If you rotated the wheels by 90 degrees so they remain flush against the body, you might be able to make a really powerful bow that meaures incredibly thin on width. I imagine this would make it more mobile and easier to carry, especially around corners and low arches. I know folding limbs exist on a crossbow, and crossbows are meant for hunting so you'll typically be out in the woods and not in either of those 2 situations very often, but the idea of a long and skinny crossbow seems pretty novel to me.
That's what I was thinking too and I think I'll try to do it this way, I will also probably make it longer so there's more guidance for the bolt and more space for the springs
good design. i would recommend putting safety wires through the springs though. that way if the springs break they don't go flying everywhere and hit you in the face. i used to work on garage doors and that was a problem with some of the older systems that home owners would install. its a good idea for anything that uses extension springs
My thought was to have the springs inside of tubing attached to the stock so the spring is inside and cablesruninto end and attach to the spring . So if the cables ever break you want get those springs in yer face
@@aurigo_tech I also just realised you could potentially increase the drawweight by adding torsion springs around the shafts that transmit the power from the lower wheels to the upper ones. It would shift the cg forward though.
One advantage of springs is that you that you really can extend your draw length and weight and also put them in Series or Parallel. So maybe having 4 springs that are lighter but have a longer draw length might be better. Maybe. Idk. It is a very impressive design. Really awesome design. You could probably turn into a slingshot too.
Series will reduce draw weight but will increase the draw length, allowing a lower cam ratio. Parallel will increase draw weight while maintaining the same draw length. If the man is gonna add the weight of two more springs to his design, I think he should go with the parallel option since his 4.5 to 1 ratio already works fine.
Hello, I tried to modify your construction a little by not using round pulleys on the string, but in the shape of a three-quarter ellipse with a ramp from a smaller to a larger diameter, it made stretching the string a lot easier, since the largest diameter of the pulley is actually at the point when the spring is "free" " is basically in zero action and as we pull the string further, the diameter decreases and the closer we get to the maximum tension of the coil spring, the diameter of the pulley for the string decreases and thus we develop less force for stretching, but at the same time it simplifies the start of the string, the greatest force it is actually on the smallest diameter of the pulley and as the diameter increases the power decreases, but the speed of the string increases and so does the arrow, I use one spring not two, and it is built into the duralumin body of the crossbow, actually it is not one, but two, they are pushed in itself, it is softer on the inside and harder on the outside, in addition, they are longer and for better balance the end of the springs is attached to the pin before the end of the stock, while the trigger mechanism is designed around the driving coil springs, I charge with a lever that pulls the string up to above the spring and is integrated in the crossbow frame, I also have an industrially produced hunting crossbow with a reverse reed and elliptical pulleys, I must state that the home-made spring crossbow has significantly more power, I don't know exactly how much, but the arrow shoots at a speed of 508 m/s, it is absolutely accurate at 30 meters, after 40 meters already the ballistic curve works and the arrow goes down, but the arrow hits the oak tree 2 cm deep at 70 m, which I think is a respectable force, at 10 m it pierces a 5 cm thick spruce board and the arrow simply goes through the whole thing and flies even further, at 20 m it goes through straw I aim for a third of the length. I'm currently dealing with loading from a suspended arrow magazine, I'm mainly interested in ensuring that the mechanics fit the arrow accurately into the arrow holder and always in the same way, both deep and sideways, and the accuracy of shooting depends on that, there are still malfunctions, but it's already going well in 90 percent of cases, you can put it on the same way, but it is only about the correct clearance in the arrow feeder and the pressure of the holder, the repetition speed is about 6 seconds, which I think is good for a crossbow. Thanks for the inspiration, I would never have started this even though I know the principle of course if I hadn't seen it from you. good luck :D
Well, sounds like you put in a lot of work and thoughs on improvement of the general idea. Are there pictures or video of your design anywhere? In any case nice to hear from someone picking up the idea as well. I am thinking about non-circular cams as well of course, as already stated in the video. But I had some other things going on in life which is why not much happened in this topic. However for now I am working on implementing the idea in a bow - that should come out sometime this year.
I don't know if you are aware, but what you've built is basically a crossbow version of a type of speargun called a "roller gun". They are by no means a new invention, I think the first one came around in the '60s but for some reason, they disappeared until maybe 10 years ago or so, and by far most of the ones I saw back in the days before I started building my own, were homemade guns. These days they are manufactured by a couple of companies I think, or you can get drop-in kits to modify your _(some)_ traditional speargun(s), to a roller. One of the problems with traditional spearguns is that they don't use the full length of the stock, they generally only transfer energy to the spear over some 2/3s of the full length, and when they do they go from transferring 100% of the energy to 0%, meaning that the energy curve is rapidly declining. Then you can add another set of bands, and that _does_ give you a decent amount of extra energy, but it _also_ increases the already rather substantial recoil. Roller guns however, never let the bands contract to 0%, because the bands are either pre-stretched or as in the case of my first gun, also boosted after loading with 2 sets of booster bands. So, energy transference-wise, they go from some 150% or more down to maybe 50% at the point of release, I haven't done the exact math on it, but it's in the ballpark. As for recoil, I'd say a roller only has about 60% the recoil of a similar length traditional speargun. I would recommend you look into this type of speargun, clearly you are a skilled craftsman, so it shouldn't be too hard for someone like you to adapt a speargun roller system to suit your needs, or at the very least reuse the technology for something besides hunting fish underwater. I reckon you could easily shave those wheels down to around 35-40mm in diameter, and thus get a much sleeker result, on a roller gun the wheels are upright, the pull comes from the underside as the spear is pulled by the "wishbone" on the upper side of the wheels. On a roller gun we need a couple of string risers at the end of the stock because our spears aren't pulled from the end, but from a groove or "shark fin" located a bit up from the back end of the shaft, where it goes into the trigger system, but you won't have to worry about that. Most traditional spearguns around my part of the world are either what we call "75'ers" or "90's" as that's the band pull measured in cm, the shorter ones are primarily for hunting around structures, whereas the longer ones are better for open water. My main gun is a bit shorter than a "75", but shoots like a "110", so there is a lot of length to be saved with a roller gun design. One of the greatest features, in my mind at least, is that you can add several boosters without increasing recoil significantly. Anyway, if you decide to have a go at new crossbow, feel free to ask anything, I've built a bit of this and a bit of that over the years, and I might be able to answer some of your questions.
Very nice proof of concept. I think there are many more mechanical advantages that can be applied to maximize the usefulness of such a small bow. The fact that you got it to the point it currently is with such a small overall size just leaves that much more room with which to add upgrades/improvements.
2 года назад
Welcome my friend, I like the design and the power too. I am also considering building a spring gun but I don't have a specific plan yet ..... The pistol grip and shoulder rest are good. I would add two things to the gun: -With a sight to shoot accurately at a distance. -I would put the springs in a thin-walled metal tube (say it looks good in a brass tube) to make it safer. if you touch the spring you can pinch your skin when shooting. The springs are close to your hand. Congratulations to.
Thank you, Lacás! Yeah, there could be many things improved upon, including safety for the fingers. I thought about a sighting system, but wanted to finish this thing and didn't came to do it. In the next version though, for certain.
2 года назад
@@aurigo_tech these are just small additions .... I'd either mount a little reddot on it or make a simple viewer of it. I might emphasize the post’s apolaliptical or steampunk design.
@ Может быть, это то, что ты ищешь: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-RuOYf-plI9M.html
2 года назад
@@Ге.Нов Hi This is not bad. The structure is well hidden. I would love to see a video of it showing its accuracy and power. And the firing range should also be specified... This is my comparison video of my weapons: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-qGar8wid0Hs.html The telescope mount is not good because it is fixed at only one point, and several times it can be seen that the telescope is tilted to a large extent compared to the center line....
Sweet design mate! I really liked your draw length multiplication, simple yet effective. It also looks like it shoots smoothly with very little hand shock, well done!
As an Australian without ready access to Orangina, I'm furious! Furious that you would waste my favourite drink! But I do love the crossbow design. So I suppose I'll let it slide haha. Great job!
I must admit it was a grave mistake to shoot a very suggary drink - I thought it looks nicer on camera because it has some colour - but also it's sticky as hell and I had to clean myself, the camera and tripod afterwards :)
I'm glad he mentioned using a compound crossbow-like system. A smaller, compound wheel/pulley system could reduce the profile. Might even be able to fit all of it within the body of a crossbow
Very good design! I'm a little bit of a fan of the idea of using metall springs as parts of crossbows, and so it's very nice to see that you have so many new ideas to enrich the design of these devices! Thumbs up and subscription added. ;-)
Ausgezeichnet!! I would not have guessed that any of those parts were 3d printed. It would be lovely to see a skeletonized 3d printed frame, too, if it would be strong enough. Very nice work!
Thanks! Usually the wheels broke along the outer shell from too much compression of the string, so I thought 100% infill should pretty much remove that issue and it did. Perhaps it is also sufficent to just increase the thickness of the outer shell and have 25% or so infill otherwise. A 3d printed frame would definitely be strong enough if done right, meaning spreading forces over larger areas. However, as a next step I want to further improve on the principle and have more power/speed etc. Relatively soon there will be the next version of the spring bowered bow for that reason.
@@aurigo_techcertain parts I wouldn't skimp on weight and quality even using metals were you didn't want but the skeletonized frame sounds good to make up for that gain .with plastics and carbon it doesn't take long for friction to start wearing down pieces especially were string is running and arrow is running against a surface . It's a nice thing almost steam punk looking
Funny thing,you brought up the trampoline springs for your main source of draw energy. I'm starting a small business making and selling "trench" style weapon systems and other stuff in that realm, I am only using things that I have found or bartered for in order to aquire the parts. I just happened to get almost all the springs off of an old, busted trampoline. SCORE!!!
Three obvious things that can improve the system: use eccentric cams to let off the spring force - this will even the force and make steady the acceleration curve, promises up to 50% improvement when balanced correctly to the weight of the bolt; do not use extra passive rollers - I recon you lose up to 20% of energy in them just for the sake of springs moving in parallel to the stock; synchronize the string pulleys, 20-30% of energy loss here, the easiest is to use one spring and distribute it into two cams. With all of those you may practically double the energy. Further, the bolt weight must balance with the weight of the spring, roughly it should be equal to the weight of the spring divided by two roller ratios (because only half of the spring moves "on average"). You may improve the system even more by using an air spring, e.g. from the spear gun using a carbon fiber drive rod.
Good points! Most of which I was aware already. Some things are hard to combine though in one device. For instance to have one large spring but also no rollers to redirect the string - I can't really see how that would be possible without adding new components which increase drag/losses again. According to my calculations this crossbow converts just under half of the energy stored in the springs into kinetic Energy of a bolt. And yes I am sure I can increase that ratio. I will add non-circular cams next, as well as remove friction losses like the redirectional rollers and some other mentioned things, like improved adjustability. Thanks for watching and giving an excellent analysis!
@@aurigo_tech Glad that we are thinking in cohort! A single spring can pull a Y-shaped wire distributing force directly to the cams, synchronizing them at the same time. I am trying to source a decent air spring, too bad that spear guns are totally banned in Canada. Another interesting direction of thought is torsion springs - those are the most energy-rich ones with he least amount of "attached mass" (carbon fiber, possibly?). They work exceptionally well in high-ratio pulley schemas.
Replace your coil springs with high grade nylon monofilament, extending right back in grooves to the back of the stock. It has over 140% original length yield strength and the highest energy storage per weight in tension of any common material. Run it directly to wind up spools directly on your throw wheels. If you offset the centre of rotation on the throw wheels and reduce friction by having them offset forward and unwind the throwstring directly at their rear, and preload the nylon tension cords, then you can easily achieve a constant force and acceleration over the whole throw of the Arrow. Then you will have a world leading crossbow in power and accuracy.
@@jazon9 I actually had both materials work. I felt more comfortable with PETG though, because it is less brittle and I think it absorbes shocks from sudden accelerations (or decelerations), like the wheels do, better. Apart from user error on my side (by dry firing it once) they didn't break on me yet.
Awesome project, I too am designing a spring powered bow with my son as one of his uni ideas, the latest designs have internal springs and vertical wheels, but I still like the traditional bow look, but want the adjustability of a spring, so have gone for a double actuated knuckle at the front, won't be as powerful, but as with you, it's an experiment Look forward to your MK3 version, will be very cool ; )
If you make your parts with 20% to 30% infill and lots of little holes on the surface, then you can paint them with resin which will soak in and make them very strong. Or if you make them very thin and then paint them with resin, and then dip them in graphite fiber (or baking soda), let them dry, then paint them in resin again and dip them in graphite fiber (or baking soda) again. Repeat that until they are as thick and strong as you need them.
This is exceptional. I watch allot of self-made irregular crossbow concept videos and hence was expecting something that can tickle styrofoam. Instead, here is something that would stain Yogis underwear. It puts out enough energy. Next up. Gas pistons?
Thanks! Yeah it could poke a nice hole in many things. Right now I am working on the coilspring powered bow Mk III, as a test for the next version of this crossbow. There I focus on improving the wheels to non-circular cams, among some other improvements. Unfortunately life is busy so I always take too long to make new versions.
A new JOERG SPRAVE is born, thanx God, finally. Tatsächlich hab ich auch viel über Federn nachgedacht, Klasse vor allem mit der Übersetzung, dass man praktisch den geringen Zugweg der Feder so beliebig verlängern kann. Auf die Idee muss man erstmal kommen, scheint mir das beste an der ganzen Sache. Weiter so
Ja es trennt halt Energiespeicherung und Energieübertragung (auf den Bolzen) voneinander. Beim normalen Bogen/Armbrust ist das beides im Bogen vereint, was auch seine Vorteile hat natülrich. Aber wenn man es voneinander trennt, kann man auch beides getrennt kontrollieren/manipulieren.
nice design although i would add longer spring that go direct on two assymetrical egg shaped wheels and make them slightly smaller .... that would be insane
Instead of using more powerful springs, move the existing ones back so they are more pretensioned, som you gain the additional force over a longer length of the draw. And like you said, change the shape of the wheels to adjust the force profile in different parts of the draw. Very cool!
Really novel idea. You could probably use a toothed rack attached to one spring to drive two pinions and use those to drive the wheels, then you might be able to house only a single big spring inside the stock of the crossbow rather than two on the outside.
Thanks mate! I will keep working on this idea. I have already developed it further as a bow and made a video about it. And I have even more ideas for the next crossbow as well. If only I had more time to work on this stuff..
In one of my undergrad journals from the early '90s I have a design for a spring powered crossbow very much like that, but a little more compact, but essentially the same. Never got around to making it though, too many other things to do.
it's not a Ravin R500 or a Ten Point Nitro 505, but you did a great job and in any case, I wouldn't want to find myself in the path of your arrows! congratulations, I think you have the potential to improve your product even further
@6:42 That apple be like "Crossbow bolt ain't sh!t now again! I said again!" little did we know that apple was in a doping scandal a year ago no wonder he took like a champ.
Those springs are kinda where the stabilizing hand goes on the forestock. One normal xbow maker uses wing shields halfway horizontal across the forestock to keep fingers from creeping up. I would suggest polished overlapping sleeves, two part where one slides into the other. You may not have seen that design executed due to perceived or actual danger/liability.
That is a very nice looking crossbow, good job! I think this would look even more awesome when given a little bit of a steampunk / Victorian makeover, or to keep it German, Bavarian. By which I mean less plastic and more brass (for the gears and cover) and darker wood. Aber es sieht so wie es ist sehr schön aus!
Thanks! Yeah the looks could definitely be improved. But keep in mind this is still a proof of concept kind of thing. Looks were definitely not one of my priorities. There will be a next version soon-ish (relatively speaking, for how slow I sometimes produce videos :D). I will definitely improve the looks there somewhat, even though that will also still have a focus on improving the functionality.
Not sure how to calculate the most efficient acceleration profile, but as you say you could certainly include excenter profiles on the wheels, BOTH ends. The spring pulls the hardest as maximum stretch and a lot less near end of power stroke, could pay off to use an excenter profile on input wheel too, might need to step up the radius near end of spring movement to be sure it can actually add energy and not coast along at the end of spring contraction. Not sure if it pays off to have a smooth start acceleration curve or just start as violently as possible. Normal "compound" is to introduce a lower let-off force, slower start, but that is mainly I believe to compensate for human "issues". There are alot of simplifications that can be made by putting wheels vertically, like all wheels can be fixed on one thru-hole axle. That will however make excenter wheel design problematic as it would induce a wobble in Z-axis... that may lead to an extra support/guide wheel to eat up the variation but at a price of complexity and losses in power. I'm amazed that the plastics stand up to these forces!
Cocking aids are essential in home built toys. One of the first times I cocked a slingbow I got my fingers stuck. Not a little bit either, the cord cut me up, it was pressing so hard on my pointer fingers against the stock. I was stuck for a few. It was temporary. I have to use a rope with more bands.
درودبرشما خیلی هم ممنون از این تير کمان خوب دم شماگرم موفق باشید امیدوارم که یک گوزن نر یا یک گراز پرگوشت شکار کنید اون هم با اجازه محيط زيست که برای شما مشکلی پيش نیاد مؤفق پيروز باشید🙏🙏🙏🙏
Great design, and good to see some fresh thinking. I wonder if a pneumatic spring might be a thing? It would take a bit of designing, but being able to change the draw weight by a pressure adjustment seems worthwhile.
gas spring has some advantages, but it's very overrated by airgun producers, main advantage is that there is no that annoying sound after you fire like you play some music instrument and second, it doesn't get weaker over time.
I was thinking that if you designed it carefully, the gas spring could give a much flatter draw curve. A mechanical spring is a Force proportional to stretch so the thrust force on the bolt drops away as it moves out of the bow. But with a gas spring that wouldn't necessarily be so, you could potentially have the same thrust on the bolt for the entire stroke or close to it. Also being able to dial in just how much thrust you want to give to the bolt seems like a plus too. I don't know how to do this, I do electrical stuff, but I 'd love to be able to build something like this.
You can thead a hole in the middle of the bolt holding the springs and then put a threaded rod through it, in the middle of the stock. Fix the rod at both ends, attach something to turn it (like a knurled wheel or an attached ratchet wrench) and cut some slots for the spring holding bolt to move back and forth. Now draw weight would be adjustable while the draw lenght stays the same. Lots of added complexity but you could also use it to load the bow by adjusting it down to hand draw levels and then ratcheting it up all the way back up again.
This is genius. I have a couple of similar springs lying around and have been thinking of using four or more pulleys to increase the draw length and to possibly allow lighter arrows to be shot faster and therefore on a flatter trajectory. I think this system could achieve the same thing. I wouldn't have thought of doing it this way. Well done. I look forward to the next generation of this design. P.S. there is a video on RU-vid of a supersonic trebuchet. Do you think bows can be pushed to be supersonic?
Thanks! As mentioned I will certainly follow this with improvements and see where it goes. I have seen the supersonic trebuchet, but I think it is not really feasable for a hand held crossbow like version. At least not when you want to use more or less ordinary bolts or projectiles with a usual weight. However, the cutting edge of "normal" crossbows already reaches 1/3 to 1/2 of the speed of sound, and I think we are not at the end of development yet.
Great design! According to the numbers you give, efficiency is only about 40%. Perhaps the pulleys should be lighter? A promising design, and hope you develop it further.
Thanks! I already did - check out my latest video about the coilspring powered bow, which uses the same springs as this one and the same basic system but further developed. I will also do another crossbow next.
WOW ! I had kind of the same idea but never did made it to work. It is very slim and I bet you could make it even more slim by stacking the cams. GOOD JOB ! 👍👍👍👍
Nice design well thought out , just be careful not to get a finger pinched by one ofthe coils when fired , saw a design where it had a plastic tube covering the springs to prevent that from happening.
You can actually get rid of the two wheels closest to the spring and connet the spring cord directly to the underside of the big wheel axles. Your springs would angle away from the weapon body by around 15° so won't look as cool, but it's simpler and it reduces friction just a little bit.
For a magazine mechanism and a more automatic reload, a revolver gun concept could work. Also, would be great to put some sights on it, even a scope, with a porting from the side or something
This seems to utilize the same mecanism as the spring loaded bear trap. and springs takes way less space than limbs. And icredibly easy to add more power, just put in stronger springs. migt try my luck with making on at some point.
Interesting. I never looked at bear traps in that regard. I will look into them and see if there is something to learn from it (often those simple mechanical devices indeed contain much more genius than is obvious on first sight).
Hmmmm ..if you use springs or rubber strings or bands it wouldn't be any issues on dry fire or having it as a slingshot too...if you use fg limb or wood etc you might have a problem when dry fire or use not compatible arrow or ball bearings...still it is awesome ideas!!!👍💕👍keep it up ... following
Есть ли идеи по модернизации данной конструкции, а именно: эксцентриковые блоки и система булпап? Ещё можно попробовать скомпоновать блоки вертикально, что сузит ширину, но усложнит конструкцию. При испытании на скорость использовался тяжёлый 30 граммовый болт, что выдало результат в среднем 40 м/с. Если использовать более лёгкий болт в пределах 15-20 граммов, то насколько увеличивается скорость в м/с? И ещё, способна ли выдержать конструкция арбалета выстрелы шариками, так как они могут быть слишком лёгкими, и критично ли это для надёжности? Есть ли идея реализовать подобное?
A good design. But the following small ideas. Consider a double spring? a bigger spring with a smaller spring inside? It maight make the pulling faster. Did you consider making the big wheels excentric? Maybe faster.
What are your thoughts on using a vacuum piston as your power source? There are a few relatively old videos of a guy who made something like that and frankly, its impressive if its real. But your design can improve it greatly, I think. I would very much like if you could watch those clips and share your thoughts. Perhaps even explore realizing the idea in the future? The channel in question is 'Pylenok'
I don't have any experience with these vacuum pistons. I see potential issues with leakage and would generally question how fast these are. No doubt a vacuum would pull back with enormous force, but the amount of grease he had to put in there tells me there is probably a lot of friction to overcome, which would make it slow. But again I have no experience with these and would need to look closer into it. Unfortunately he has no shot over a chrony as far as I can tell, so its hard to judge the true power of these (especially considering that zylinder is huge - compared to the relatively small springs I have).
@@aurigo_tech You can only kind of judge the speed by the sound of the bolt, if he actually gave correct distances. I brought it to light because you can easily print the piston to really fit well to any tube you can acquire and cause its right up your alley :D
What about using a "pulling gas spring" instead of coil springs? Saw some in mcmaster carr catalog up to 250 lbs each. Or some type of adjustable pneumatic springs like the ones used in some breakbarrel airguns, like my ancient beeman rx1. The ratio of the string wheels to the spring wheels is a nice idea to reduce the draw weight which is always an issue with the more high powered crossbows. Keep up the good work!
Yeah a lot of new stuff in recent years. I think a large factor to bring innovation into existence even in long established fields like archery is also modern materials, design and manufacturing methods like CAD, 3D-Printing or CNCing. I think other fields hold a lot of room for improvement as well for the same reasons.
