Proper fitting of the fly?

[Tenn Hills Guy]

In trying to fine tune my current build project, I don't think I've properly ground the fly.  Not sure if it matters but it's a swivel breech with what is more of a back action lock.  The half cock fit seems fine, but when pulling back to full cock, I must pull 'way back' to get to push or drop the fly.  Not sure if the fly is too tight and should 'fall'...as in gravity, or, if I need some more grinding.  Using double set triggers,single phase.

[Jim Kibler]

This may be a bit difficult to explain, but I'll try.  The "point" at the end of the fly needs to be positioned such that when the fly is in it's full upward position, the point is just above the full cock notch.  As the sear rides over the fly, it snaps it forward and the sear drops into the full cock notch.   Hope this makes sense.  If not I'll try to do better with an explanation.

[D. Taylor Sapergia]

...and a fly should be very hard.  If it has been ground, it may be so sharp that it galls into the sear and cannot snap forward.  the tip of the fly needs to be polished well.

[keweenaw]

If the fly is a new casting and not hardened it will do what you're describing even if the geometry of the tip is correct.

Tom

[Tenn Hills Guy]

I have not hardened the fly at this stage.  Not sure but upon taking the fly out, I found, indeed, a little gall, tiny....but appparently just big enough to interfere.  Now the next question:  How to harden?  Temper to what color......or 'glass' hard?

[D. Taylor Sapergia]

The fly must be polished and very hard.  Heat it to a bright red and quench it in oil.  Re-polish it bright, and draw it to dark straw.  At least that's the way I have made them, and have never had one break.  Losing them is another matter.

[Tenn Hills Guy]

Polish a fly....................? I noticed when trying to hold the wee, tiny, little booger with my smallest pair of hemostats, it was cool watching it 'fly'.......no pun intended, across the room!  As soon as I can catch a flea, I will practice trying to wipe its buttocks, with tiny pieces of toilet paper.  Now, I ask myself: do I really care how well it works? What a masochist I am.............!

[D. Taylor Sapergia]

Looks is one thing, but function is entirely another.  they need to be polished, if for no other reason, so you can see the colour during the tempering process.

[Tenn Hills Guy]

Done, hardened,  and drawn, back in it's little resting place.  Oddly, or perhaps not so, it wound up looking like a squished version of the 'arrowhead' it began as.  I guess in the end, the actual fit depends on the exact geometry of the specific tumbler's safety and full cock notch.

[Acer Saccharum]

Sometimes the fly that come in a lock is too high. I like to grind them so the sear just clears the half notch. The point of that blunted arrow point you mention should be exactly under the tip of the sear nose as the cock is slowly pulled back, and pull the cock a little farther back, and the fly should pop froward, and the sear should drop right into the full cock notch.

When the fly is too long, one must pull the cock waaay back for the fly to pop forward, and then the cock has to be lowered a little for the sear to rest in the full cock notch. Another problem with a too-long fly is that it makes the sear clear the half notch by a mile, forcing the sear to press against the sear spring very heavily. This robs power from the downstroke of the cock.

When grinding the fly to fit, frequently check to make sure that you leave enough material on the back side for the sear to ride cleanly over the half cock notch on the forward movement of the cock.

I hope this makes sense.

It probably will after you ruin a few flies. 

That's how I learn.

Tom