Need help understanding fly design.

[Rolf]

I made flies for three locks using the following the instruction discussed in this post.: https://americanlongrifles.org/forum/index.php?topic=76144.0
When the tip of the fly is flied this way, the full cock notch works great, but not the half cock notch. When cocking, the tip of the sear hangs up on the tip of the fly and does not go into the half cock notch. When cocking to the full cock notch, the fly moves out of the way and the sear engages the full cock notch. When tripping the sear, the fly moves forward an keeps the sear out of the half cock notch as it should.

When I file enough off the tip of the fly to get it to move out the way when cocking to the half cock notch, I get a slight bump when tripping the sear and it moves over the fly in the half cock notch. The fly works and keeps the sear out of half cock notch as it should.

Should I try to reduce the heigth of the half cock notch or is there another solution?

Best regards
Rolf

[smart dog]

Hi Rolf,
I need to see a good clear photo of your fly detent.  I wrote "fly detent" so some comedian doesn't try to post a snarky off color comment.     The tip of the fly is filed into an angle with a short side or facet and a longer side or facet. The point at the tip of the fly is off center biased toward the front of the lock.  The short facet faces forward and is abrupt enough for the sear to catch it and move it backward when the lock is pulled back to halfcock.  Then when the lock is pulled to full, the longer more gradual facet acts as a ramp so the sear rides over the half cock notch. The pointed tip should just barely stick up above the lips of the notches.

dave

[Daryl]

Thanks Dave - Thanks to your description, I know have an understanding how the fly works - before, it was a puzzle.

[Bob Roller]

It's an intercepting cam and nothing more.On a bench crafted lock the radius of the sear can be changed instead of piddling with the fly.
The half cock is found on most better locks today and the "fly".The top of the line English rifle locks like those from Brazier and Stanton
with 3 and 4 "pln" bridles.These same locks for shotguns frequently have NO fly and trigger pulls a bit heavier than that of a target rifle.
The preload on the mainspring determines the acceleration and the angle of the full cock and shape of the tip of the sear was factored into these high end locks back when they were commonly used.I have had the opportunity by owning some of the fine guns that used these locks plus the friendship of Lynton McKenzie who loaned me anything I wanted from his collection for study and copy purposes.
There is a lot more to MAKING locks that most realize and they are or can be labor intensive if the maker really cares about the eventual owner.Get it right if possible and NOBODY ever made a perfect one and I never did and can't now even if I started making them again.
This is the last thing I thought I'd be doing now and hope it helps even a little.
Bob Roller
One thing I forgot was the position of the fly's pivot point and some locks will work best with the apex of the "V"to the right of the small support shaft as on a left hand lock and the left on a right hand lock and some work with the "V" straight under the shaft.The radius at the
rear of the tumbler and the shape of the engagement area of the sear is another.

[Rolf]

Thank you smart dog and Bob for your replies. They were a big help.
I think, I've found my main mistakes. I tried to make the flies symmetrical around the axis from the tip to the tit.
Also the tip does not go above the top of the half cock notch. Did a modification on the last fly I made. I increased the slope of the front facet and now the half cock notch works a lot better, there is still a slight bump. I'm going to make and test out a few asymmetrical flies and will post pictures of the results.

Best regards
Rolf
   

[runastav]

Hi all!
Quick made fly from a old skrew(BMW) in the lathe and cut and file can harden if neded
Runar

[Bob Roller]

Where are the pictures showing my way of capturing the "fly"in the tumbler during the shaping process??
Bob Roller

[Rolf]

Where are the pictures showing my way of capturing the "fly"in the tumbler during the shaping process??
Bob Roller

Hi Bob, they are on this post.
https://americanlongrifles.org/forum/index.php?topic=76144.0

Best regards
Rolf