Technical question regarding EK production: solders

[Les]

Does anyone have good, solid information on the type of solders used to join EK frames?

Previtera comments that solder "sheets" were inserted between the frames and then melted to join the two halves. Doing that would cause solder to run in an uncontrolled manner inside the frame. The outside could be cleaned up, the inside would be hidden as long as the core was in place. If you've ever seen a rusted out EK, the soldered frames don't look "messy" inside. That would suggest the solder was applied from the outside in, not from melting a "sheet" and clamping two sides together.

I haven't paid much attention to WWII crosses, but what do you folks who collects crosses from both wars know about the technological process(es) used, and the solder types? Did the materials and methods change after WWI, between the wars, and/or during WWII?

Alright, what do those with more knowledge about this subject than myself have to say?

Les

[Les]

http://gmic.co.uk/index.php?showtopic=1260...mp;#entry243605

From the archives: this thread discusses the "Gablonzer" method which was introduced circa 1942, but not universally adopted. The Gablonzer method used a shaped strip fitted into a groove on the inside of the frame, which melted and joined the pieces when heated.

Anyone able to provide information on the actual solders?

Sn-Pb (tin-lead) soldering was introduced during WWII for use for electrical circuits and some hardware joining that would be exposed to hard use and required some ability to flex. I don't think lead-based solders were used by Germans until after WWII, or haven't found anything to document that yet.

Les

[Tom Y]

A thin, narrow strip of solder melted in a carefully controlled kiln wouldn't run. This frame from an "exploded" EKI supports the theory.

Note the sharp edge at the junction of the upper and left arms.

From the traces of verdigris on some frames it was most likely a lead-copper alloy.

My period book on EK manufacture is at the bank now, but I'll try to remeber to pick it up Monday and see if it has any info

[Les]

Tom, thanks. Let me know if your book has anything on the subject.

For small scale production of gold and silver items, solders were usually made from a mix of metal filings saved from shaping the parts. Copper or another metal added would slightly reduce the melting point. The results can produce a join that's almost impossible to see. Additionally, if the melting point of the solder used is close to the melting point of the gold or silver parts, it can be enameled at high temperatures without the solder remelting and the join failing.

The larger the solder mass, the more heat it takes to melt the solder. If a solder paste is used (the paste being a mix of the solder material and flux), it can be brushed, dipped, or applied. A solder paste melts at a lower temperature than a wire/coil, or strip of solder. From what I've been reading, solder pastes can be melted on electric hotplates.

I'm wondering if mass production methods for EKs may have been something as simple as putting the core into the frame, applying solder paste, and the other half together to form a "sandwich" and then like a batch of cookies, put the proverbial sheet into an oven until the solder melted. Heat, squeeze (weights and gravity would do this nicely) and excess solder would run out. Any gaps would close through the action of weights and gravity. There isn't much complicated about this.

Making a (reflow) solder paste isn't hard to do, and applying it can be done by almost anyone and takes little skill. Cutting strips or coils, requires shaping machinery, someone to carefully place solid solder onto the part(s) to be solder, etc. Unless the reflow solder paste method, the process because it requires shaped solid solder, and someone to carefully place it, the time/man hours/slightly more skilled labor intensive.

Germany's need for manpower and resources during both wars relied on the maximum use of people, resources, money, etc. The solder paste method seems to have several advantages over shaping, cutting and placing solid solder and so on. The fact one is simpler than the other, doesn't mean it was used. Also, manufacturers were concerned about the final product and how it looked; the process could have varied from maker to maker.

Any details appreciated folks!

Les

Edited January 4, 2009 by Les

[Naxos]

Hi Les;

have a look at the link: http://gmic.co.uk/index.php?showtopic=26238&hl the pictures are from the book Tom mentioned.

Regards, Hardy

[Les]

Hardy thanks for the link to that reference. The man operating the smaller machine isn't putting the frames together. The description says he's putting the beading or edging on the edges of the blanks.

There are two "spindle presses" in the photos. If the smaller machine is putting the beading on, the larger one is probably putting the shape of the cross onto a silver blank, and the smaller one completing the process. We're looking at a two step process. Instead of one stamping to make one complete half of a frame, the frame shapes are slowly "squeezed" (embossed) into the silver. Slow steady pressure not a hammer strike!

Here's step one.

Les

Edited January 4, 2009 by Les

[Les]

Step two of the process. Using a smaller press to apply the beading by slow steady pressure (like a vise).

Interesting stuff! What the photos show is the operating machinery and methods used in a small shop. There is nothing complicated, with plenty of handwork. Later machinery would cut the "flanges" off, or punch out almost finished frames requiring less handwork that we see in the photos.

Good stuff, and the shop methods tell us how some of the smaller medal contracts were handled. We can get a pretty good idea of how some of the orders and less commonly seen medals were made in small numbers.

Les

Edited January 4, 2009 by Les