lock polishing

[Michael]

I have a set of lock castings I purchased from Jack Brooks. The lock is copied from a German lock engraved Rubisoh under where the upper leaf of the frizzen spring is. The lock has some nice Baroque detail standing in low relief on the lock plate, cock and frizzen. What is the beat way to clean up these castings with out damaging the detail?

I also have a set of brass mounts I got from Ron Scott that were from one of his Jaeger class projects. These are highly chiseled and detailed and will require cleaning up as well. I got a nice piece of English Walnut from Wayne Dunlap and I am going to set up a light German fowling piece.

Michael

[Acer Saccharum]

I have some of those castings; I have not attempted to build the lock yet. I think Jerry Huddleston recently used one of the chiseled locks from Jack Brooks or Ron Scott.

My suspicion is that if you want it to look as a new made lock, freshly chiseled, you will have to go over every stinkin little detail with rifflers, chisels and burnishers. You may need to do a little welding here and there for pits or missing detail.

On the other hand, if you are happy with the 'antiqued' look, you may get w=away with some cleanup,  and then browning or rusting, with a final pumice treatment to brighten the high spots.

I have also considered filing or grinding off all the relief chiseling because I like the form of the lock as an import lock for an early American piece.

Tom

[Jim Kibler]

Small stones sold by Congress or Geiswen will help out a bunch.  I bought a sampler pack of their 1/8" stones so I could experiement with different grits, hardnesses etc. 

[smart dog]

Hi Michael,
Jim's suggestion is a good one.  Gesswein and other suppliers offer small stones that are used with oil to polish metal.  They have some that are the size and shape of pencil points and are very useful for polishing detail and chiselled designs.  Three-M bristle disks (also called bristle burrs) mounted in a Dremel or Foredom tool can be useful.  However, only use grits greater than 400 or you risk rounded off detail.  My usual procedure is to use stones and oil to begin the polishing, next I switch to hardwood sticks shaped like pencils and dipped in oil and pumice, rottenstone, or aluminum oxide powder.  Depending on results after the polishing powder, I may finish with a light polish using bristle burrs of the finest grits (pink and tan colored disks).  Finally, gravers, especially small flats and squares are very useful for cleaning up cast designs. They can cut to sharpen detail, or they can be used for scraping the metal surface.  The most important thing, however, is to take your time.  You cannot do this in a hurry.  While polishing away think of the poor schmucks in the 18th century who made livings polishing locks for a few pence a day.

dave

[Acer Saccharum]

The early locks were wrought iron, and soft enough to cut with a knife. The designs had to be chiseled from the solid, then filed, scraped, and burnished.

Our modern cast steels are very tough, and difficult to work. It takes a lot of time to work the castings into a clean example. I just had a though; it might be worth annealing the parts completely before trying to file them. I have noticed a significant skin on some castings which files easier once you get through it.

For pits or holes, one can inlay a piece of steel.

[Acer Saccharum]

Some of the relief work can be shaped/formed by punching with polished punches of different shapes. This punching action moves the material, and polishes it at the same time.

[Jim Kibler]

One more bit to add is that some relief work was formed from using forging dies. 

[Jim Kibler]

I feel certain stones were used to a great degree in finishing relief work.  In the 17th century examples I've had a chance to closely study, I've not seen any evidence of scraper marks or ripples from burnishing etc.   I really have been suprised how well the metal relief work is finished. 

[Acer Saccharum]

I am always impressed with early metal work, jewelry, gold work, etc. We think we are so sophisticated these days, but in some ways, as technicians and artisans, we have forgotten more than we know.

[flintriflesmith]

The early locks were wrought iron, and soft enough to cut with a knife. ...

In my experience real wrought iron is not nearly as soft as popular myth would make you believe. It engraves and files very much like mild steel. (It is a bit worse at "loading up" a file.)

Gary

[Michael]

Thanks for all the ideas. Looks like the stones are the way to go on the lock pieces. I'm not looking for a high polish, just want to take away the investment cast look. The castings are fairly soft so I don't think that annealing is going to accomplish much. For the brass mounts I'll try small scrapers and some fine riffler files.

[rick landes]

I find these little diamond file/hones work great for what your after. These seems tough and fairly cheap. The coarser grits tend to wear toward a finer grit as they are used. Makes for a longer use IMHO.

I have used them as a small backing piece for emery too.

http://www.woodcraft.com/Product/2005910/18131/DiaSharp-25-Diamond-Offset-MiniHone-Kit.aspx

[keweenaw]

Look at those castings closely before you start.  Two plates I've handled of that lock were pretty far from flat and on both of them the top of the pan wasn't at right angles to the side of the plate - kinda drooped on the outside front corner which makes a tight fit of the frizzen a considerable challenge.  The tumbler is unusual in that the fly was in the center of the notches which is really hard to install and if you put the fly on the outside, cleaning up the notches is difficult without having the cock with an unattractive position at half and full cock.

Tom

[Jim Kibler]

Look at those castings closely before you start.  Two plates I've handled of that lock were pretty far from flat and on both of them the top of the pan wasn't at right angles to the side of the plate - kinda drooped on the outside front corner which makes a tight fit of the frizzen a considerable challenge.  The tumbler is unusual in that the fly was in the center of the notches which is really hard to install and if you put the fly on the outside, cleaning up the notches is difficult without having the cock with an unattractive position at half and full cock.

Tom

Examples of why working from castings pulled directly from finished locks is far from ideal.  I've bought a few lock set castings produced in this manner and just by looking at them I could see there would be some substantial problems to overcome.  Starting from forgings or machining out of the solid is far superior, but also a whole bunch more work.