Solid Soft Brass Escutcheon Pins Good for Peening

Fabrication

Introduction:  I came across this site while researching different types of brass.

 

My name is Edward Santoro.  I make leather bags and briefcases with solid brass hardware.  Often I need to modify or even think about fabricating some of the solid brass parts. 

 

Question:  On my briefcases, I use solid brass locks manufactured in England.  I have one method to install these locks, but am looking for another.  I would like to install these locks by peening the ends of solid brass escutcheon pins.  The problem is that not all of these pins are created the same.  Some have combinations of copper and zinc that are harder than others.

Currently, I am able to peen my stock of solid brass pins, as long as I'm working on an open area where I can easily use a ball-peen hammer and the peened end of the pin will be covered.  If the peened end will be visible, I need to achieve a more well rounded smooth dome.   

I did manage once to talk to a craftsman from Hermes and asked him how he managed to get a perfect peen on the ends of these pins.  He gave me a few of the escutcheon pins he uses.  I noticed that these pins are a brighter gold than the pins I use.  They also seem to be very resistant to tarnishing. 

 

My recent research tells me that alpha brass is a more malleable brass with less than 35% zinc.  In addition, "Prince's metal"or "Prince Rupert's metal" is a type of alpha brass containing 75% copper and 25% zinc.  This alpha brass has a bright yellowish color and has been used as imitation gold.  The brass escutcheon pins I received from the Hermes craftsman seem to fit this description.

Might anyone have additional information on this particular alpha brass and know where I might be able to get  escutcheon pins made with this particular alloy?

 

My next step might be to try to fabricate my own escutcheon pins.  I found the following melting guidelines in "Mackenzie's Five Thousand Receipts in All the Useful and Domestic Arts" (1831).

"Pinchbeck:  Put into a crucible 5 ounces of pure copper.  When it is in a state of fusion, add  1 ounce of zinc.  These metals combine, forming an alloy not unlike jeweller's gold: pour it into a mold of any shape.  This alloy is used for inferior jewelery."  Some use only half this quantity of zinc, in which proportion the alloy is more easily worked, especially in the making of jewellery" (11-12). 

 

 "Prince's metal:  Melt together 3 ounces of pure copper and 1 ounce of zinc.  Alternative:  Melt in a crucible 4 ounces of copper.  When it is fused, add 2 ounces of zinc. They will combine and form a very beautiful and useful alloy called Prince Rupert's metal" (12).

 

Thanks for any insight you can give.

 

Ed

 

 


Ries's picture

First, where do you live? It

First, where do you live?
It sounds as if you are not in the USA, as all of the nicknames for copper alloys that you use are unfamiliar to me.

(all "brass", and "bronze" are just different copper alloys- and there are literally hundreds of different ones)

There are several different systems for accurately describing copper alloys- here in the USA, we use the CDA numbering system-
http://www.copper.org/resources/properties/standard-designations/introduction.html

In europe, they generally use the CEN system-http://www.copper.org/resources/properties/standard/euronumb.html

Here in the USA, the term "alpha brass", for instance, is generally not used by any suppliers or workers of brass- its a historical term that is not much known in industry.

Having a common, agreed upon definition of the alloy and its contents really helps in the discussion...

That said- I would advise against trying to cast your own brass alloys- its tricky to maintain consistency, as the lower melting point alloys burn out, and change your final product to something different from what you started with.

It would help to find out what alloy the ones that work are, and then buy more raw round stock in that alloy. Then you can make heads on one end, cut them to length, and set them in place.

Your real problem is how to set rivets, and get a rounded head, and the answer to that is to use rivet sets. These are steel tools with rounded depressions in them that allow the end of the rivet to be formed into a nice round head. I make my own, machining them, usually using ball end mills to cut the rounded depressions. You need an "anvil" for the back, and a punch, for the top, to hammer on, and you should be able to get nice rounded backs on your peened rivets.
Many different shapes of peened backs can be achieved- round, flat, domed, cone, square, and so on- it just requires an anvil with the right shape cut in it.

A different tool is used to make the initial head on the rivets- called, oddly enough, a "rivet header". Again, most blacksmiths make their own rivet headers, especially for something soft like brass, this is a basic machining task.

When riveting, the length of the rivet is important, too- the general rule of thumb is that, to get a nice round dome, you need to allow a stickout of one and one half times the diameter of the rivet. So an 1/8" diameter rivet would be cut 3/16" long. Too long, and the end bends. Too short, and you dont get a full domed end.