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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Thanks! The smallest version I have made is the blue 3-D printed example on the first page of this instructable. There's a video showing my son shooting it. I think it's somewhere around 9 or 10 inches tall. I have thought about making one out of a standard wooden pencil. At that size, pencil thick wood will probably be fine. I think the easiest thing to use for a small one would be square dowels. 1/4" to 3/8" inch thickness would probably be good. At that small size, I wouldn't try to make a sling pouch for the projectile. I would leave a string permanently attached to the projectile, with a loop on the other end of the string. The loop goes over the trebuchet finger, and the whole thing (projectile plus string) gets thrown. I made my tiny projectile out of hot glue.…

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    Thanks! The smallest version I have made is the blue 3-D printed example on the first page of this instructable. There's a video showing my son shooting it. I think it's somewhere around 9 or 10 inches tall. I have thought about making one out of a standard wooden pencil. At that size, pencil thick wood will probably be fine. I think the easiest thing to use for a small one would be square dowels. 1/4" to 3/8" inch thickness would probably be good. At that small size, I wouldn't try to make a sling pouch for the projectile. I would leave a string permanently attached to the projectile, with a loop on the other end of the string. The loop goes over the trebuchet finger, and the whole thing (projectile plus string) gets thrown. I made my tiny projectile out of hot glue. Good luck!

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  • mrstapleton commented on JoshXarles's instructable The Ski Sled MKII
    The Ski Sled MKII

    Nice! I've made several ski sleds, but never a two-ski version that I could control. I will definitely be taking a closer look at your steering mechanism when I get more time.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    I did Make an earlier version with a hinge, but it didn’t go as far.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Hi Peter,Coincidentally, the Make Magazine editor also wanted to know how I "evolved" the Walking Arm Trebuchet. It's explained in the new issue of Make (volume 71 https://www.makershed.com/products/make-magazine-volume-71-print). I would elaborate here, but I agreed to not share the information until March. I assume they will add the article to their website after the physical magazine has been out for a while.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Looks good! I have uploaded a couple of pictures of my release. The key element to the trigger is the washer with a section sliced out of it. It's the same basic principle as the one my son used on his little one, shown in step 17. I welded a steel rod to the washer so that the trigger would have a longer lever arm and would be easier to rotate and let the cable slip out. Instead of the ropes that my son used for guy lines, I used 1/8" cables.In my pictures, the pieces of sheet metal and bolts are the safety mechanism that I keep on the launcher until I'm ready to fire. It's for safety, but mostly it keeps things together while I get set up. To set the safety, I connect the guy wires to the trebuchet, via the trigger. Then I insert the two pieces of sheet metal so that each sl…

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    Looks good! I have uploaded a couple of pictures of my release. The key element to the trigger is the washer with a section sliced out of it. It's the same basic principle as the one my son used on his little one, shown in step 17. I welded a steel rod to the washer so that the trigger would have a longer lever arm and would be easier to rotate and let the cable slip out. Instead of the ropes that my son used for guy lines, I used 1/8" cables.In my pictures, the pieces of sheet metal and bolts are the safety mechanism that I keep on the launcher until I'm ready to fire. It's for safety, but mostly it keeps things together while I get set up. To set the safety, I connect the guy wires to the trebuchet, via the trigger. Then I insert the two pieces of sheet metal so that each slides partway into a notch on the trigger. If I have inserted the sheet metal pieces correctly, their holes will line up, and I can put bolts through to shackle the sheet metal in place (until firing). This keeps the trigger in place between the guy cables the the trebuchet.I drilled a hole in the trigger lever in order to attach a cord to pull and trigger the device. I usually place a stake behind the trebuchet and run the cord around that, so that I can launch from the side.When I'm ready to fire, I climb the ladder and remove the shackles.Here's a link to a time-lapse of the setup and loading process...Looking at your photos, I'm wondering if the distance from your axle to the counterweight is long enough. It looks like it might be shorter than mine, but it could also be the perspective.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Good luck! A few more things that might be helpful...If you're not trying to keep the whole thing as light as possible, you might want to make the triangle base leg (the one that hits the ground and serves as the triangle's pivot point) out of steel pipe. When everything goes right, the ripped 2x4 that I usually use is strong enough, but when something goes wrong, that section can twist and break. Most recently, the thing that went wrong was that I was using cables to stop the triangle's forward motion (as you can see in the "pumpkin chicken eve" video), and the stake that was holding the cables pulled loose, so the triangle didn't get stopped properly. One side of the triangle slid forward more than the other side, twisting and breaking the bottom of the triangle. I will u…

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    Good luck! A few more things that might be helpful...If you're not trying to keep the whole thing as light as possible, you might want to make the triangle base leg (the one that hits the ground and serves as the triangle's pivot point) out of steel pipe. When everything goes right, the ripped 2x4 that I usually use is strong enough, but when something goes wrong, that section can twist and break. Most recently, the thing that went wrong was that I was using cables to stop the triangle's forward motion (as you can see in the "pumpkin chicken eve" video), and the stake that was holding the cables pulled loose, so the triangle didn't get stopped properly. One side of the triangle slid forward more than the other side, twisting and breaking the bottom of the triangle. I will use some more serious stakes (1" steel pipe) next time, especially if the ground is soft.When I first built the big trebuchet the main arm pulled apart at the axle. That's why I have it so heavily reinforced with sheet metal.As I've dialed this trebuchet in, the g forces have apparently reached beyond what a pumpkin can handle. I am hoping that freezing the pumpkins will help. I'm also planning to freeze 5 pound water balloons and try those for projectiles. The trick will be supporting them so that they stay in a spherical shape as they freeze. They may also fracture.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Hi SaugenM,I am going to upload some photos and one diagram that I just sketched out. I never drew up a design, so I just went back and measured the one that I made. The wood is from Lowes -- as dry, straight, and clear-grained as I could find. The main arm was a 2x6x10. The rest is 2x4 that I either cut to length or ripped to half its normal width. I think all of my cables are 3/32". I went with steel cable because I didn't want to lose energy to stretching ropes, and also because my ropes and pouches were breaking. I have seen a few trebuchets that others have made, using my general design, and there are a couple of things I've noticed that I think have reduced their performance. The first is that there is a tendency to make the main arm too heavy. The heavier it is, the …

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    Hi SaugenM,I am going to upload some photos and one diagram that I just sketched out. I never drew up a design, so I just went back and measured the one that I made. The wood is from Lowes -- as dry, straight, and clear-grained as I could find. The main arm was a 2x6x10. The rest is 2x4 that I either cut to length or ripped to half its normal width. I think all of my cables are 3/32". I went with steel cable because I didn't want to lose energy to stretching ropes, and also because my ropes and pouches were breaking. I have seen a few trebuchets that others have made, using my general design, and there are a couple of things I've noticed that I think have reduced their performance. The first is that there is a tendency to make the main arm too heavy. The heavier it is, the more energy will be spent moving the arm, rather than the projectile. The design survives launches surprisingly well, even though it looks spindly. The second thing is that the axle can have a lot of play in it. As long as the counterweight is set up to fall and pass through the triangle, there can and should be a lot of slop in the axle. That way, if the fall of the counterweight is off by a little bit, there won't be a lot of friction and forces exerted by the tight axle. It will still be supported by the triangle.If you have more questions, let me know.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Hi SaugenM,I took some photos of it last night, but I didn't have a tape measure with me in the barn. I'll take some of the crucial measurements and try to get pictures, dimensions, materials, etc. to you tonight.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Hi g19fanatic,Here's the set-up video you requested... The VT Pumpkin Chuckin Festival is tomorrow, so I did a test throw. The ground is so soft at the venue that I have to put plywood down to support the trebuchet when it lands. I learned that lesson two years ago; it sank into the ground and broke itself. Sadly, it didn't look spectacular. It just broke the triangle and the weight thudded on the ground.Last year I used a couple of 2x6s to stop the triangle. This version uses some cables to stop the triangle's motion, so I don't have to guess where the 2x6s should go.My son, wife, and some relatives came to watch. This 5 pound soccer ball filled with rice went about 870'. Maybe farther. It rolled to 975'. Here's the launch...

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Thanks for the link! Regarding loading the big one, I take the weights off, stand up the trebuchet, and then put the weights back on, one-by-one. It sounds pretty labor intensive, and I guess it is, but compared to most of the other big trebuchets I've seen, it goes pretty smoothly. I've only had one scary moment. The first time I launched it, the stakes for my guy lines weren't long enough, and the trebuchet started to fall over as I was adding the 8th or 9th 45 pound weight. As I recall, I dropped the weights and jumped off my ladder, and the trebuchet fell semi-gracefully to one side.Right now it's up in my barn loft, but I will be getting it out again for pumpkin chucking one week from next Sunday. I'll get some video of the loading process then. I've thought about rigging up a…

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    Thanks for the link! Regarding loading the big one, I take the weights off, stand up the trebuchet, and then put the weights back on, one-by-one. It sounds pretty labor intensive, and I guess it is, but compared to most of the other big trebuchets I've seen, it goes pretty smoothly. I've only had one scary moment. The first time I launched it, the stakes for my guy lines weren't long enough, and the trebuchet started to fall over as I was adding the 8th or 9th 45 pound weight. As I recall, I dropped the weights and jumped off my ladder, and the trebuchet fell semi-gracefully to one side.Right now it's up in my barn loft, but I will be getting it out again for pumpkin chucking one week from next Sunday. I'll get some video of the loading process then. I've thought about rigging up a winch to lift it up with the weights still on it, but it hasn't been worth the trouble.I haven't put much effort into trying to hit targets with it. I'm a science teacher, so I'm a little ashamed that I really haven't done much controlled scientific testing. I'm just not that self disciplined when I'm out shooting trebuchets. So while I may have some good ideas here, I may end up being only about 51% correct. That said, to get a lower trajectory I would first adjust the tuning string. In general the trebuchet shoots lower when the triangle is lower. You could also add an adjustable finger to delay or speed up the release. I think a shorter sling should also cause the projectile to swing around faster and therefore throw lower. Up to a point, I think adding weights should both increase projectile speed and lower the launch angle. I will say that when we tried throwing water balloons with it, we actually had a hard time hitting the house (and not throwing over it). That doesn't bode well for this being a precision instrument of destruction, but those water balloons are squishy and wiggly, and maybe that was our problem. Plus, the house was uphill.If I wanted to attack something tomorrow, I think I would start by making about a 6 foot trebuchet with 50+ pounds of counterweight, and I would throw projectiles the size of an apple. That would be pretty easy for me to manage manually and to aim at a variety of targets.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    You're welcome!

    My first 3-D printed version worked pretty well. I just added a video to the first step, but here's the link. I was excited to try it out, so instead of bothering with a tiny sling pouch, I attached a permanent loop of fishing line to the hot glue projectile (painted black). The fishing line loop goes around the finger, and the whole thing (loop plus projectile) gets thrown together. As I expected, getting traction for the triangle wasn't easy. The triangle spikes are paper clips that I sharpened. If I had sharpened them some more, I might not have needed the paper towel.

    My son definitely enjoyed it. Thank you!

    It works better on the carpet. In the video with the mouse pad and paper towel, you can see that the whole mouse pad shifts forward. Here it is on the carpet...https://www.youtube.com/watch?v=L3yJ05MxOCE&feature=youtu.be

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    • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)
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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    Great! I’m a teacher, too. My engineering class is in the midst of their own trebuchet design project.

    Thank you! I would expect scaling down to work fine. I've been thinking of making a desktop version. Aside from the issue of the miniature sling and pouch, the trickiest part (I think) is going to be getting the triangle to dig in and not slide forward. The most simplest solution I can think of is to launch it on a mouse pad, and have little paper clip spikes that dig into the mouse pad. I just sent a quick model to the 3-D printer. I'll let you know if it works.

    Thank you! A lot of the credit goes to Dave Jordan, the guy who started the VT Pumpkin Chuckin’ Festival. Each competitive division has a total weight limit for the trebuchet plus it’s counterweight, so there is a strong incentive to build light and seek simplicity. It’s a fun problem.

    Great idea! Thanks!

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    We tried some water balloons today. The g's did destroy them. They sprayed all over before the pouch released. Then we tried some 12" balloons, but we kept them the size of regular water balloons. They survived the launch, and they broke when we hit the side of the house with them. Our yard slopes up toward the house, and we had a surprisingly hard time not throwing over it. Most of the balloons that went over the house survived the impact in the yard on the other side. I uploaded a video, but I'm not sure if it will work, since I used the "add images" button. If it doesn't work, I can use a YouTube link. The hail storm of balloons concept would take some work. I think you could do it with a large trebuchet and a bunch of tough balloons of the non-water balloon v…

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    We tried some water balloons today. The g's did destroy them. They sprayed all over before the pouch released. Then we tried some 12" balloons, but we kept them the size of regular water balloons. They survived the launch, and they broke when we hit the side of the house with them. Our yard slopes up toward the house, and we had a surprisingly hard time not throwing over it. Most of the balloons that went over the house survived the impact in the yard on the other side. I uploaded a video, but I'm not sure if it will work, since I used the "add images" button. If it doesn't work, I can use a YouTube link. The hail storm of balloons concept would take some work. I think you could do it with a large trebuchet and a bunch of tough balloons of the non-water balloon variety.

    Thank you for the nice feedback! We're glad you're enjoying the instructable.

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  • World's Simplest and Newest Trebuchet (Walking Arm Trebuchet)

    That's a good question about water balloons. I suppose it depends on how tough the balloons are. I'll ask my son if he has some that we can try.

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