the problem with accuracy may be that the wheels/springs are not synchronized, either the left or right spring might just pull a little faster than the other thus the back of the arrow is pulled slightly to the left/right by the string upon release. my suggestion is to put both springs in parallel (or a single stronger one)under the stock and just have one attachment point to the springs for the cord that goes to both the small lower wheels. Hope you can understand what I mean. regardless of the method employed , you need both the wheels recieve the exact same amount of "pull" at the same moment. thats hard to do with two individual springs /connections. otherwise a very interesting crossbow. keep up the great work!
Yours reminded me a bit of the early crossbow form channel "pylenok" not the very best video quality but you can see he uses a single spring under the stock. But yours has mechanical advantage because oft the small/big wheels which makes it faster .th-cam.com/video/he6zA5MTMuo/w-d-xo.html
Good thoughts! A single larger spring would require a totally new design, so I won't be able to change that here. The springs themselfs seem very consistent to me, so I think the problem is rather the connecting strings to the wheels. Those are of course individually made and slightly different in length. To compensate I have to twist them a bit and I think when exchanging the right wheel for repair I didn't pay enough attention to that.
I built a ballista with torsion bundles. It is kind of tricky to get them both adjusted to the same tension so that the bolt flies straight. On a more recent machine I used a single axle to drive the bow string so hopefully it will eliminate that issue. I think it might be happening on yours. Maybe if your smaller pulleys had gear teeth so they had to rotate the same amount? Nice build.
These crossbow videos are very interesting! I hope to see more on spring crossbow improvement!
2 ปีที่แล้ว +12
Hi friend. The first sighst is very good. The stirrup is also very good. It is not good to mount the rear sighst on a moving part. although I can see that you couldn't put it anywhere else because of the pull-up. I would rather have solved the height adjustment with a longer vertical notch with divisions. In the case of lateral movement, the nut screw can also become loose due to vibration....
Yeah I didn't really had another spot to mount the rear piece. But the flat spring can be moved quite accurately into the middle because it is exactly as wide as the side plates of the trigger group, so one has a visual indicator and it won't be wildly off. But yes, not ideal. I will consider this topic in the next new build.
@@aurigo_tech maybe consider a physical stop so the bolt retainer always returns to the same spot. Like a small raised portion the spring cannot turn past. Keep going man this is the coolest spring crossbow I've seen!
@@bobhatesrainbows Thanks! And yeah in a next version I will definitely rethink that whole area at the back with the flatspring and the aiming system and replace it with something more integrated instead of the afterwards addition kind of thing it was here.
For rear sight. use an 'L' shaped piece of metal. the Long part of the L bolted to the left side of the stock. the short part of the L is over the clasp. On top of the L can be used for a picatinny rail, and then boundless options. If you don't want a picatinny rail you have solid flat place to add bolts to make a simple sighing system. You probably need to use 'string stops' to stop the string coming off.
Yes, maybe the 2 wheels are running unevenly. Possibly one central spring could drive both wheels to make them more synchron ? Never the less I like the concept very much ! 👍 Ach, noch eine Frage: Warum wird die Sehne an den kleinen Rollen nochmal durch eine weitere Rolle umgelenkt ? Die könnte doch eigentlich auch direkt auf die eigentliche Rolle gehen, oder ? Ich denke, daß durch die Umlenkung, unnötig Energie verloren geht.
Ja mit einer Feder könnte man es sicher einfacher synchron bekommen, aber das beschränkt auch die mögliche Bauform denn die Feder muss ja in der Mitte liegen, während ich mit zweien links und rechts mehr Platz hatte (und auch noch größere hätte montieren können). Die Umlenkrolle ist da um die Federn parallel zur Armbrust zu haben und sie dann leichter befestigen konnte. Bei einer nächsten Version verbinde ich sie direkt ohne Umlenkrolle. Ich arbeite im Moment an einem weiteren Bogen nach diesem Prinzip und da kommen diese beiden Themen direkte Verbindung und Synchronität auch vor.
The sights are on the bolt holder which you move to the side when cocking the crossbow. This affects windage, so does the nut since it can spin freely here and then. However these upgrades make a difference. I'm very impressed by the power of this crossbow.
Yeah well, I don't really have another mounting point for the rear part of the sights. The width of the bolt holder is exactly 20 mm, which is the same as the width of the alu plates of the trigger group directly underneath it; so its fairly easy to line up. But yes, not ideal and I will improve that among other things in the next version.
I’ve often thought about a spring powered crossbow but using one powerful spring internally. Maybe a square tubular aluminum frame. I’m sure it would be possible to have one cable pulling straight back connected to the pulleys?
If you switch from your current loading aid to something with a lanyard and double hook some of your issues will be reduced. Swinging the arrow holder every time you load with the rear sight on it reduces the usefulness of the sight. A quick search of the web will show you the loading aid I’m talking about. With it you can stop swinging that arm. Someone else here in the comments questioned the weight balance of the springs to pulleys. They’re a hundred percent correct, that can and will play a major roll in your accuracy. It shouldn’t be to difficult to work that out
Well you are right - the sights were a pure add-on and I am aware they don't represent the ideal solution. In a next version I will integrate them into the design from the beginning. Same thing with the cocking-aid. I initially planed to just draw it back by hand, but that turned out too difficult due to the narrow angle the string forms when fully cocked - it became quite painful on the fingers and was just not possible to get them out again. So I had to make this simple improvised aid-thingy - again in a next version I will make an integrated system, perhaps something similar what I had on a older crossbow I build a few years ago. The issue with the possibly unbalanced springs is the length of the strings - it is very hard to make them exactly the same length. I did my best and they are really close, but even a millimeter makes a difference. Also the holes for the main axle on one side to the other is perhaps off by less then a millimeter, but still enough to possibly cause some issues. Not to mention I can only adjust by twisting or untwisting the string, which is not super accurate. I am aware of this issue and working on solutions for better integrated adjustabilty already.
@@aurigo_tech tensioning the springs really isn’t that difficult. Thinks of incorporating something like a cable tensioner into it. The idea I have would incorporate any eye bolt letting your apply a hand held fish scale to measure spring tension and adjust as necessary.
Why couldn't you have the springs further forward rather than use the wheels? If the wheels are essential, could you place then inset into the stock (one on top of the other) so that the overall profile is slimmer), or rotated 90 degrees so that they run parallel to the stock of the bow?
The wheels are necessary as a device for archieving mechanical advantage. In principle the springs could be placed elsewhere as well, sure. But I found this position next to the stock to be the most convenient for me.
I can place the flat spring very easily in the middle, because it is exactly as wide as the two alu plates of the trigger group beneath. But yes, in a follow up version this will be improved.
Is it possible to advise about the spring you used in the crossbow? How to prepare this spring? Or what are the specifications of the spring? How strong is it?
The exact ones I used are 13.4 cm total length, 2.65 cm total diameter, 4 mm wire thickness, 25 windings each. And they are rated for 52 kg max weight, but they can be drawn out further, I put on roughly 60 kilos of draw weight on them. I knew the rough mechanical advantage of ~1:4 beforehand so I ordered some springs online that still fit into the crossbow while I will still be able to draw them out.
It looks like the draw weight is really high, I would guess you could lower the resistance weight of your tension springs and still shoot the bolt the same speed. By the look at those springs and set up, looks like more than an 80lb draw. You could shoot some heavy ammo with it! Its not the draw weight but the speed of the string that you need to work on.
The upper larger wheel (where the main string wraps around) is connected via a shaft in the middle to the lower smaller wheels where the string for the springs wrap around. To transfer the torque/torsion-force between the shaft and the wheels I cutted slots into the shaft and fitting slots in the wheels as well where a key inserts (essentially a small 20x20 mm steel plate). That way the upper and lower wheel can not rotate independent of each other.
@@claudioambro6313 No there is separate strings. Shorter ones that attach to the springs and smaller lower wheels and one large main string that shoots the arrow. Check out my other videos on this crossbow, it explains a lot.
@@aurigo_techfor other videos do you mean the crossbow upgrade? I looked at them all but either you didn't explain it or I can't understand. but why didn't you connect the rope directly to the larger pulleys?
love the creativity. this is infinitely more practical than all the overpriced crap out there. good job. You deserve more subs.
the problem with accuracy may be that the wheels/springs are not synchronized, either the left or right spring might just pull a little faster than the other thus the back of the arrow is pulled slightly to the left/right by the string upon release. my suggestion is to put both springs in parallel (or a single stronger one)under the stock and just have one attachment point to the springs for the cord that goes to both the small lower wheels. Hope you can understand what I mean. regardless of the method employed , you need both the wheels recieve the exact same amount of "pull" at the same moment. thats hard to do with two individual springs /connections. otherwise a very interesting crossbow. keep up the great work!
Yours reminded me a bit of the early crossbow form channel "pylenok" not the very best video quality but you can see he uses a single spring under the stock. But yours has mechanical advantage because oft the small/big wheels which makes it faster .th-cam.com/video/he6zA5MTMuo/w-d-xo.html
Good thoughts! A single larger spring would require a totally new design, so I won't be able to change that here. The springs themselfs seem very consistent to me, so I think the problem is rather the connecting strings to the wheels. Those are of course individually made and slightly different in length. To compensate I have to twist them a bit and I think when exchanging the right wheel for repair I didn't pay enough attention to that.
have you tried adding a short barrel, like 20 cm long, starting from the front sight. narrow barrel. it may stabilize the arrow flow..
I built a ballista with torsion bundles. It is kind of tricky to get them both adjusted to the same tension so that the bolt flies straight. On a more recent machine I used a single axle to drive the bow string so hopefully it will eliminate that issue. I think it might be happening on yours. Maybe if your smaller pulleys had gear teeth so they had to rotate the same amount? Nice build.
These crossbow videos are very interesting! I hope to see more on spring crossbow improvement!
Hi friend.
The first sighst is very good. The stirrup is also very good. It is not good to mount the rear sighst on a moving part. although I can see that you couldn't put it anywhere else because of the pull-up. I would rather have solved the height adjustment with a longer vertical notch with divisions. In the case of lateral movement, the nut screw can also become loose due to vibration....
Yeah I didn't really had another spot to mount the rear piece. But the flat spring can be moved quite accurately into the middle because it is exactly as wide as the side plates of the trigger group, so one has a visual indicator and it won't be wildly off. But yes, not ideal. I will consider this topic in the next new build.
@@aurigo_tech maybe consider a physical stop so the bolt retainer always returns to the same spot. Like a small raised portion the spring cannot turn past.
Keep going man this is the coolest spring crossbow I've seen!
@@bobhatesrainbows Thanks! And yeah in a next version I will definitely rethink that whole area at the back with the flatspring and the aiming system and replace it with something more integrated instead of the afterwards addition kind of thing it was here.
For rear sight. use an 'L' shaped piece of metal. the Long part of the L bolted to the left side of the stock. the short part of the L is over the clasp. On top of the L can be used for a picatinny rail, and then boundless options. If you don't want a picatinny rail you have solid flat place to add bolts to make a simple sighing system.
You probably need to use 'string stops' to stop the string coming off.
i thick a single spring divided over 2 vertical wheels seems like a great idea
Yes, maybe the 2 wheels are running unevenly. Possibly one central spring could drive both wheels to make them more synchron ?
Never the less I like the concept very much ! 👍
Ach, noch eine Frage: Warum wird die Sehne an den kleinen Rollen nochmal durch eine weitere Rolle umgelenkt ? Die könnte doch eigentlich auch direkt auf die eigentliche Rolle gehen, oder ? Ich denke, daß durch die Umlenkung, unnötig Energie verloren geht.
Ja mit einer Feder könnte man es sicher einfacher synchron bekommen, aber das beschränkt auch die mögliche Bauform denn die Feder muss ja in der Mitte liegen, während ich mit zweien links und rechts mehr Platz hatte (und auch noch größere hätte montieren können). Die Umlenkrolle ist da um die Federn parallel zur Armbrust zu haben und sie dann leichter befestigen konnte. Bei einer nächsten Version verbinde ich sie direkt ohne Umlenkrolle. Ich arbeite im Moment an einem weiteren Bogen nach diesem Prinzip und da kommen diese beiden Themen direkte Verbindung und Synchronität auch vor.
The sights are on the bolt holder which you move to the side when cocking the crossbow. This affects windage, so does the nut since it can spin freely here and then.
However these upgrades make a difference. I'm very impressed by the power of this crossbow.
Yeah well, I don't really have another mounting point for the rear part of the sights. The width of the bolt holder is exactly 20 mm, which is the same as the width of the alu plates of the trigger group directly underneath it; so its fairly easy to line up. But yes, not ideal and I will improve that among other things in the next version.
Great besta! I am learning a lot with your videos and I hope to construct a good one! Greatings from Brazil!
I’ve often thought about a spring powered crossbow but using one powerful spring internally. Maybe a square tubular aluminum frame. I’m sure it would be possible to have one cable pulling straight back connected to the pulleys?
If you switch from your current loading aid to something with a lanyard and double hook some of your issues will be reduced. Swinging the arrow holder every time you load with the rear sight on it reduces the usefulness of the sight.
A quick search of the web will show you the loading aid I’m talking about. With it you can stop swinging that arm.
Someone else here in the comments questioned the weight balance of the springs to pulleys. They’re a hundred percent correct, that can and will play a major roll in your accuracy. It shouldn’t be to difficult to work that out
Well you are right - the sights were a pure add-on and I am aware they don't represent the ideal solution. In a next version I will integrate them into the design from the beginning. Same thing with the cocking-aid. I initially planed to just draw it back by hand, but that turned out too difficult due to the narrow angle the string forms when fully cocked - it became quite painful on the fingers and was just not possible to get them out again. So I had to make this simple improvised aid-thingy - again in a next version I will make an integrated system,
perhaps something similar what I had on a older crossbow I build a few years ago.
The issue with the possibly unbalanced springs is the length of the strings - it is very hard to make them exactly the same length. I did my best and they are really close, but even a millimeter makes a difference. Also the holes for the main axle on one side to the other is perhaps off by less then a millimeter, but still enough to possibly cause some issues. Not to mention I can only adjust by twisting or untwisting the string, which is not super accurate. I am aware of this issue and working on solutions for better integrated adjustabilty already.
@@aurigo_tech tensioning the springs really isn’t that difficult. Thinks of incorporating something like a cable tensioner into it. The idea I have would incorporate any eye bolt letting your apply a hand held fish scale to measure spring tension and adjust as necessary.
Thank you for your video!
Thank you sir!
Why couldn't you have the springs further forward rather than use the wheels? If the wheels are essential, could you place then inset into the stock (one on top of the other) so that the overall profile is slimmer), or rotated 90 degrees so that they run parallel to the stock of the bow?
The wheels are necessary as a device for archieving mechanical advantage. In principle the springs could be placed elsewhere as well, sure. But I found this position next to the stock to be the most convenient for me.
You mounted the sihts on a mowing part?😅
I can place the flat spring very easily in the middle, because it is exactly as wide as the two alu plates of the trigger group beneath. But yes, in a follow up version this will be improved.
Is it possible to advise about the spring you used in the crossbow?
How to prepare this spring?
Or what are the specifications of the spring?
How strong is it?
The exact ones I used are 13.4 cm total length, 2.65 cm total diameter, 4 mm wire thickness, 25 windings each.
And they are rated for 52 kg max weight, but they can be drawn out further, I put on roughly 60 kilos of draw weight on them.
I knew the rough mechanical advantage of ~1:4 beforehand so I ordered some springs online that still fit into the crossbow while I will still be able to draw them out.
you should try to get rid of the "idler" in your pulley system and attach the springs directly to the cam; idlers waste a huge amount of energy.
the sights would be stationary and not move from a set position and the latch would also be moved little for quick reloading
Amazing!
It looks like the draw weight is really high, I would guess you could lower the resistance weight of your tension springs and still shoot the bolt the same speed. By the look at those springs and set up, looks like more than an 80lb draw. You could shoot some heavy ammo with it! Its not the draw weight but the speed of the string that you need to work on.
Nice one evil twin :D
Дуже класна ідея, всі вірно мабуть часу не було зробити підрахунки прицілу. І та теж дуже добре в шляху підрахується.
🤙💃
How does the rope get from the smaller pulleys to the larger pulley? there being a different height. Please reply this comment
The upper larger wheel (where the main string wraps around) is connected via a shaft in the middle to the lower smaller wheels where the string for the springs wrap around. To transfer the torque/torsion-force between the shaft and the wheels I cutted slots into the shaft and fitting slots in the wheels as well where a key inserts (essentially a small 20x20 mm steel plate). That way the upper and lower wheel can not rotate independent of each other.
@@aurigo_techthankyou for the reply. So the rope passes through the outermost pulley and reaches the larger one? can I buy these things?
Could you do a mini tutorial on how the crossbow works, such as the release mechanism, springs, pulleys, etc.? (if you can)
@@claudioambro6313 No there is separate strings. Shorter ones that attach to the springs and smaller lower wheels and one large main string that shoots the arrow. Check out my other videos on this crossbow, it explains a lot.
@@aurigo_techfor other videos do you mean the crossbow upgrade? I looked at them all but either you didn't explain it or I can't understand. but why didn't you connect the rope directly to the larger pulleys?
Not bad shooting with iron sights at all.
You need to attach a scope on it.
Yeah, I could, but I like the DIY aspect of the selfmade "iron" sights more. Fits the overall theme of the channel much more as well.
Instale um nívelador 🤓
你的弩非常优秀简洁，很有创新，射程有多远呢
Thanks! If I aim 45° degrees upwards probably around 100 m. But hitting something then is another question..
Thank you sir!