Making the slot for a fly in a tumbler

[rich pierce]

If you did not have a milling machine, and wanted to install a fly in a tumbler that had none, would you think it could be done carefully with flat gravers/die sinking chisels and flattened up with a needle file? As cast, not hardened tumbler.

I’ve considered purchasing an alternate set of internals as the easiest solution but am intrigued with the idea of giving it a try.

[Stophel]

Some have a fly in the center of the tumbler, so a slot could be sawn in or cut in with a cutoff wheel.

[Bob Roller]

Some have a fly in the center of the tumbler, so a slot could be sawn in or cut in with a cutoff wheel.

Back when I made set triggers for rolling blocks I split the 2 notches  with a
slitting saw on a milling machine and then used pins to restrict the movement
of the fly.
On a lock tumbler I used a heavy drill press with a rotary table with x and y
capability .A stub length 3/32"3 flute end mill was used and the depth was
determined by the depth stop and a .078 shim.I made the tumbler from 1144
"stressproof"that machines like 12L14 and oil hardens like 0-1.I ran the spindle
full throttle at about 4800RPM.
I have never tried a chisel on any part of a lock and wouldn't know where to start.
Bob Roller

[Jim Kibler]

Drill your hole first, saw the edges of the inlet as much as you can at an angle, and then go at it with a small chisel.

Jim

[Clint]

Every time I start to think about cutting a tumbler for a fly, I make myself think about something else. For 'out of the box triggers, I suppose they are nessesary, but the fly introduces a certain amount of friction to the lock and they are teeny weeny and not fun to hunt down. The last lock I made had three different flies, two of which are still somewhere in the low altitude area of my shop. I began wondering about making a ring mounted fly rather than a pin mounted one. The ring type would require a spotface cutter to recess the tumbler, not a tough job. After cutting the ring recess the slot might be easier to cut , but who knows. I have a new style flint lock that I am going to trip with double set triggers, and there is no fly. The trick is to figure out the exact location of the trigger pivot and the sear pivot along with the strength of the trigger spring.

[L. Akers]

I have done it with chisels.  Drill the pivot hole first, then chisel the recess.

[smart dog]

Hi Rich,
I've done this quite a few times.  Drill the hole, the take a graver and cut the outline and a series of inner lines converging on the hole.  Take a small triangular needle file and file those lines flat like you would for a sight dove tail.  Repeat until you have the depth you need.  The critical thing it to make sure the width of the slot allows the fly to move backward enough to allow the sear to ride over it easily. engage fully in the full cock notch, and catch the fly on the forward stroke. To get that right, you have the width of the notch and the shape of the end of the fly to play with.

dave     

[D. Taylor Sapergia]

I have an old "Replica Arms" percussion rifle that was later adopted and made by Pedersoli, I think.  It has double set triggers and from time to time, the hammer would stop in the half cock notch, so I decided the tumbler needed a fly.  I annealed the tumbler, and cut the recess as Dave has described, using die sinker's chisels.  It works perfectly and has had no issues in the last forty years.

[Ian Pratt]

Hey Rich - here are a couple pictures of one I did. Castings were from a lock that had come out of a blunderbuss and the new lock was going into a rifle that I'd be making set triggers for. As mentioned already, drill the hole first, then clean the pocket out with a chisel and tidy up the floor with a file or stone. If you have a little lathe you can make a fly by turning a little "thumbtack" . Cut away most of the head to a wedge shape then fit to the notches.

[rich pierce]

Ok guys I now believe it can be done! 
Now to find out if I can do it. I have a fly collection and hope one will work straight off. Adventures in lock making. I’ve got a couple sets of castings with no holes spotted and no diagram and this is only my second or third time sorting that all out. Now adding a fly will take it to another level.

[smart dog]

Hi Rich,
A little triangular needle file with a tapered end is your friend during this task. 

dave

[rich pierce]

Got it done. Great advice.

[jerrywh]

Has anyone here ever seen the fly in a Wogdon English lock?  That is my favorite style. It is simpler to make and much stronger than any of the current production locks.

[Craig Wilcox]

You've done a great job, Rich.  Now I know to whom I send a tumbler for fly addition!

[smart dog]

Has anyone here ever seen the fly in a Wogdon English lock?  That is my favorite style. It is simpler to make and much stronger than any of the current production locks.

Hi,
Yes, he used 2 styles.  His earliest design looked like a little neck tie with the collar looped around the spindle of the tumbler and the tie being the detent.  Later he adopted the style with which we are familiar.  I have an original lock by Grice with the earlier style of fly.  It is very nicely made but I think the mortice for both the detent part and the collar might be more difficult to make than the later style.

dave

[Curtis]

You've done a great job, Rich.  Now I know to whom I send a tumbler for fly addition!

Ditto!  Nice job!

Curtis

[westbj2]

You are done n0w but i have done the job by drilling and filing away gross excess  material then using a homemade swedge w/ a  locating pin to finish,  Tumbler needs to red and likeky annealed when done,. Finiish mortise w a stone.  Expext a liittle distortion but that is easy to fix.
Jim

[Jim Kibler]

You are done n0w but i have done the job by drilling and filing away gross excess  material then using a homemade swedge w/ a  locating pin to finish,  Tumbler needs to red and likeky annealed when done,. Finiish mortise w a stone.  Expext a liittle distortion but that is easy to fix.
Jim

Jim,

That's a great idea.  Thanks for sharing.

Jim