Siler Lock building help needed

[Mississippi Mike]

Hello everyone.
I'm new here but not to the hobby.
This is my first attempt at building a lock. This is a small Siler lock and I am having a few problems. This is an older kit I got from a friend. I don't know if that is part of my problem BUT..... anyway here is my issue:

After assembling the lock I cocked it a few times to see how it felt. It seems to have an issue with PASSING by the half cock notch. If I go really slow and try to stop the hammer at half cock it will do so and will function properly there (It will not fire). Then when I go to full cock the lock functions as it should.
If I examine the lock as it goes through the cocking process it seems the main spring may be too long. The tail of the main spring seems to be forced into the corner of the tumbler which would seem to make a difficult transition as it continues to ride on up the face of the tumbler.

This is the only Siler lock I have so I can't compare it another Siler I have on hand.

What do you guys see in the cocking of the lock stages below:



At Half cock:



At Full cock:



What do you think......
Is the spring tail too long?
Does it need to be bent so it will stay out of the crotch of the tumbler?
Do I need to try another spring?

HELP......

Thanks everyone for looking!

[D. Taylor Sapergia]

It appears to me as though the hole for the mainspring pin was drilled about 1/16" too far to the rear.  The tip of the mainspring should bear against the tip of the tumbler.
Regarding the cocking issue, the sear spring must have enough tension to snap the sear nose into the notches of the tumbler.  It's really tough to diagnose without having it in hand.  The length of the fly, and the hardness of the parts too makes a big difference.  For example, if the fly is galling into the sear as the lock is cycled through the half cock position, it will prevent the sear from engaging the notch. 

[mjm46@bellsouth.net]

It looks like you might be able to remove a little of the tip of the mainspring and also a little of the tip of the tumbler. But I suspect your problem may be with the tumbler sear relationship. Take the mainspring off and the bridal, restrain the sear with the screw only, leave the sear spring in position and cycle the lock gently to see if the sear actualy engages the half cock notch. Could be the top edge of the sear and the bottom of the tumbler are binding a little. Just a guess.

[Mississippi Mike]

Thanks for those pointers.

The hole in the lock plate for the mainspring was pre-located in the casting. So that is how I got the location for that hole.

I could weld up the hole and re-drill it more to the front of the plate I guess.
I thought I might try to either bend the end of the spring a bit or either cut some out of the corner of the tumbler first.

The sear seems to engage the tumbler correctly as I slowly cycle the lock.

[Dr. Tim-Boone]

I agree with Taylor, and, depending on how old this small Siler lock is ............you may have the old tumbler which had several small problems. Chambers has a new tumbler that makes the lock function much better.  I would suggest that you send the lock to Jim and let him fix it for you unless you have all the machine tools etc needed and the ability to properly harden etc.   Since you say this is the first one you have done I would at least get Jim to look it over to determine if it something you can fix or if more is needed.  Perhaps he will comment here.  Great pictures!

[Mississippi Mike]

Thanks for the reply Dr. Tim.

You are correct.... this is an EARLY small Siler lock kit.
This lock kit was a gift so no cost thus far. I inquired in a couple of places on the issue of having the kit assembled for me but the one that DID give me a price was prohibitive. I could buy 2 already assembled locks for the price.
Anyway... this will be an attempt by me to make this lock work. I can harden the parts since I have experience with that.
My main issue right now seems to be the geometry of the lock.

I might not have explained this issue with the lock well enough to let everyone understand. I seem to miss the half cock notch because as I start to cock the lock it starts to bind. I put more pressure on the hammer and when it gives I am putting enough pressure on the hammer that it just passes right by the half cock notch. IF I can go really slow and carefully try to make the lock stop at half cock I can do so. It engages well and will stay in the notch.

My issue seems to be the relationship of the mainspring with the tumbler.

[rich pierce]

I'd just get the spring red hot, bend the hook some more, re-harden and re-temper it.

[Mississippi Mike]

I'd just get the spring red hot, bend the hook some more, re-harden and re-temper it.

That is the way I am leaning.

I want to give this a try myself....... I know I am not an expert on lock tuning but I sure would get a lot of satisfaction if I can make this lock work on the pistol I am building!

 

[smylee grouch]

Would stoning the tip of the main spring help any? You wouldnt take much off and it wouldnt cost anything to try. Just thinking out loud here.  

[Mississippi Mike]

Would stoning the tip of the main spring help any? You wouldnt take much off and it wouldnt cost anything to try. Just thinking out loud here.  

Maybe so...... I think I am going to try to slick up the parts first to see if there is any effect.
The tumbler is clean but the spring is still rough.

[Mississippi Mike]

I saw this picture of a Small Siler lock upgrade kit at Track.
I see there is an "inset" area in the tumbler where I seem to be having my "bind-up" trouble.



Maybe if I take a round file to this area of my tumbler AND a polish job on the spring hook........

I think I need to keep the spring hook from having to "climb" the second face of the tumbler in that corner.



 

[JTR]

I think I need to keep the spring hook from having to "climb" the second face of the tumbler in that corner.
 

Exactly! Fix that and you've fixed your problem.
John

[wmaser]

Grinding the tip of the mainspring down should fix it. I would try that before bending and rehardening anything.

[rich pierce]

Good advice; at the same time keep in mind that if by grinding/stoning,  the contact patch at the foot of the mainspring becomes substantially smaller, it may wear both surfaces more.

[Mississippi Mike]

That did it!
I filed and slicked up the area of the tumbler that had such a "sharp" corner and made the corner more rounded on the inside.
This gave the spring more room to approach the corner without binding.
It cocks nicely and goes to half cock easily.



Thanks for being a sounding board and helping get this problem worked out!

My Best to all

Mike

[Dave B]

You must deal with the fact that the spring must rest at the end of the tumbler.  The cock needs the force from the main spring  to be at a maximum point of leverage for good impact at the frizzen when fired. Your bending the tip of the spring would help improve this but the reality is you must move the spring back to the better position. When drilling the drill must have walked  out of position a little. Here is what that spring tumbler is supposed to look like on a small Siler. forgive me for it not being a flinter but the point is the same regardless. If you just bend the tip of the spring you will not get any little or no cam effect as result of the spring moving the distance from tip to the point closer to the tumbler axis. It may even cause the spring to hit the upper bolster preventing the tumbler from rotating enough to allow for full cock engagement.

 

[Jim Chambers]

On the locks we assemble here in the shop, sometimes we find the exact thing happening.  Sometimes when drilling holes in the plates the drill can wander one way or another by a few thousandts, and that is all it takes to change the relationship of one part to another.  It is most critical with the relationship of the mainspring to the tumbler.  When I find a lock that works like you described and wants to fly directly back to full cock, I simply remove the mainspring, touch the tip (the part that engages the tumbler) to a scotch bright wheel, and polish off just a couple thousandts of the tip.  That's usually all it takes to eliminate the problem.  That should give the lock that "compound bow" feel where the greatest force is at the bottom of the stroke, and the amount of cocking force reduces as you go from half cock to full cock.  Glad to hear you resolved the problem with the excellent advice you received here on the ALR.

[LynnC]

Have you got it opening the frizzen with enough power to make sparks?

If not, D Taylor made a good observation.  Moving the spring forward to correct the problem is EZ.

Take out the main spring, countersink both sides of the hole slightly, drive in a short piece of steel (file a nail) with a little sticking out both sides of the plate and peen it to fill the countersinks.  File smooth, center punch and re-drill.  It has worked for me when I've screwed up 

[smylee grouch]

When I look at your photos it looks as the mainspring isnt bearing far enough down on the tumbler and if it isnt it wont have as much of the cam effect advantage Jim talked about.

[Mississippi Mike]

Thanks for your comment Dave. I see your point by pointing out that the spring needs to be closer to the end of the tumbler arm in order to create enough force and SPEED in order for the flint to create enough sparks to reliably ignite the pan powder. My wooden "flint" does open the pan reliably but the real test will be with a real flint in the hammer jaws.

Also, thanks for chiming in Jim. I intend to go ahead and harden my parts then see how well the lock works with the geometry I have at the moment. I may move the main spring forward a bit after seeing Dave's comment. We shall see.

After this exchange of comments I have a much better understanding of the internal working of a lock.

This is truly a great forum and a great bunch of knowledgeable people!

Thanks EVERYONE!!!!

Mike

[Mississippi Mike]

Have you got it opening the frizzen with enough power to make sparks?

If not, D Taylor made a good observation.  Moving the spring forward to correct the problem is EZ.

Take out the main spring, countersink both sides of the hole slightly, drive in a short piece of steel (file a nail) with a little sticking out both sides of the plate and peen it to fill the countersinks.  File smooth, center punch and re-drill.  It has worked for me when I've screwed up 

Good idea...... Thanks!!
(Much better than welding the hole and starting over (LOL).