Fly problem

[Jerry V Lape]

I am having trouble with a new lock which has the fly on the back side of the tumbler.  I can't tell exactly what is going on but when going from half to full cock the fly regularly seems to interfere with the sear clicking into the full notch.  I did discover a very small burr on the fly and carefully stoned it off which helped some along with another minor burr on the edge of the sear at the edge of the cutout for the fly.  But the fly appears to get hung up on the sear and follow it up to the full cock notch, interfering with the sear settling into the full position.  Any recommendations would be appreciated.  I am not competent to start tinkering with sear geometry so I have pretty much reached my limits.

[smylee grouch]

What kind of lock is it? Maybe it could be sent back for the makers fix.

[smallpatch]

Jerry,

Are you sure it's installed the right direction?

[jlynn]

sir see if the tip of the tumbler is hitting the bottom of the mainspring.  had the exact problem this week and that was it.  filed the tip a bit and it was solved. blacken underside of spring if you need to.  mine was leaving a shiny scratch on spring. mine is round face queen anne may not be the problem but worth a look

[Acer Saccharum]

Two kinds of flies out there.

one is a flat plate with a hole in it. It can be put in backwards.

other kind is a little 'L' shaped piece and cannot be put in backwards.

[Acer Saccharum]

If your sear is installed correctly (see above post) the fly might be too long.

you need to look at how high the fly lifts the sear off the half cock boss as the cock is slowly lowered. This is easiest if the mainspring has been removed. If you can see a lot of space between sear nose and tumbler, then the fly can be ground off a little. This will help the sear drop into full cock sooner.

If you take too much off the fly, it will not lift the sear nose pat the half cock position. So take a little off, and try it.

[Robby]

I agree with Acer, first check to see that the fly is installed correctly. Once the nose of the sear slides past the apex of the fly it should spit it forward, if it is backward I don't think it can pass the tip of the fly.
Robby

[Jerry V Lape]

The fly on this lock can only be installed one way.  I compared the fly to the Small Siler fly and find they are different.  The end of the Siler's fly is rounded top and bottom.  But this fly is flat on the top and rounded on the bottom only.  I have emailed the maker to see if he can advise me a bit and I will check on whether this geometry is correct.  The sear on the Siler cams over the end pushing down on the fly once past the half way point of the fly.  That doesn't happen as reliably with the flat topped fly as the sear never seems to get on top of it.  I am beginning to suspect the fly needs reshaped to act more like the Siler fly.  I will check on the clearance between sear and tumbler as Acer suggests too.  May try the Siler fly in it.  The two locks are virtually identical aside from the fly being on the plate side of the tumber in this lock whereas the Siler fly is on the bridle side.