these and it’s pretty lightweight. From what I can find they were used to hold equipment in the film industry, although this model is old enough that I can’t find out what this size was specifically used for. Mine is perhaps ten pounds empty, really tough, and is too large to even use as checked luggage at the airport. You’d have to figure out the best way to add wheels and whatever you’re mounting inside, but they come in a variety of sizes. The real challenge would be finding one that was the right fit for you and was in your price range.
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u/RADsupernova 19h ago
Okay, after hearing a bunch of your suggestions and doing some thinking of my own... What would everyone think of a rigid frame with a waterproofed canvas cover over it?
And should I leavethis here as a comment or add it as an edit to the post?
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u/Diligent_Honeydew295 3d ago
Fibre glass/spun basalt/carbon fibre in resin.
Skin and frame canoe kind of thing?