Growing cubic pumpkins/squashes/watermelons?

[TheWaterbug]

My kid is crazy about Minecraft, a virtual-world game where everything is drawn as simple cubes, including pumpkins.

I've seen"square" (actually cubic) watermelons in the news, so I thought I might try the same thing and grow a real Minecraft Pumpkin this year.

As it turns out, someone actually makes and sells an 8"watermelon cuber, but it's $110. Plus shipping.



I'm crazy, but not that crazy. So I'm thinking I should build my own cuber. Does anyone see any reasons why a pumpkin would be harder to force into a cube than a watermelon? Are they "stronger?"

I can buy cut-to-size sheets for a fraction the cost of the finished cuber linked above, and I'm thinking the hardware should be only a few bucks more. I need to use something clear, otherwise the pumpkin won't turn orange.

Should I use acrylic/Plexiglass or polycarbonate/Lexan? What thickness should I use? Does that ready-to-use cuber look like 1/4" thick?

Any other suggestions?

[DoubleDogFarm]

I think you should try this

https://www.neatorama.com/2008/10/29/hum ... d-pumpkin/

Apparently you can remove the mold and it will continue to grow and mature.


Eric

[DoubleDogFarm]

Build one out of hog panels. It may not only be square but segmented.

A imprint of "The Last Supper" and sell them on Ebay.

Eric

[ReptileAddiction]

I would use the polycarbonate because IMO the glass would just be to weak. I would also go at least 1/4 in. That is what the cuber looks like and I think anything smaller could be to weak if the pumpkin wants to get big. I would also make the box bigger than an 8 inch square. I think it would be much neater if it was like 1 foot by 1 foot. You would have to change that though based on the variety of pumpkin because a jack be little will not fill even an 8 inch square.

[TheWaterbug]

I've read in a few places that polycarbonate ages poorly in sunlight unless uv coated, and that it also has poorer scratch resistance. But that it's way stronger.

From that site I can get six pieces of 12" x 12" of either material in either 1/4" or 3/8" at a decent price.

Do you know if there's any material difference between extruded and cast acrylic?

Have you worked with both materials?

[applestar]

I have no advice, but I can't WAIT to see you get started and their progress.
WAY cool!

I wonder which will get more attention at the party -- the giant pumpkin or the cubic one
...you may have to carve a frown face on the loser. or ...

[ReptileAddiction]

I've read in a few places that polycarbonate ages poorly in sunlight unless uv coated, and that it also has poorer scratch resistance. But that it's way stronger.

From that site I can get six pieces of 12" x 12" of either material in either 1/4" or 3/8" at a decent price.

Do you know if there's any material difference between extruded and cast acrylic?

Have you worked with both materials?

I have worked with acrylic and glass not the poly. I did not know about the poly aging poorly. Do you have a place that can uv coat it for you?

[n8young]

This topic is absolutely awesome. Square watermelons would be soooo much fun. And...so much easier to eat.

[rainbowgardener]

This topic is absolutely awesome. Square watermelons would be soooo much fun. And...so much easier to eat.

I agree, very fun. But I don't understand. Square melons or pumpkins are obviously easier to stack and ship, maybe even to slice, since they don't roll around. Why would a square watermelon slice be any easier to eat than a round one? You have to cut it in half to get to the middle anyway.

What about other shapes?


https://www.whataboutwatermelon.com/wp-c ... -heart.jpg

I understand the molds would be a lot harder to build than boxes. But you could probably manage pyramids....

here's a giant one

https://www.wc-news.com/wp-content/wc-ne ... rmelon.jpg

then there's this:



apparently for some reason the japanese are big in to this stuff and the weird shaped watermelons sell for $100's. https://www.tofugu.com/2008/08/15/japane ... rd-shapes/ If you could figure out a mold material that is flexible enough and strong enough to do this you could make a lot of money, selling the melons. Could a pottery maker make an appropriate size and shape mold out of clay and fire it? Will the melon still ripen if it is inside a dark box? There's moldable plastic resins that come in clear.

[TheWaterbug]

I've read in a few places that polycarbonate ages poorly in sunlight unless uv coated, and that it also has poorer scratch resistance. But that it's way stronger.

From that site I can get six pieces of 12" x 12" of either material in either 1/4" or 3/8" at a decent price.

Do you know if there's any material difference between extruded and cast acrylic?

Have you worked with both materials?

I have worked with acrylic and glass not the poly. I did not know about the poly aging poorly. Do you have a place that can uv coat it for you?

That same site has abrasion-resistant, UV-coated polycarbonate, but the 1/4" UV-coated poly is quite a bit more than the 3/8" cast acrylic.

And then there's the cutting problem. I don't have access to a bandsaw or table saw. But I do have a brake at work. What's the thickest acrylic that you've successfully scored and snapped? What about snapping poly?

I don't really care too much about the quality of the finished edge as long as I get a square box, but I don't want to save money on material and then waste half it through my own incompetence/inexperience. As it is I will probably buy at least one spare piece to learn on.

Regarding the size, that's a tough question, too. I thought about using the 12" pieces as-is, and making a one cubic foot box, but then I tried converting that to an approximate weight. One cubic foot of water weighs 62 lbs. Guesstimates on the density of a pumpkin range from ~50% - 75% that of water, so a 1 cu ft pumpkin could weigh in the neighborhood of 31 - 47 lbs, which is a pretty big pumpkin.

On the other hand the 8" x 8" x 8" box is only 0.30 cu ft, which would be a ~9 - 14 lb. pumpkin, which seems a bit small.

10" x 10" x 10" would be in the 18 - 27 lb range, which seems about right, or perhaps slightly optimistic



Then again I guesstimated the volume of a medium-sized water melon in my kitchen and was surprised to see that it was only 0.30 cu ft. I guess that's not entirely surprising, since that's the size of that melon cuber, but the melon seems larger than that in real life.

I'm growing Howden, Jack-o-Lantern, and Big Max (among others). Big Max should certainly get to this size, and the Howden and JOLs might, if they're doing well.

Maybe I should just stick with the 1 ft panels, save myself the effort of cutting, and put a Big Max in there.

Decisions, decisions . . . .

p.s. that site will cut to any size I want, but sizes smaller than 12" are actually _more_ expensive than the 12" panels, I presume because they already have 12" pieces in stock.

[applestar]

Earlier in the summer, I was surfing the net for info on making cast concrete garden decorations -- birdbaths, classic and modern statuary, etc. There are quite a bit of DIY instructables, and plethora of mold suggestions, including the bit about pre-fab concrete mold rental. Some more stuff about ice molds for party table decorations.

These might lend themselves to pumpkin molding?

One idea that really had me thinking was using glass industrial lighting shades and breaking them after concrete had set to extract the finished product.

[TheWaterbug]

I'm thinking that pumpkins and melons would exert too much hydrostatic pressure for glass to handle, especially in the perpendicular direction. Glass is strong under compression, but weak in just about every other direction.

Materials like acrylic and polycarbonate are much more flexible and will "give" quite a bit before breaking, and even when they do they tend not to shatter.

I also want something reusable.

I think I need something transparent in order for the pumpkins to ripen properly (I think), so a wooden mold might not work well.

[ReptileAddiction]

I have no idea what the max width is for scoring and breaking. I would think you could easily do the 1/4 inch but the 3/8 might be pushing it.

[TheWaterbug]

I have no idea what the max width is for scoring and breaking. I would think you could easily do the 1/4 inch but the 3/8 might be pushing it.

Heh. The guy who wrote this comprehensive site on fabricating acrylic enclosures responded to my inquiry with "You would have to be superman to snap 3/8" acrylic."

Despite the opinions of my kid and my cat, my wife assures me that I am not superhuman.

I don't have a bandsaw or table saw, but I do have a circular saw and a blade with fine teeth. I might try sandwiching the material between two pieces of plywood when I cut.

I also have to think about the cutout for the stem.

Have you ever hand-sawn plexi with a hacksaw?

[DoubleDogFarm]

https://www.eplastics.com/Plastic/Plasti ... Plexiglass

Eric

[applestar]

Tossing ideas out -- do they melt or soften when heated?
- Red hot re-bar?
- Blowtorch then and use heat proof gloves/pliers to push/bend?

[DoubleDogFarm]

Tossing ideas out -- do they melt or soften when heated?
- Red hot re-bar?
- Blowtorch then and use heat proof gloves/pliers to push/bend?

oh stinky! Use a holesaw. Drill a hole and then make two saw cuts. Done.


Eric

[TheWaterbug]

There's a plastics vendor near work that sells scrap pieces by the pound, and they did the cuts for free, so I got 7 pieces of 10 x 10, 1/4" acrylic for $35, and didn't need to pay for shipping. I also got all the remnants left over after the cutting:

image.jpg (33.38 KiB) Viewed 2768 times

[sheeshshe]

what a fun project!

[TheWaterbug]

Use a holesaw. Drill a hole and then make two saw cuts. Done.

Done! I have a drill press at work.



Well, at least half done. I'll make the saw cuts at home tonight.

I'm off to Home Depot to find some brackets or hinges or channels or something to hold it all together.

[TheWaterbug]

My original plan was to build one exactly like this (except 10" per side), but then I thought if the pumpkin is really pressing hard against the fixed walls of the box, it might be impossible to slide it out, and it might require disassembling the box in the field to extract it.

Assume the sides are numbered like this:



I was considering adding a hinge at the 1-4 edge and a hasp at the 3-6 edge.

Another option would be to fix the 1-4-5 sides into one structure and the 2-3-6 sides into another structure with a hinge at the 2-4 edge and the stem slot on the 3 side, with hasps at the 3-5 edge, the 1-6 edge, and the 1-2 edge.

Any thoughts on this?

[DoubleDogFarm]

I would draw a picture but I don't have a scanner to upload.


I'm thinking a wood base. The bottom dosen't need to be clear. Cut 4 dados so the four side set in. Then cap with the plastic framed in wood with corresponding dados. Hold the whole thing together with a couple bungee cords.


Eric

[applestar]

You could draw a picture then take a picture of the picture with your camera.
Who needs scanners? It's all James Bond stuff, now,

[TheWaterbug]

So I finally built it today:





I did an absolutely _horrid_ job with the two saw cuts on the vine opening, but I don't think the vine will care. I also had to redrill for that one hasp that wouldn't close properly.

I have the mechanical repeatability of lightning (e.g. never the same place twice) so there was a lot of trial and error and fiddling, but I eventually got everything put together. Tomorrow I'm off to the garden to select a cube candidate.

Once it's all put together, it seems like it'll take quite a sizable pumpkin to fill it up. I'm thinking definitely one of my Big Maxes.

[ElizabethB]

I did not take the time to read every answer in detail or visit every link..In high school - oh so many years ago. I grew square melons by placing the young melon in a cinder block. As it matured it conformed to the shape of the cinder block and we had square watermelon. Of course a cinder block limits the mature size. You could just as easily make a box from scrap lumber.

The face molds are just too cool!

Can't wait to see pictures of your finished product.

[SOB]

Awesome...I'm so anxious to see how the melons turn out!

[Schnazleberry]

Hey awesome project! Love DIY stuff.
Great work but one think I would suggest if it's not too late is to add two more of those latches to the corners that have nothing because those un secured corners will bow out under pressure. How much is questionable, it may even be negligible, but it may not be.

If the door is #2 I'm talking about that corner on #6 and #1. They are opposite ends of the cube from each other.

Regardless, it's going to turn out awesome and I'm excited to see it! Inspired too.

[TheWaterbug]

If the door is #2 I'm talking about that corner on #6 and #1. They are opposite ends of the cube from each other.

Using the numbering from the red die photo above, you're talking about the 3-5-6 corner on the 6 face and the 1-2-4 corner on the 1 face, correct?

Yeah, those could bow out under pressure. It's not much effort to add pieces; I'll have to see if I have time to get to Home Depot this afternoon.

Of course now that I've been to HD 5-6 times and added a metric ton of hardware to my expensive acrylic pieces, my "savings" from not buying the manufactured product divided by my hours is far less than minimum wage!!!

Of course this way I get larger box. That product was only 8 x 8.

[TheWaterbug]

Hey awesome project! Love DIY stuff.
Great work but one think I would suggest if it's not too late is to add two more of those latches to the corners that have nothing because those un secured corners will bow out under pressure. How much is questionable, it may even be negligible, but it may not be.

If the door is #2 I'm talking about that corner on #6 and #1. They are opposite ends of the cube from each other.

Well, you were 100% correct. 2013's cubic pumpkin was an utter failure, along with nearly my entire pumpkin crop, because I planted too late. Most of my crop rotted, the rest of it never even set fruit, and the one in the cuber didn't even fill out 1/3 of the volume.

2014 was a failure in a different way. As you suggested might happen, those un-bound corners bowed out under some tremendous pressure. My weakest panel (from the cutout) just broke off:



Things were so distorted that it was impossible to release the hasps. I had to unscrew the hinges and three of the hasps before things sprang open. Here are the ruins of the cuber afterward:



and here's the pumpkin itself:



It's not a total failure, but it's not what I was hoping for, either. It has some geometry to it, but there's no "presentation angle" from which it looks like a real cube. Oh well; there's always next year. Tomorrow is the 5th annual pumpkin party.

I do have one extra plexiglass panel; I may replaced the broken one with a panel that has only a central hole drilled in it, and I'll put the pumpkin inside when it's very small, so I can just put it through the hole. I'll cut off the vine beyond the fruit, so that I won't have to worry as much about the vine.

And I'll reinforce those two extra corners, too.

[rainbowgardener]

well, it seems tricky. If the cube is bigger than the pumpkin, it won't make any difference and you will still have round pumpkin. But it seems like if the cube is very much smaller than the pumpkin wants to get, nothing will contain it.

[TXfarmer11]

Thanks for this thread. It was very informative.

I thought to build my own mold but a friend found these online for much less (time/money) than I could build an untested one for.

https://www.melonmold.com.

I'll update this as the growing occurs.

[TheWaterbug]

Thanks for this thread. It was very informative.

I thought to build my own mold but a friend found these online for much less (time/money) than I could build an untested one for.

https://www.melonmold.com.

I'll update this as the growing occurs.

I bought the cube one and the heart one. Here was the heart 10 days ago when I put the pumpkin in:



and here it was yesterday



Apparently I need to find a pumpkin whose destiny is _exactly_ the volume of the mold.

I put the cube mold around a fruit that aborted, so I just took it off and put it around another fruit. There's a lotta screws on these things!

If I can find it, I might try my old home-made mold as well.

This is much harder than it looks!

[rainbowgardener]

Yeah as I said on previous page, it seems very tricky. If the mold is more than slightly bigger than the finished melon size, it seems like the melon won't get shaped. If the mold is more than very slightly smaller than the finished melon size, it will get bowed (as in your previous page picture), cracked, etc. I expect the growing melon can exert a LOT of pressure.

It seems like what is needed is a mold with just a little bit of give/flex at the seams. Little enough that it still squeezes/shapes the melon, but enough to keep the mold from breaking. Tricky. Can the screws be loosened to make a little more room?

[TheWaterbug]

I could loosen the screws to make 1/8" more room, but I doubt that would matter much to the pumpkin. They want to be big!

But, from the link on the previous page, if I remove the mold the shape may persist through some additional growth.

So I'm going to pull the heart mold off this evening and put it on a new fruit. I'll wrap it with a nylon strap to hold it together, and when the new fruit fills it out to about 95%, I'll take it off again.

Maybe I'll get a few hearts out of this.

[applestar]

Looking forward to seeing progress reports/photos.