Interesting hammer screw

[westbj2]

The lock shown in the pictures is from a c.1720-40 unmarked Dutch pistol.  It is in need of a new sear and tumbler.  When I started dis-assembly, it took a bit of time to figure out how to remove the slotless hammer screw.  lock design includes no bridal so the decorated screw is on a shaft which is secured on the back side of the tumber by the square nut.
Jim







 

[mountainman70]

Man,whatta noggin scratcher!!!At first look,face appears to be ol Kilroy,do you think?Good luck on thisn,I have a perc old lock that trig screw is actually a shaped nut,that has slots on each side of threaded center.You just never can tell what these old guns will teach us.Good luck!Dave

[Ryan McNabb]

Hollow out a brass rod basically the shape of the exterior dome and epoxy it to the dome.  This might give you adequate purchase to remove the nut.  Maybe dimple the curved interior surface of the rod end for grip on the epoxy.  Then heat gently to remove the rod and epoxy.

Beautiful engraving job.  Notice the plate looks like its a half inch thick thanks to the engraving, but you see it on edge and it's paper thin.

[Bill Paton]

This looks like the very old system used on snaphaunces and very early flintlocks in which the shaft is forged integral with the cock. The shaft  then passes through to the inside of the lock plate where it is squared INSIDE the plate and the tumbler (with a square hole) is fitted over the square shaft and secured by a pin or nut. No bridal was used in those locks. Might the grotesque mask be integral with the cock (or possibly forge welded to it) and not a screw at all? It would be a shame to bugger up that fine chiseling trying unnecessarily to take down a forge weld!  Bill Paton

[SteveMKentucky]

Hard to tell from the pictures but it almost appears that the square piece on the inside of the lock may be essentially a nut and the shaft appears to have a flat side that engages with the tumbler.  Have you tried restraining the tumbler then unscrewing the square piece (nut)?

[westbj2]

Steve,
You are correct in how the screw works.  I was not clear in my initial post but I did figure out that the square was a nut to secure the shaft.  Once the nut came off, just a tap with a punch drove out the screw.

Incidentally, it should be possible to incorporate this type of screw into a lock with a bridal.  The retaining nut inside would need to be more refined and probably with spanner slots.   With care, close tolerances and a left hand thread, I think you could end up with a tumbler that just has an over size axle on the outside.

Jim

[Acer Saccharum]

Why does the tumbler have the deep file marks on its face? There is no bridle to hide the cuts. Are they decorative, are they lock numbering system marks?

A friend pointed out that the spring and sear screw holes are blind, they do not go thru the lock face. Tricky business, tapping blind holes with high carbon technology.

A very impressive lock, by the way. Thank you very much for showing.

[westbj2]

Tom,
Yes, this is a pretty neat lock having many refinements.  In addition to the blind holes it has a ridge-fitted pan and frizzen as well as an elaborate filing detail on the end of the frizzen toe.
I can only guess that the file slashes are/were decorative.  Much of the tumbler adjacent to the notches fell victim to some rather crude work at some time.
Jim

[Acer Saccharum]

Jim, I've never heard of a 'ridge-fitted frizzen', but do I see a ridge on the underside of the frizzen. this fits a groove in the pan?  What purpose do you think this serves?

[westbj2]

Tom,
Below are pics of the pan and frizzen.  Suspect the idea was to concentrate the powder while using the style pan in vogue at the time.
Some pictures of the mounts are shown also....butt cap, trigger guard and entry pipe.

[Acer Saccharum]

Oh, yummy, thanks for the pictures!

Tom

[smart dog]

Hi WestBj2,
Are you sure that lock was made during 1720-40?  My guess would be 1670-1690.  The tumbler arrangement was common on Dutch locks of that period and even earlier.

dave

[Captchee]

 Im thinking the  ridge on the pan , with the fitted  frizzen would be more of an attempt at water proofing , would it not ?

[Ryan McNabb]

Probably so, although water coming down the side of the barrel onto the touch hole and into the pan will soon take care of your priming, no matter how many ridges you have around the pan.

[Acer Saccharum]

Keyword is 'attempted'

There were many attempts at waterproofing. Gutters, shaping of pan, etc. none of them really work.