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

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.

Looks good, the challenge with building a trigger to me has been making it with an EASY and SHORT trigger pull. The two qualities seem to work against each other.



Also how do you plan to fasten the trigger box unit in the stock? Keep in mind it has to be strong and rigid enough to resist the strain of the cocked prod.



All in all I like the design.



Todd

Hey Todd thanks for the positive. I am a fan of your recent Elk ridge and brass creation so it's nice to hear I am on the right track from an experienced crossbowyer.

I plan to drill and tap 6 x 5mm holes in the trigger housing ( 3 either side near the existing tapped holes for the cover plate) to mount to the stock. These will be reinforced with some aluminium side plates to spread the load away from the timber directly. I think this should be enough for the 150 pounder. If it isn't happy with that set up I will simply drill and weld in some 6 or 8mm nuts to the inside of the housing and bolt the SHIT out of it.

You are right about the trigger pull trade off, length vs weight. I think to achieve both in a compact set up you need to go a second transition lever. The pull in this one is perhaps a little longer than I would have liked but better too long than too short right? I'm happy to accept a longer trigger pull over a higher pull weight.

Hey there,

Nice looking mech.

If you want a shorter trigger pull, you might consider shortening the travel of the lever. This can be achieved my making a shorter sear lip.



This will make a more crisp trigger, but will also demand more care during fabrication and better materials since you want this little sear to hold an edge.

Another thing that is worth mentioning about sears - it's important to make the
sears of matching hardness. You don't want the sear wearing out against a
harder nut and vise versa.

Mounting the trigger...two screws on each side will hold the trigger pretty well, careful inletting is also a plus. Welding/bolting a piece of angle iron to the rear of the housing to counter the torque brought onto the assembly is another good idea.




Sorry, I'm kind of short on time and raving through this, hope I make at least a bit of sense here.

Ivo



Last question, is this a project topic you are planning on continuing, or should I merge this one with the "triggers topic" and you will make a new one that's dedicated to the entire project?

Hey Ivo thanks for the tips.

I hadn't considered inletting and dropping a rear mount on the assembly,but this is clearly the right way to directly oppose the forces from a cocked bow.

I am in the process of roughing out the stock at the moment so once this is complete I will determine the best way to go about a rear mount set up.

If I had access to a milling or shaping machine I would certainly reduce the length of the sear faces. As they are hand cut and filed , they are not as precise as machined components and a little piece of mind is a small price to pay for a longer trigger pull. Having said that, after I have assembled the crossbow for test firing I may do some further tweaking of the trigger.

Ivo, feel free to move this post how you see fit. I will create a new topic for the overall build as it starts to take shape so this is probably better off in the trigger section.

Once again thanks for the advice, it is great to know we are not alone in our endeavors , even if the tips come from the other side of the world! A truly great guild.

Hey guys,

Man I love it when Ivan leaves open files on my computer.

Not sure whether it was intentional or not. It looks liek he was making a 3d model of it, but anyway...

Check this thing out.





Patent >

Lo0oks Dreamy ... what do you guys think?

Antho

Haha...yeh I fell asleep sketching it out and then jumped up in the morning - late for work. So everything up on the screen was kinda classified material until you showed up.

Just messing, I was sketching it out to see how it works and if I like it... !Bang! - it's on the forum. But it's cool of you to bring it up, perhaps we can break it down and discuss the pro/cons of this trig.

The Patent is quite fresh, just the end of 2011. Definitely aimed at a railless crossbow which is really cool and is a dog leg type of trigger which suggests a nice easy trigger pull even while holding some serious weight...but here's the twist.

The motion that breaks the knee allowing the jaws to open is provided by a spring loaded bar that is also used to reset the lock. The chain links when extended can support alot of weight, but it only takes a small push to get them to fold - allowing to drop the load instantly...kinda like an extended leg supporting the weight of the body, but a little push in the back of the knee and you drop on your ass. ...same with this trigger, maybe I'll do a little animated gif later on this week and edit the message.

Ivo

I don't have a photo yet. Any way I built a xbow with a side release trigger. The arrow nock enters the string offset to the right slightly. I used a straight type of block release, (finger shaped) not the normal roller nut design. It seems to work just fine and shoot straight. What you guys think...??

Of course being new to crossbows and filled with fascination and questions of all aspects there in will set myself up for embarassment during this quest of knowledge. About triggers........very fascinating ..... simple seems best, however, cumplications of tensions and leverage and contact points and pressures seem to complcate things in pesuit of a better mouse trap all wrapped up in the idea of improvement. So far I have come to the great understanding that one should not mess with another's design without due respect, deliberation,and consideration as to the effects any alterations(including trying to fine polish contact points) And when you change one little thing you have to understand what that changes in the rest of the mechanism! All this caught up in safety and advantage.

The big thing at the momment is that I have noticed trigger positioning in relation to string release (or nut) is different in different style crossbows most cases the trigger is either forward or behind. What are the advantages and disadvantages? Is this just a design prefference? Or part of the natural evolution of things concernning the great experiment? Chaz

Chaz,

Are you interested in historical bows, or modern ones?

If the former, I would be delighted to answer specific questions to the best of my ability.

Mac

Well for instance is the positioning of the trigger in relation to the release, could that maybe an ergonomic thing bringing into consideration the design of the stock and it's relation to all components and how that is held for different applications? Example different for the hunting x-bow vs. target competition x-bow vs. military all vs. historical vs. modern?

I love 'em all ! But currently leaning toward the modern day target competition x-bow. Seeings how I have not yet built anything at this time more of a research and development mission for ideas so I know which direction to take when I feel comfortable enough to make sawdust and sparks fly.

My experience tells me that for a while talk and a scratch pad are cheap compared to materials.

Any tips, hints or practicle knowledge is appreciated. Of course when I built my wife's grand father clock I took ideas from several different plans then about eight years later wala she had one,,,,,you know anyone can go out and buy something but to put your own hand to it.....wow.

thanks Chaz

ps Now I got more days behind me than in front of me.