floating arm trebuchet ratios

The axle will have to easily pass in between them. it would be much appreciated!! The two previous segments are diagonal supports. This will be the finger end of the arm. 3. This will prevent the counterweights from falling. 10 years ago yes, it works Give it more of a flicking action than a long drawn out flinging. denim fabric Approx 25 ft. (7.62 m)1/2 braided nylon rope then divide your total beam length by that number. 6 1/4 in. we didn't use a simulator for the motion. slide the bolt the rest of the way through the other hole. This list of materials is copied directly from my science fair project. i was hoping you could tell me what the release system was rated for and if you have any recommendations on where i can acquire a quick release, 8 years ago If you need more help with the guide blocks let me know. 11 years ago Make sure the washers do not interfere with the drop channel. 6. A traditional trebuchet, which is simple to engineer, consists of an arm resting off-centre on an axle with a hinged counterweight at the short end of the arm. 2 segments of 6 ft. (1.8288 m) long 1 X 6 Beside the arm when it's at rest, these two channels are the tallest point of the trebuchet. Ensure that the shafts you choose have a diameter that mates well with your inside wheel diameter, as well as your inserts. 6 1/4 in. WebThe optimal ratio between the long part of the arm and the short part of the arm will depend mainly on the Mass of Weight. *look at the last step: improvements. No specimens or models from medieval times survive. Do the same with the bottom of the board, the part that you held against the bending brace. The second length of rope is tied to a small ring- like a loose keychain ring. First, the two pieces are drilled and doweled. Funky Snicket Catapult. Use a washer wherever metal is coming in contact with wood. Documentation. To launch such a heavy projectile will require much more weight than the approx. 18. 1. Friction when the counterweight is dropping down to the glide strike can be reduced by using silicone grease or a thin film of plastic on the drop channel. To get it in, you need some sort of head on it for the wrench. I don't really know what I'm talking about. i need to make mine 3x3x3. The Cardan gear was invented to accept linear motion from a steam piston to create circular motion. Hopefully you'll use a wider bolt to begin with For the arm assembly Use your head before you lose your head. We are building one now, it has been lots of fun for the family. 2 1/2 X 10 eye bolts 24 5/8 in. WebFloating Arm Trebuchet - Hobbyist Version The F.A.T. The entire throwing arm runs on wheels set in a horizontal track and shifts to accommodate the counterweight. A solid metal ring of any kind would work better. If you wanted to simply use a board, it might be good to attach two long pieces of wood to the length of the board. It has two ropes coming off it, one in either direction. That should be about 2 inches from the end of the track. so then the long arm would be 3.5 times that on Introduction. We'd have done much better with something like this. I used a projectile motion program I wrote using Matlab last year, and assumed a release angle of 45 and initial height of 15 ft. (remember the CW is supported by the trigger at the beginning, and the the trigger is screwed directly into the drop channels. ) ), Reply The floating arm trebuchet is a counterweight siege weapon which is a modern variation[1] of the medieval trebuchet. The axle bolt hole would be drilled in the short arm 1.5 feet from the end. Next, going to the back of the frame, we have the guide wheel and the guide blocks. Additionally, I would make the arm as long as possible as well. 2 segments of 2 ft (0.6096 m) 1 X 6 What did you finally use for the rollers? I'd guess that for throwing oranges, you'd want to be around 5-6 ft high and an 8ft arm, and maybe 50-100 lbs of weight? The arm is split into two parts by the fulcrum. 7 years ago That is to say, you should make sure your drop towers reach the full length of the 80 meter height. The walking arm trebuchet is a good example, which uses an unconventional design to great effect. (while you're there, pull some harmonic balancers from a Chevy 350 engine for your wheels) Toyota or Nissan models work well for the trigger, and ours held with around 1000 lbs of tension on it.IMPORTANT: You should have a separate safety mechanism on your design. The second picture shows what it should look like after they are screwed in. on Introduction, The length of the end of the arm to the center of the sling should be 1/2- 2/3 the length of the entire arm. Your arm should look nice and smooth like the pics. What I do not It was an old rusty double- headed nail. Tighten the bolts together, sandwiching the washer. Our starter model was 1/6 scale, it threw a bouncy ball 270 feet with 10 pounds of counterweight. Remember, even if you drop the CW, the safety blocks will prevent the arm from swinging up. The pictures show two different models. 42. (15.24 cm.) Keep the top part aligned, and carefully trace a line on the diagonal along the edge of the base. Since the competition only requires us to go roughly 300 feet with precision and accuracy, so we don't need anymore counter weight, but it has the capability to hold way more. WebThere are no really detailed descriptions of medieval or earlier trebuchets that give, for example, the dimensions or shape of the beam, the ratio of its long arm to its short arm, and so on. Add the two numbers of your ratio together. That model was equipped with a folding gantry and pulley system to raise the counterweight, with that it could be fired every 2 minutes. This ring will be what loops around the pin. [3] If you It should be drilled all the way through the flatter 3.5 inch edge side. Remember the length really is only 1 ft 5 in. *(One note, this rod is probably too thin. Now, I believe that the width between the bottom of the main track supports is somewhere around 1 ft, 1 inch. Did you make this project? The key ratio of an arm is anywere between 3:1 and 5:1. This tape will further reinforce the areas where the string will go through. Cut these two twisting braces at around 1 ft 2 inches because the length of these will affect the width between the tops of the two drop channels. For the trigger you will need the: You will need the two 2- foot lengths of 1 X 6 and the two 6- foot lengths of the 1 X 6. The classic beam ratio for a FAT is 2:1. You also will need to push them out slightly, so that the gap is 3/4" at least. 6. Share it with us! 1/4" at the very most. Clamp the beam and let it dry, allowing the appropriate time for curing (follow resin instructions). You also want to keep the track in a straight line, otherwise the wheels will fall off the edge. (0.635 cm) bolts, matching thread The arm is done. 4. Lastly, make sure everything is square. If the weight is very heavy, the long part of the arm can Buy 15 2 X 4s to start off with, then buy more later. This, in turn, changes the width of the drop channels to narrow (BAD) or widen (usually better). Have fun and be safe. We will be building this for our college pumpkin launch later this summer. So now we're going to add some extra supports that will prevent the 2 ft 1 X 6 from bending, Lateral support and extra track support. For the diagonals you will need the I have real pictures, but no sketchup ones. It's a little bit tricky to get the angles perfect. The angle and length of the pin control when the sling opens. The wheel axle on the arm was tack welded in place, so that the axle remains stationary with respect to the arm, and only the wheels spin. I haven't seen much information on dynamic tuning for the f2k, but we did an estimate of the static loads at the critical points and kept the stresses around 1/4 of the yield strength of the steel.I'd also advise implementing a metal sheet on the rails, instead of bare wood. 9 years ago WebAn important part of whipper performance is the beam ratio, the ratio of long arm to short arm. Unless one eye bolt cannot support the weight, relax. Feel free to use them for educational or personal use. Without one of them , the arm would simply fall into the ground. erm And it is constructed with 1 X 6s Our team devised a problem statement: Design and construct a launching device to maximize the horizontal Leave a comment!!! long carriage bolts It's 6 feet long and 2 feet wide. Then just screw the bolt through when you need to. Slip the ring over the pin, and stretch the sling lines to get rid of as much slack as possible. (0.635 cm) diameter, 6 in. That was bad. (I had no idea what else to finish it off with. cut about 6 inches from the edge, along the 7 ft. arm. Again, the exact size of the support does not matter, but the long edge should be under 1 ft, 6 in. Use a wrench or hopefully a driver of some sort to drive the CW bolt all the way throughone drop channel, through the arm and out the other drop channel. I've definitely seen some trebuchets in that size range throwing tennis balls, 6" steel shot, etc very far. First, obviously, just lay the arm in between the drop channels (Just the middle of the treb) So if I could toss the weight a 100yds would be perfect. Reply So we built a 10 throwing arm trebuchet. The cutouts go around the main track supports. Unfortunately, there were some problems in the sketchup base that I made (and could not be easily corrected) that threw off a couple of measurements. 8 segments of 3 ft., 6 in (1.0668 m) long 2 X 4 Not a big deal, but if you want them to be the same height as the ones here, then you need to change the angle of the diagonals. Lastly, Alternatively, you can attach a heavy weight such as a 20 pounds (9.1 kg) hand weight directly to the end of the arm. You only want enough of the bolt so that after it comes out of the arm there is only enough room on either side of the bolt for a 3 washers, 2 bolts and the entire wheel assembly. (0.2413 X 0.2286m) 6 1/4 in. Again, this is not a critical dimension, something near that would work. The medieval trebuchet is a missile-throwing device, with a heavy counterweight on the short end of a beam that pivots about an axle fixed to a supporting frame. 1. This list of materials is copied directly from my science fair project. It includes what I used at the time. The lumber list is really long, but (0.7112 m) long 2 X 4 Simulator. Thanks for the great instructable! It is later screwed through the base and through the main track supports. I'd look around on YouTube and compare different sizes of trebuchets. Here, we followed the dimensions on the drawing and cut very precisely. The chain link on the opposite end should click into the door release easily. WebSmall floating arm trebuchet plans. 4 years ago. NOTE: all CAD modeling was done using student software, for educational purposes. Otherwise, The arm will get puched over and on top of them, slowing down the arm a lot. at this point, we used a ratchet to tighten the eye bolt, until the chain was in tension and the weight bar no longer made contact with the safety bars. 3. Place the weights in the box and screw on the top. None seem to affect it structurally, but we'll see. when the counterweight is raised, the trigger pins are slipped through one eye bolt, under the counterweight bolt, and through the other eye bolt. so: Make sure everyone knows you are firing. [2] The difference in the lengths of the two ends of the arm provides mechanical advantage. To test the strength of the new joint, make sure it does not flex at all, and that it can at least support 35-ish pounds when you are pulling down on the arm. Make them small as possible, but make sure they can still guide the arm until its wheels hit the track. Summary The floating-arm trebuchet, a modern variation of a medieval weapon, is a popular project for physics and engineering instructors.We develop and analyze a model of this device as an introduction to constrained Lagrangian dynamics. This was done with the safety bars in place, as well as the chain clicked into the trigger. 4. Approx 25 ft. (7.62 m)1/2 braided nylon rope The hardest part, really, is getting the angles correct and then cutting them accurately. Lastly, drill a hole through both the walls of each box at least two inches from the top edge for the counterweight bolt. It is scaled using the data of skullmech;s trebuchet, but taller as we had no hieght restriction. FDM 3D Printing; SLA 3D Printing; Their defining feature is free movement of an axle on the throwing arm,[2] and a linear drop channel for the counterweight. Drill the holes for the eye bolts. I don't remember the exact dimensions, but I think it was a little bit taller than 8 feet, and about 6 feet long. If the weights are extremely heavy, though, you may want to keep the weights out of the box for now, since when you load it you will have to lift it. The third clip in the video shows this problem well- the arm kind of rolled over and on top of the guide blocks because they were too high. The idea of inserting a trebuchet into the dynamics Just make sure you build the trebuchet on an even surface if you are using 1 X 6s, otherwise you will cut the main track supports shorter in the middle, causing the drop channel to be permanently narrowed. This one is pretty bad. Webi'm working on a quick sketch for a floating arm trebuchet i'm making in an engineering class and need help selecting and using the correct mate tool in the on shape assembly tool. Look at the second clip of the video for the safety "demonstration" (We accidentally left it in) coping saw and orbital sander (The one I used here) The frame is made of 4x4 held together with deck screws and carriage bolts, and our design allowed for the frame to be removed from the base with bolts only. I've uploaded PDF's of the CAD drawings as well as a general schematic diagram for an f2k. wood screws, phillips head drive, #8 Then just hammer the dowels all the way into the holes. We built a trebuchet that we call the medieval stuff chucker (MSC). 2 rectangles of 3/4" in. I only barely can, with only about 60 lbs. 5. Tbh I'm not sure exactly how well the trebuchet would work when scaled down , but I imagine that it should be fairly similar in terms of arm length and drop height etc. They are basically the same things as the 2 x 6 diagonals except they are 2 X 4 and they have more half-laps cut in them. Bending Braces. If you make the channel a lot wider, I would suggest using a wider piece of wood or strength. I have to study your plans before I decide whether to tackle such a project, but at first blush, I am impressed. Actual distance: 300 feet. 4 rectangles of 3/4 inch (1.905 cm) thick wood 9.5 X 9 in. Then fold in on top of the other one to crinkle the pouch into a more pouchy shape. Flexing will be reduced and you will have a stronger base to work with. Use the top bolt for screwing in, and the bottom one for unscrewing. This may change depending on the width of your wheels. 24. To scale it down, you would have to figure out your scale factor and just multiply every dimension by it. 4. So now we're going to add some extra supports that will prevent the 2 ft 1 X 6 from bending, Lateral support and extra track support. 1. Bending Does it take a small army to transport it? on Introduction. To do this, I stood the arm vertically on the ground, then climbed to the top of a ladder with a mallet. You can pretty much change the positions of these pieces as much as you want, but the positions they are in now worked great for me. um 9. 3 segments of 3 ft (0.9144 m) long 2 X 6 The two bits at the open top of the cut channel..keeps the drop channel from "opening" Now, let's get started actually building and attaching them. Long sides of the base on Introduction. GoochesVFD said that there was some cracking around the base of the long 2 X 4 used as the drop channel. The frame is made from 12mm diameter square cross section pine (I used a about 2.4m). Make matching steel plates and drill holes into them for bolts and for both the counterweight bar and the axle, allowing room for steel pipe inserts. Awesome trebuchet! This will stop fraying and make it more solid. how long was the arm after the extension? I have no idea if this is the most ideal design for this type of trebuchet. It's been 4 years since I built this in 8th grade (graduated high school by now), but its still lots of fun to set up and launch! again for the threaded rod I really appreciate your work in building this instructable. So, This project is not due until sometime in may, but I will be glad to post pictures. This way, it's easy to angle the board to get angled shots. This may need to be changed If not look at step 10. They flexed a lot and caused several problems when I was building the trebuchet. 7. Arm-sling constraint, arm roller on fixed track, projectile on ramp. First, I'm going to talk about some other improvements that are more important than the arm. Use a wrench to thread the threaded rod through the holes you made..make sure it fits and is level. (Hopefully a strong someone) The person standing on the trebcuhet is no longer in danger unless he drops the bolt on his foot. The arm wasn't too hard to extend, BUT whatever you use to join the parts MUST be strong enough. They are fairly simple to make. This is the pin. Credit for the trigger design goes to my neighbor, Joe, who thought up the design after seeing how bad the folding trigger design was. Mark the height that you want the diagonal support to rise to. trebuchet main track supports and track.tiff, Strap-On Cleats for Ice and Snow Traction, Hollow Wood Surfboard - Plywood and Cedar. -The box needs to be made narrow enough to fit on the outside of the drop channel and still have room to be loose..that's room for other bolts and washers. drip some wood glue into the holes, and put glue all over the dowels. The trigger pins keep the weight from falling. There should be two layers at the outside and 1 layer inside, in the middle. but if you didn't (my bad) You need to recut the drop gap to 1/8" wider than the CW bar, cut the gap in the track slightly wider, and spread apart the track supports directly underneath the drop gap. For me, for the side with the longer support, this was about 5 ft, 7 inches from the very bottom of the drop channel. [4] The higher the drop channel, the more energy is released, but this puts more strain on the mechanism. On the end of the arm, there will also be a nail, or some sort of strong metal pin. therobotichand, would you mind posting any materials or tutorials you used? If the shot releases at the wrong time, adjust the pin angle. It includes what I used at the time. This might change depending on your weights setup. -Make sure it is strong enough to take the force of your falling counterweight. For a traditional trebuchet, the optimum weight ratio is 133:1. A shorter length sling will work better for lighter projectiles, while a longer length will be better for heavier projectiles. on Step 15, This is stellar. The pinis crap. thick wood, 2 ft., 5 in. Forming tube is expensive, so instead, cut a cardboard barrel into strips or tack thick cardboard onto a piece of plywood to make forms. be safe Using the dimensioned drawings, estimate the amount of materials needed. Take a break. (Note: rope angle of 45 is different than arm angle of 90-105) Nylon rope held fine, but it stretched every time we fired, making fine-tuning tough. We built a 1/3 scale model that throws a 1 pound projectiles 340 feet + with 70 pounds of counterweight. -Use screws! Avoid contact with the arm as much as possible, they are only there to guide. 1. For this step you will need four of the eight 3.5 ft pieces, and the two 6 ft. long pieces. Well, they didn't becasue I did not have a drill press. 2. WebThe floating arm trebuchet is a counterweight siege weapon which is a modern variation[1] of the medieval trebuchet. on Introduction, hey I'm a physics student trying to replicate your design. After the first 25 shots or so with the trebuchet, there were two things apparent: the arm could easily be made longer and could greatly increase the range, and the the CW bolt needed to be made stronger. otherwise the long arm will be too heavy. (0.3175 m) long 2 X 4 For them to fit, I had to cut different lengths off of the diagonal supports. Make sure there is glue all over them. Simulated distance: 316.6 feet. [5] Friction of the wheel on the arm axle against the glide track should be managed in a similar way. Can the trebuchet launch a 6-lb shot? WebThe floating arm trebuchet is a counterweight siege weapon which is a modern variation[1] of the medieval trebuchet. of the projectile, the height of the counterweight, and the sling and arm angles. (Look at the picture) they would be horizontal, not angled. I simply layed a fairly long board over the diagonal supports in the back, extending out a bit to give support to the sling until it was lifted up into the air. 8 matching cut washers (if you do it, let me know; I'll tell you how to make fireball projectiles), 7 years ago You can use a clamp and a tape measure in combination to figure out the right lengths before you cut them. The thicker the better to prevent it from bending. for the threaded rod these are the trigger pins These go in the front. Then, drive in the screws. And lastly, for the extra supports, we have the lateral diagonal supports. Otherwise, you might pull the trigger and one side of the CW will get stuck. Grab 3 of the 2.5 foot pieces. Floating arm trebuchet (dimes and pennies) Desktop Trebuchet. -----------(pouch)----------- One end is tied through a hole that's drilled in the end of the arm. It will differentiate depending on your ratio. 2 hand weights, 8 lbs (3.63 kilos)* Simply miter off each edge at a 45 degree angle, so that the piece is the shape of a trapezoid. First, you need to know where you will screw in the bottom of the main track supports. If you need to beef things up, like the counterweight bolt and wheels, it might cost more. Short sides of the base Large scale designs require special trigger mechanisms that can hold the weight of the throwing arm. It wasn't the best design for very straight shots, but for me it worked very well. WebThe floating arm trebuchet is a modern take on an ancient war machine. Use a bowline. You may want to keep the weights out while you are doing this. (Safety blocks explained later) Consider how much weight you want to use, and size your shafts and frame accordingly. Otherwise, the washers in between the CW box and the channel will be smooshed up against the drop channel, creating friction, which is bad. 20 yell heads up, countdown , just make sure everyone know you are firing. Webagain revised in spring 2002 with the introduction of the Floating Arm Trebuchet. Unless I've forgotten something, I think we're done. MATERIALS LIST: -Lumber (4x4, 2x4, plywood) -Deck Screws (lots of them) -Carriage bolts, nuts, washers -all thread, 1/2", 1ft sections (for sling pins) -Harmonic Balancers ~7" dia (4X) -Steel Shafts, various diameters -Steel pipe, appropriate mating diameters to shafts -Bolts for bushings -Concrete (450+ lbs) and circular forms (OR just use gym weights) -Steel plates -Steel chain, 1900lb test, 3-4ft -Door latch mechanism from a car -Nylon rope (or other strong rope/cable) -Nylon webbing for sling -Axle grease -Welding equipment -Grinder -Drill press -Carpentry tools -Paint (optional). Now you simply lay the 6 ft pieces across the supports, lining up the edges, and drive three of the 2.5 inch screws into through the track and into the supports. The trigger will be added later. I recommend using a pin, then a thick nail, then a screw and finally a pencil to widen the hole for the string. then, to check we add the short arm and long arm length together: Check the alignment of the rails and ensure they are relatively close. if you buy pt lumber make sure they are approved for use in it.. Try to make it as flat and planar as possible, as this will minimize the need for adjustments later. User Projects. 11. If you want to, you can glue the joint, but only if you are sure you won't need to take it apart later. These are the four sections of 1 ft, 5 in 2 X 6. 5 years ago. If you have built it up till now I'm pretty sure you will be able to figure out whatever the problem is. Yes I want a small one for the classroom and large one for the field. WebThe Cardan Gear Linear Motion Trebuchet is an adaptation of the motion found in a Cardan Gear adapted to a straight track-drop trebuchet. Now comes the fun part. Then drive 2 screws through the board with the actual channel on either side of the gap, diagonal from each other so that you can fit two into the narrow width of the wood on either side of the gap. So, cut the first twisting brace, on the very front, as wide or narrow as you need it to keep the drop channels straight. The trigger held up well, but it did take a pretty hard tug to get it to release with max weight. So for a 3.5:1 ratio and 7 ft beam, my short arm would be 1.55 feet and my long arm would be 5.6 feet, more or less. Also, get the most straight lumber available for the longer pieces on the frame. DRILL PILOT HOLES FOR EVERYTHING!!!!!! After going through much analytical geometry, etc., etc., This thing is powerful, which is why you need a trigger. They would extend outward, just like the board chute. Then, measure 3/8" from either side of this mark. 16. The weight bar was 1.5" diameter, AISI 4140 cold drawn (probably overkill) and the axles were 1.2" diameter, AISI 1020 CD. Put the ratio hole wherever it goes. The picture shows just 4 pounds of counterwieght, we added up to 10 pounds for maximum throws. 2. 15 in. Tie the longer end of the rope through the hole in the end of the arm. (1.5875 cm.) If anyone takes the time to do a thorough dynamic analysis on an F2K trebuchet, and would like to share their results, please post them below. This will be the top. Or you could use the angles I give you. 6. Their defining feature is free movement of an axle on the throwing arm, and a linear drop channel for the counterweight. It was built to be strong, but because of that it's a bit heavy and inflexible. thank you, Reply 7 years ago. Now I'll tell you how to lock load and FIRE! You should also cut off the head if you keep getting downward throws no matter how you adjust it. (Flanges would work here as an alternative) We added a tapered cut to the arm, going from 4x8 to 4x4 at the tip.

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