[Harp-L] Re: Embossing v Burnishing

[Joe and Cass Leone <leone@xxxxxxxx>]

On Jan 2, 2009, at 1:08 PM, Aongus MacCana wrote:

> Hey I see from Stephen Schneider's mail that there is more to this  
> embossing
> lark than I thought.

In the act of embossing, you are forcing material UP by putting  
pressure on the surrounding material. This causes a, for lack of a  
better phrase than I can come up with, a 'volcano' or a 'rift' effect  
whereas the material is forced up at the expense of the surrounding  
material. If one were embossing a reed plate, they would be making  
the reed plate thinner while at the same time making a thicker area/ 
portion/structure/design, (add your own semantics).

Two tectonic plates working against each other are an example of  
embossing. Mountains are an example of embossing.

In the act of indenting..in other words creating an area that is INto  
the material, you are leaving the reed plate at it's original  
thickness but pushing a design IN. One can also acquire the required  
result of INdenting, by means of ENgraving. In that case, you are  
removing material, (with little effect on the surroundings)

Soo, when a person draws a sharp object along the sides of an opening  
making a furrow or cut, it would seem that they are embossing. In  
actuality, they are swaging.

> In my simple mind I thought the object of the exercise was simply  
> to spread
> the material of the reed plate to reduce the "daylight" between  
> reed and
> reed plate. Stephen's reference to forming a ridge suggests that  
> there is
> more to the process than that.

In the act of swaging, you are working the material cold. You are  
forcing the material to go one way by use of pressure. If one were to  
squeeze the brass in a reed plate (for example) so that it flows,  
this pressure could conceivably close up the tolerances in any hole  
in the material. What you are doing is applying pressure evenly and  
consistently in a given area and making the reed plate thinner in  
that area with the idea of using the 'scavenged' metal to do your  
bidding.
Drawing a coin, ball bearing, shot glass across a slot will (cold)  
swage the sides of such slot and metal will be forced sideways. This  
will close up the slots size an infinitessimal amount. Infinitessimal  
is all that you need when working with thousandths.

In the act of forging, you are working the metal hot.

Burnishing is not even remotely related to these other subjects and  
won't be delved into.

> I have to admit that swaging like "drawing under the hammer" is a  
> technique
> beloved of blacksmiths, but don't lets knock the blacksmiths. In my  
> happy
> days as a post grad apprentice in the national railway works the  
> blacksmiths
> used to refer to  the tool room machinists and other lesser orders  
> as mere
> "blacksmith's finishers"

Which is a silly thing for blacksmith's to say. They do the forging  
and swaging. It is the rough work. Machinists, grinders, engravers,  
and burnishers do the finish work. 150 years ago, some mighty fine  
work was done in France. It wasn't done by blacksmiths. They supplied  
the roughings. Pennsylvania long rifles (often times called Kentucky  
rifles), were not made by blacksmiths. Same deal.

smokey-joe



> Beannachtai
> Aongus Mac Cana