Twin Axle Trigger System
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- Опубліковано 5 вер 2017
- Showing the parts and working of the late medieval/renaissance twin axel trigger system used on crossbows
The earlier single axle rolling nut • Single axle rolling nu...
The cranequin crossbouw that uses the twin axle system • 16thC hunting crossbow...
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like others have pointed out, the sear axle seems to be positioned in such a manner that it would actually increase the load on the trigger. It should be closer to the rotating nut with a longer lever towards the trigger itself.
Thank you sooo much, Tod! Spared me a ton of trial & error to figure it out by myself! Nice job!👍
I wondered what that little poking stick was about in the other hunting crossbow video!
Hi Tod, can you compare different crossbow trigger mechanisms from around the world? Crossbows from ancient China had a hook style trigger mechanism mechanism made from cast bronze. The tribes in South East Asia had very simple crossbows that sometimes didn't even use metal parts. The earliest European crossbows (eg. Greek Gastraphetes) had a strange slider lock thing. I'd be interested in comparing the advantageous and disadvantageous of different crossbow types and their trigger mechanisms from around the world.
Yes please
I made a video about Chinese crossbows
Great video. Please continue making them. Very informative
This is truly interesting and educational.
Awww now I get it! I truly learned something today.
well done. I learned a lot. Thank you Tod
Thanks Tod. I changed from a single rotating cam with associated trigger to a lift string above notch in barrel method of triggering the light hunting medevial style crossbow I assembled totally from scratch which included turning a tree into planks. I simply did not like the force applied to the trigger which made firing it less than fun. The method I used needs attention to detail too otherwise you lift the tail end of the bolt. The system you showed here looks fabulous.
Sweeet info, thanks for this brother
Geniale.......veramente bravo
Can you make a video on how to make those wooden flights
Hi Tod, I already responded earlier the reason I thought why they added the poking stick!
Great video Tod. Is this what is called a "clap lock"? I watched one of your videos where the bow used a clap lock system. Cannot find much of anything online.
The Roma’s had an awesome looking trigger system as well, how long did it take to machine the parts?
Agree that the hingepoint of second axle is positioned on the wrong side, giving relatively unnecessary loads of pressure on the main lever. I would make a positioning pin on the nut to prevent it from over ratation, and a spring on the second lever so no fiddling with pins for loading is needed. Still a great mechanism though!
I would say amazing for the time it was made.
Have you made one like.
Interesting. Never thought such a system even existed, I was always assuming the single axel system was the one and only widely used mechanism.
I imagine that the rotating nut trigger remained the military crossbow trigger system of choice not just because they were cheap and easy to manufacture but also because they were robust and reliable under campaigning conditions, where they were likely to get wet and dirty and still needed to work properly every time.
I think you are right; unsophisticated, but bomb proof
hmm that sear tough.. from the pin location i can tell that its eater change nothing or actually increase the force on the trigger piece. That pin should divide that sear at least one third to two third ratio. Being the one third one on the top side.
Peter Moritz to gain a mechanical advantage. this makes some sense. I'd be interested in trying to build this myself soon. right now I'm browsing all possible trigger configurations, and sorting them to find a relativly good compromise between being easy to produce with minimal tools, and materials, and reliability. in this regard, the original lock still seems more suitable. plus I'm not trying to build a seige bow lol. just a hunting crossbow for up to medium to large game. this has been a challenge, and though I made a few working prototypes, none satisfy my criteria. still, this might be something to build off of. never know. I can't see needing a trigger to support more than 100# draw. anything beyond that I think is excessive, and leads to further mechanical challenges that could be avoided. pretty sure 100# or less is enough to hunt with. and building a stronger prod in a survival situation is a stretch.
Richard Peterson be advised that because of the very short travel distance of the string, a 100lb crossbow will actually be very under-powered. For instance an 800lb cross bow only hits like about a 140lb recurve. Apologies if you already know this, but I wouldn't want you to get to the end of a build and find you had undersized it.
It was a demonstration set up tacked on to a board to give an basic understanding of principal to the general populace, expecting or needing it to be tolerance accurate is just a silly thing for a quick video about the function of a 500 year old trigger design..... Man go do some math somewhere, you mechanically engineer minded jerk 😉
@@richardpeterson3753 If you're hunting with a short power stroke crossbow, I would definitely go with 250# or higher, and use a goat's foot lever (or maybe a belt hook) to span it. The typical minimum energy stored by a longbow or recurve bow for hunting larger game such as deer is ~50 J (the arrow is going to have lower energy than that due to efficiency losses). A 100# crossbow with typical Medieval 6" power stroke is going to store only 30 J, and have lower efficiency than a recurve due to less efficient materials (assuming a steel prod), short power stroke, and the friction of the string against the tiller.
It does look like the sear is actually providing a mechanical disadvantage, which is strange, but I don't think that necessarily prevents the system from providing a lighter trigger: in the single axle system, the trigger's nose is supporting the nut torque via compression, whereas the twin axle system's sear reverses that to tension. In both cases, the trigger supports those forces on a vertical face. As the trigger moves in an anticlockwise arc during release, that face remains tangent to the arc and so its top edge tilts away from the trigger pivot. In the single axle system, that movement is trying to rotate the nut clockwise, resisted by basically the full string tension, so gives a heavy trigger, whereas the tilt is actually away from the sear in the twin axle system, so the string tension is working with you and the only resistance is from the sliding friction between the sear and trigger, which is relatively low for polished steel surfaces.
Great videos thanks. Is it possible to add some kind of light spring to automatically reset the sear?
Also, would you recommend someone with fairly little experience trying a crossbow build?
With a return spring the nut can't freely rotate and would rattle or slam after release?
I think you mentioned in another video that these could have been spring-loaded, but weren't. Where would you put the spring if you were going to design it that way?
the problem with spring-loading the sear is that the sear would then be pushed back against the roller nut, interfering with its motion (a minor effect), and causing wear on both the sear and the nut, reducing their lifespan (a significant effect). This is especially true given the lower grade of metallurgy available, and even more so on lighter crossbows, where the nut might be made of horn or brass instead of steel.
Tod have you seen the trigger system of the Chinese crossbow?
I have to get into different trigger systems. The original Instant Legolas one piece trigger from Joerg is OK. but I feel there is room for improvement.
I noticed on the twin axle system there was a leaf spring underneath the trigger where did you get the spring from?
How big of a piece did you use?
This seems more like a step back rather than forward compared to the single axe trigger. Having to carry around a small easily lost poking stick would simply be too annoying. I guess it quickly evolves to something that ditches the poking stick?
Someone using such a hunting crossbow would likely have someone setting the bow for him. So all the hunter would care about is the feel of shooting the device, not the pita of loading it.
Used in war, the shooter would care that it had the punch needed to surpass the armor (maybe just a padded jack) of his target, more than the fact that he has to keep a small stick. Think of all the crap a flintlock shooter needs, let alone what a matchlock shooter needs to do to not blow themselves up handling powder and a burning match at the same time 😟
@@joejoelesh1197 FLs are still a big improvement though - succeeding the quite dangerous matchlock system after around 200 years of service. You're right though in the amount of stuff you needed in the field. 1) Gun itself. 2) Black powder. 3) Lead balls. 4) Padding. 5) Ramming tool. 6) Powder flask. 7) Extra flints. 8) screw driver -type device - most likely (cos most guns didn't have winged screw) ...there could be more I'm forgetting. On the pro side you weren't dependant on someone to carry 100+ arrows - you can easily carry 200 lead balls, powder and flints yourself. It's not light, but you're as mobile as when you're 2 guys carrying that heavy ass crossbow, windlass and bolts.
Even with polished metal bearing surface, the single axle system needs a very heavy trigger pull to overcome the friction at the sear contact point. For a 300 pound crossbow, we're likely going to see a trigger pull of 20-30 pounds...not very comfortable nor conducive of accuracy. For a hunting weapon, the twin axle system makes sense.
Instead of poking a rod through a hole in the stock, wouldn't it be easier to have the sear be spring loaded? That would allow it to automatically reengage the nut after firing.
I think the answer might have to do with the lower quality of the springs back then. When the roller nut is released, it then spins at a high angular velocity which in turn affects the sear with a rapid movement. The high impulse on a less quality spring would probably make it break or bend. I recognize this problem alot with my Lego crossbows.
Also, a spring-loaded seer would drag on the roller nut, interfering with its spin, and causing wear on both the sear and nut, reducing their life span significantly.
Why did they go with this design over the skane trigger design? It seems like the Skane crossbow trigger is a simpler design.
I find this trigger system inferior compared to single axle one. This one is more reliable to shoot, yes, but adding an extra step to reload it cancels its benefit. And what I've watched your other videos, twin axle trigger system eliminates goat's foot use and possibly other ways to span too.
Shit, I lost my poking-stick......has anyone seen my poking-stick?....I need a po............Oh, I'm dead!!!!!
@@tods_workshop is there any evidence of a captive reset pin? it seems like a rather logical thing to develop and not very consumptive of metal...
is it weird that i can kind of see how such a system could lead to wheel locks?
1:46 wait, something like a 800000 pound bow? who even needs ballistas anymore?
800 *to* 1000 lbs, not 800,000 lbs.
Anti-Materiel Arbalest.
Isn't 800.000 lbs a bit overkill?
the bolts for crossbows were heavier back then so you needed more draw weight.
modern arrow are so slim and light you don't need nearly as much.
+DarkShadowsX5 did you really do your physics? Less mass means more velocity but the force is equal.
Singularity of infinite wisdom you misunderstand, medieval bows were made of steel and composite and had short draw lengths, so something like 400 pounds for example would generally be effective against unarmored opponents
medieval crossbow has very short draw length so needs a lot more draw weight to match (or surpass) the energy of a bow shot
He didn't mean 800,000 lbs. He meant 800 *to* 1000 lbs.
Very interesting but the Chinese had a far better trigger system a thousand years before.
better design but overall it lacks elegance in the fact you need to manually actuate a part of the trigger system to reset it.
and losing that pin is like losing the key to your house. you're fucked.
they could have easily made it even better by putting a lever or somehting on that piece. at least then you wouldnt have a pin to loose.