best trigger design.

Many years ago,I made a crossbow.I am starting a build at the moment.I would like to know what members who build crossbows think of as the 'best 'trigger' design.I have looked at a number of builds,both on here,and on the internet.Aluminium seems to be a popular material for trigger mechanisms.I have a problem with that.How does aluminium hold up,as a sear,for example?I would think it would wear,and rapidly,even if it was toughened.
Hardened steel would seem to me to be the way to go.I am very interested in hearing from those who have built trigger mechanisms, particularly those using aluminium.

I have not used aluminium, only steel and wood. I agree sear surfaces should be steel. I suppose you could build a mechanism using aluminium and add steel at the contact points.


The best trigger is one that can hold back the string of a heavy draw weight prod yet still have a light pull so you don't have to jerk the trigger. This can be accomplished through the use of transitional levers and proper geometry. Also I believe a claw over system to be more accurate as it allows the string to slip under the claw and down on the track with less oscillation than under claw releases although these can be made to work just as well. Working on an over claw release now will post pictures soon.

Todd

I am at present contemplating a laminated trigger design,the one for the trigger mechanism that I used on the crossbow I made forty years ago,although that one was made from solid.
                                        the criteria for my crossbow is as follows.It must be cheap to manufacture,using commonly available materials,or scrap.It must be manufactured using hand tools,and the sort of power tools that an average person would have at hand.It must must as aesthetically pleasing as possible given the material restrictions.It must be as portable as possible,as it is to be a working weapon,and must have sufficient power to take down big game at ranges up to 100 metres.This is the 'inspiration' stage,so it is going to take a while,probably 5 times longer than the'perspiration' stage.I will update this thread as progress is made.

i made this animation to explain my disigen

Agree with Todd, over claw designs are the better. Prevent string jump and negate the need for deliberate string pressure on the rail

The commercially available Triggertech... http://www.triggertech.com/ is a brilliant refinement of this...(if only I could figure out how the roller is held captive, and returns to the setting position LOL)

I also like the toggle style as in the Swissbow. Tolerances and pin locations are critical, though I imagine there is no need for hardening sear points, as it really doesn't have any!

Here is trigger design i made last year where all the moving parts are made from steel. And the rest of aluminium. it has crazy low trigger pull and holds up very well!

Hey Hermit, not sure I could name a best design because there's too many aspects- best as in easiest to build, or lowest maintenance, or crispest pull, etc. Generally I agree that the over claw is the way to go, but that could just be because that's what I've been messing with lately. I've made mostly roller-nut mechs, and once I got the hang of it I've never had to fix or adjust or even check on them, built right, they're kinda bullet proof. Regarding material choice, tool steel, even unhardened in the sear faces, has it all over aluminum or just about anything else. I would, and have, use Delrin plastic before resorting to aluminum for any of the load-bearing components. Aluminum would work well for the frame or box of a drop in trigger mech, but otherwise I'd stick with steel. If you can case harden and polish the sear faces, it will last longer than you will.
Gnome

Geezer here, on the subject of 'best trigger design'.  At the risk of looking ridiculous (because I always build with simple medieval releases) I don't see any real difference between building an over-claw vs. under-claw design, so long as there's some sort of robust string-snubbing structure to prevent string hop.  It looks to me like one could achieve pretty much the same ends with either design. 
However: there's usually a lot more room INSIDE the stock for an under-claw than you'll have when building some sort of structure above the string for an over-claw.  Such a structure will almost certainly require a raised foresight, to match the necessarily elevated rear sight atop the over-claw.  Pretty soon you get into the M-16 solution of very high elevated sights front and rear.  And that's not so bad, considering you're gonna have to do something about creating a fore-sight that makes room for passing bolts.  
So in conclusion, though I don't see any necessary difference in over vs. under-claw locks, the choice of one vs. the other will probably have a big effect on your over-all design.  Does this make sense, or am I just blowing smoke again? Geezer.

PS: Which is to say, everything is connected. Any one change will result in other, unanticipated changes.  The secret of good design is to see the train coming when it's just a light shining way down the tunnel.
That's one reason I like medieval designs... they've been tested and tested and tested.  Geezer.

I'm with you Geezer.  Seems like over-claws just create superstructure to house the mechanism, where under-claws house the mechanism in the tiller.  I suppose if one is inexperienced in carving out lock mortises, bolting a superstructure on top seems easier.

I also agree with Gnome.  There really is no such thing as a "best" action -- too many variables.  All actions are adjustable to one degree or another.    IMHO the biggest distinction is between those actions with a trigger versus those with some sort of 'tickler' lever arm, and whether you want your crossbow to look like a futuristic or historic stick flipper.  But the Han Dynasty bronze action had a trigger,  long before Europeans started building crossbows.

Hey Guys,

I don´t know if mentioned at another point, (especially over-)claws do get trouble when coming to very high draw weights.
The structure of the claws and mechanism was limited in comparison to a big roller nut, which is an abstracted single axle that simply revolves away when released.

As for those of you who do build at moderate weights due to modern material benefits, this should not be very important.

The later claplock has its benefits in totally reducing the forward force to the tiller instead of a lock mechanism, so only dealing with the upward force applied by the string to get into its original direction.

Greetings Rizz