Crossbow triggers

First topic message reminder :

I often hear or read where folks are wanting to improve their crossbow trigger and in particular make the pull smoother and perhaps a bit lighter. And whilst understanding that the loads applied to a crossbow trigger when cocked, can be vastly more than those on a firearm trigger, there are some things that remain constant and are just as applicable to our needs. The following video from Brownell's wonderful website is most informative and provides much insight into how certain parts should operate together.




Pavise

I'm back

There was a topic on the Russian weapons forum Guns.ru where a guy by the nickname "sopel" had just bought a crossbow to play with while deciding on what crossbow to buy and then waiting on his Excalibur to arrive...well he couldn't sit that long so he started messing with that little crossbow without even making a single shot ... >>>Link ...

The trigger mech that was used in that crossbow is very interesting in that it's made entirely of sheet metal and that the housing is a piece of square(well maybe a bit more rectangular) steel profile/pipe like structure.

I have images of a similar model taken from a bull-pupp styled crossbow where the trigger hook is set forward a certain distance...Personally I really like this trigger despite the way it was manufactured...not perfect and can be rather tight it, but these downfalls can be slightly cushioned with a few careful alterations and of coarse - polishing.

I really need to do a better diagram that shows the principal on which the automatic safety operates in this trigger, but till then this is what I got.

---

If you go through the pages of the topic I linked to in the beginning of the post>>> this guy is on a roll and got his Excal...wooohooo...straight off starting to mess with it by first polishing the sears.



>>> All niiiicccce and smoooooth in operation of release...Yaaayyy ...only one other thing popped up

After polishing he realized that the safety doesn't function as intended. He blames the company a bit, but I think otherwise for this reason, heh...he even explains it himself >>> It was the appearance of that tiny bit of space due to polishing that caused the shift in the system that in the end caused safety to fail it's function...as the author describes > safety now causes a the crossbow to discharge as soon as the safety is taken off. ... I highly doubt that "factory made" crossbows are designed in a way that really makes them open for user modification



Anyway...he solved this problem by making a small addition from sheet metal that filled the gap and brought things back into balance.



Whatever the case was, he is a pretty lucky guy in that hew was able to bring the trigger back into operation..Thanks to him now you have this good piece of info...especially those who are thinking of going on a grinding/polishing frenzy just as this fella did.

---

Now there was one thing that I didn't notice, but my fellow crossbowman igora did...

Not sure if this was due to the modifications done to this trigger...whether it was the shift in the system after polishing of the sears or due to the scratches from sanding, but there appeared a tiny and barely visible "crack" right near the axel.



another reason why I like the version presented on Robins site over the one Excals use >>> It's just beefier in my opinion.



Now I'm going to go sleep with my hands in the bucket of ice.

Ivo,

With the utmost respect to readers.

"A little bit of knowledge can be very dangerous". I don't know who first said that, but too many folks think that all they have to do to "improve" a trigger, is simply polish the sear and bent engagement points. Wrong, wrong, wrong!!!!!!

You apparently endorse "Robin's" trigger and some might see this as "it" being more resistant to the maladies of messing about with. Not at all my friends, and if you look at the engagement points you will see that they are almost identical to those of the example in the subject story. (Before they were altered.) However it is my opinion that any "safety" block be so designed and installed as to bear directly on the bent where it drops away from the sear, and not at some more distant part where stress and possible bending of parts might negatively effect its purpose. Robin doesn't believe in "safeties" inasmuch as folks are inclined to trust them instead of always keeping the weapon pointed in safe direction and not load it until ready to shoot. In fact the word "safety" is extremely misleading and such devices must never be fully relied upon to prevent unintended release.

We crossbow builders must never forget the oft enormous loads being held back by those two tiny areas of metal and it is VITAL that the angle of engagement be maintained and NOT altered during the act of polishing etc. In fact it is better if the sear face has a slight positive interface with the bent-lip and thus tends to force more engagement rather than less and thus excite disengagement when reduced (polished) friction plays a lesser part in the design of operation. The hand-grip and index finger relationships are very important too and the proper distances for these are contributors to the "feel" of the trigger pull which can be "heavy" simply because the finger is not in the optimum position when these muscles are applied to the trigger lever.

Please not let's treat our crossbow triggers too lightly. (Pun intended.)

Pavise

No No No Good Sir!..but Yes Yes Yes at the same time!

Perhaps I really overdid it with sarcasm in my above post, but I do not i na any way advise anyone to do what this guy did. I forgot to say at the end >>> MAKE YOUR OWN TRIGGERS > YOU WILL LEARN MORE!!!.

Sear engagement angles is what our topic here began with and once again we comeback to it saying the complete opposite > while being right at the same time.

When in firearms the same set of laws applies, it is really irrelevant when crossbow action is in the spotlight. There is no firearm that I know of where a sear has to maintain hundreds of pounds. Should this much poundage be applied to the sear angled greater than 90 degrees (modified Excal trigger from above post) obviously things will slip and slide(especially if sears are polished and lubricated )...as you said "proper angles" MUST BE MAINTAINED! And I agree...In trigger from Robin's site these angles are clearly visible.

You also mentioned...

In fact it is better if the sear face has a slight positive interface
with the bent-lip and thus tends to force more engagement rather than
less

I also agree as I've been taught that this in some cases(especially with a polished and graphite lubricated action) will allow a half pressed trigger to ride back into full latch retention...perhaps a very precise operation, but this is what I would go with instead of doing the opposite.

The hand-grip and index finger relationships are very important too and
the proper distances for these are contributors to the "feel" of the
trigger pull which can be "heavy" simply because the finger is not in
the optimum position when these muscles are applied to the trigger lever.

Now this is a wicked topic Pavise...untill now I have not met a single person who would throw this into an explanation...I really hope we can continue a bit on this. All this time I had a feeling and didn't tell anyone untill testing it myself(which I want to do, but my build has halted) >>> My theory is:

A certain stock anatomy trick, whether carved in the stock from beginning or artificially created with addition of pillow like grip anatomy located tight under the trigger finger...in theory I believed that this would change the angle in which the finger engages the trigger hook....ever hear of anything like this?

PS: I really need to make some diagrams, but I'm stuck away from home typing on my cellphone ...so I'll be adding them a tad bit later this week.

Hey guys,


It's been a while since this topic's gotten some love.

So here is a bit of eye candy for you crossbow junkies.

Arbalet.info > Trigger Mechanisms 1

Arbalet.info > Trigger Mechanisms 2

...and of course a very informative topic by Mr. SAM which not only has medieval trigger mechanisms of all flavors, but also crossbow blueprints he so generously drew out and posted for the public.

Arbalet.info > Crossbows XV - XVII century

The pages are in Russian, so it isn't a directly usable resource...you can go ahead and struggle with the translation of these pages(keeping in mind that it's full of Russian idiomatic expressions and badly mistyped/misspelled words) or you can grab a picture and link to the page to discuss it here.

I'm Russian and read those topics, so it will be fun to revisit it with you guys and if you are interested in anything I will be glad to translate it for you.

Ivo

PS: There have been worries of getting viruses from these pages and the
pages they link to and I will talk more about it in this topic >>>Surfing Internet Securely

Hi Ivo, I was just looking at those pages last night! Here is something that can help our readers. Down load Google chrome, it is free and can automatically translates whole pages to English. Translation not perfect of course, but is still very readable.
Todd

5+ Todd

Got a small addition for you all.

Seen this cool little build on another weapons forum where a guy built a mini crossbow...what really caught my eye is the trigger mech. Take a look and let me know what you think...



in my opinion, while it's lacking some healthy engineering - it's still one of the coolest self built triggers I've seen.

Ivo

That is a nice but simple compound lever trigger system and a nice little bow to boot!!

Todd the archer wrote:I would like to build a crossbow with a sophisticated trigger in the future, but for now I am going to put together a more primitive design. Something along the lines of a southeast Asian style. Having said that, how do they release the string from the notch in the stock/tiller. It does not appear they use the medieval push up peg system. I have looked at various pics but is not completelty clear. maybe someone know better how their trigger works.

Todd

Robert

jopsa wrote:

https://2img.net/r/ihimizer/img142/5834/str214215um7.jpg
https://2img.net/r/ihimizer/img142/5163/str216217sy4.jpg
https://2img.net/r/ihimizer/img297/4046/str218219ux5.jpg

Robert

There is this cool show "Weapon Masters" with a creepy and hyperactive "Chad" guy (ignore him )... this episode that vid I yanked from somewhere a while ago shows the internals of that little Chu ko nu crossbow and talks a bit about their history.


By the way, that Chinese guy is Yang Fuxi. A very serious figure in the bow making world.

cmgower wrote:That is a nice but simple compound lever trigger system and a nice little bow to boot!!

I think this thing has potential! I'm looking at a way to put an auto engage safety on it and perhaps make it function like a dog-leg release system (found in archery releases and Twinbow crossbows) to get a quick release with short trigger travel.

This is a Chines copy of the HW Record trigger group for air rifles it's immensely strong, true two stage and can be adjusted safely to a very light let off. It's designed to hold the massive force of a compressed air rifle spring.

Nice thing is you can buy them!!! (Buy a Real HW one though )

May need minor mods but it should work and enhance any bow .


ATB Ora

Wow, I didn't know about that trigger mechanism. Thanks.



That looks like it could work, at the very least it looks like a good place to start experimenting.



So many possiblities

Worst case; all you would need to do is make a modified version of lever1


Ora

Yeah that could work too.

Hi ora8i,

I built a similar trigger, also based off of one designed for airguns. Looong lever...if I knew what I was doing then it could have been a good one and I wouldn't need to change the string every five shots.

The adjustments in this one are very interesting. As I understand lever 3a is basically a U shaped channel/sleeve that goes over a (solid) lever 3b and are both retained on the same axel? That's pretty damn genius.

Worst case; all you would need to do is make a modified version of lever1

I was thinking about that too. The latch in it's present form is way too rough, as I said earlier it went brutal on the string....I guess it just doesn't allow it to roll off smoothly enough, where in an air rifle it's not such a big deal when releasing the piston (perhaps even beneficial).

Adding a dedicated latch and using slightly shortened lever 1 to keep it locked would probably be good start, I'll finish sketching what I'm talking about in a bit...

All in all, pretty cool trigger.

Ivo

Why not add another lever / a release, that lever #1 could control, turning it into a 5 axle trigger? Turn the hook on lever 1 into a sear?

Turn the hook on lever 1 into a sear?

You got it.



Looks like it would work very well. However, with this composition in mind...I think modding the factory mech. might be a bit of a doozy considering that in my drawing lever 1 was shortened about 1/6 in length (and of course the axel moved). The housing is also different since I was drawing it the way I'd build it...can't help it.

Ivo

Ivo.

That's a good looking Idea but you may have gone over the top, could you put a pate each side of the existing group and pivot the string release from the outer plates? This would leave the original HW mechanism more or less untouched.

ATB Ora

True, my bad.

I did sit down last night and did exactly that, remembering the original theme of the thread which after all was aimed at using the factory trigger and not building from scratch.



Indeed, it does look good and mod friendly. And as you said, it doesn't have to be a separate housing, can be a set of plates just as easy...just my latest fascination with pressing my own housings.

I didn't have the time to play with the latch and I guess that was a good move since you can see the areas that may need to be adjusted depending on the latch design ( * I have no actual dimensions of this thing, so it really will depend on what comes in the mail )



And last thing...the original mounting holes are still in great locations. Is there anything that's NOT good about this trigger?

(Buy a Real HW one though )

Considering that most of us will likely go for the clone I think it would only be fair to chip in some info I found on it and it's drawbacks. Found this blog that has a nice comparison of the clone and the original as well as tuning info to get the Chinese boy up to par.

[ Xisico/BAM B26-2 Part 1 ]
[ Part 2 ]
[ 3 ]
[ 4 ]
[ 5 ]
[ 6 ]
[ 7 ]



Very good info and a user friendly tune. Guess now there is a question about price and availability.

From what I've seen on the net...The Rifle seems to be discontinued.

ora8i, Since you probably already did your research, any idea where one would go to grab one of these triggers? And the prices would be an interesting thing to know too?

Thanks,

Ivo

I like the design of this trigger, has some simularities to one I've seen before. What do you think?



Todd

The Chinese trigger is not as well finished and the one I had was flat between the 1st and 2nd stage bumps I fixed that by cutting a groove.
For parts in the UK I'd try www.airgunbbs.com or http://ukchineseairgunforum.myfreeforum.org/index.php

In the US.

http://www.network54.com/Forum/113813/
or
http://www.network54.com/Forum/79537/

Just register (free) and ask somebody will have one going at at a fair price


ATB Ora

Ora8i,

Thought you disappeared...but in the end it was I who disappeared instead.

Thanks for the info. I also found a few dealers myself...looks like this rifle isn't as dead as I thought and internet is full of info on it.

I've wanted to build/mod airguns myself for a long time now, but since archery was what got me into building, I started with bows and moved up to crossbows...next step >>> Tool up and get into airguns...it's only logical and quite a broad field to explore.

Todd,

Only you man.

You got quite an eye my friend...one night you might look up at the sky to do some star gazing and instead will see trigger groups. Just messin. Still, good eye for detail...Todd is in the Zone.

Ivo

Im new to this i built a crossbow when i was very young and it didnt pack much of a punch. im trying to make a better one. im have a problem trying to figure out what spring to use and how to place it in order for the trigger mechanism to not slip under the pressure of the bow string and also so the trigger isnt to hard to squeeze.

Hey I recognize that last post by Ivo, hehe. That little baby is called Persephone and it's the first legit crossbow I ever built.

She's been upgraded a bit since that video, with a bolt holder down tongue thing, an arrow grove and even a bottle opener on the bottom (not pictured).



to this...



Still got the original trigger, great for shooting pencils or anything that size and shape a long ways.

Yeh, I just couldn't resist putting up your mech. It's really something...I was trying to give it a name...bullpup medieval/tickler sort of sounds like Joerg's *slingshot crossbow*, so I thought I'd just leave it to the author or time.

*animation*

You've got to teach me how to do that man. That's Flash right? ...I've been trying to animate things with Sketchup - hating it.

Ivo

Here's a pic of a new trigger mech I knocked out after doing some homework around this site


Components are made out of 8mm mild steel and claw fingers are made out of 2 strips of 6mm welded to an 8mm centre sear section. Cover plates are made from 1.6 mm zincalume coated plate. Pivot and stop pins are 6mm round bar welded to the backing plate. I have hardened and tempered the sear points as you can see from the metal discoloration. In hindsight I should have warmed the oil used for quenching prior to the process as I think they may have cooled a little too quick.

I may change that spring set up as I have some torsion springs on order. I might remove that tension spring and put a torsion type under the transition lever sear point. All depends on when they arrive.

I have tested the set up by placing the whole assembly in a vise and sticking a length of 10mm round bar through the claw and pulling as hard as I could. It feels very solid. The prod it's going to be flexing is an alchem 150 pounder.

Any comments, suggestions or criticism is most welcome,as it is one thing to read all you can on these crucial little parts to a crossbow, but quite another to produce one to an acceptable level.