Updated 'Stecker' button 8/12/2001 new pin fixture #17 and #18.
'Stecker' Replication .

Completed 7/30/2001

Shown at the left are two completed Replica 'Stecker' cables. Move your mouse over the image at left to see the original M4 'Stecker'.

#1
This is a "real" 'Stecker' from David Hamer's M4 Enigma. Note the special ground screwdriver necessary to remove the top screw/nut.


Real M4 Stecker

#2
A view inside the 'Stecker' shows numbers and markings on the inner top case half. These a faithfully reproduced in the replica molds.


Real M4 Stecker

#3
Before pouring the mold, a high vacuum must be pulled to rid the mold of air bubbles/ We must get to 28.5 "Hg

Pulling a Vacuum

#4
After the vacuum pull, the mold is poured around the part. This is a very "safe" process to use on historic parts.

'Base' molds

#5
This photo shows a set of molded 'Stecker' cases. The two on the left are "real" M4 'Stecker' case housings.
Molded Stecker Parts

#6
This is a 'Stecker' comparison. The one on the left is from the M4 Enigma. The one on the right is one molded in the shop. The parts are shown "put together", each are actually made of two seperate parts. The top half, which is a two part mold, male and female. The bottom half is a one part mold.


Comparson

The parts need to be trimmed up as you can see some flashing at the bottom. It just came out of the mold. Some talcum powder remains on the part.

Once it is polished, it will shine just like the original.

#7
Consistency is the goal here. With the newly molded bucket of 'Stecker' parts (seen of the left) we setup the Mill/Lathe Combo to cut the flashing and make sure each part conforms dimensionally to the original.


Milling the 'top' face

#8
Here the lower half of the 'Stecker' trimmed to exact standards. The lower half will receive the connection pins in the "molded in" holes seen here.


Milling the base

#9
Cutting threads on the 'Stecker' spindle. These are 2mm diameter threads. Care must be taken to cut to the proper depth. The spindle starts out as a 5mm drill rod. The rod is cut down to 2.02 mm for the middle half and then the upper half (above the flange) is cut to 1.99mm for the threading process.

Cutting 2 mm Threads
#10
A set of 'Stecker' spindles is finished. We can compare the set of spindles to the actual M4 'Stecker' spindle on the lower half of the housing.
The next operation is to drill all the replica "lower halves" for a "press fit" and install the spindles by hydraulic press. This spindle holds the 'Stecker' plug together when a special capnut is installed on final assembly.

A set of Spindles

#11
Here is a 'set' of replica components made from David Hamer's M4 Enigma. Note that even the scuff marks on the original are reproduced with clarity.

A set of parts

#12
A closer look at the 'Stecker' replica. Note that the replica spindle has been pressed into the lower housing by the hydraulic press (between the brass pins).

Base with spindle pressed in
#13
Cutting slots in the pins . This allows the pin to be 'expanded' just a little to give a good connection between pin and socket.

Cutting slots in 'Stecker' pins
#14
Closeup view of the special fixture for cutting slots in the pins . Special "Jewelers saws" are required to cut the .030 mm slot width.

Cutting slots closeup .
#15
Slotted pins installed in base for a trial fit. Next step is to drill and tap the pins for the 2mm screws connection screws.

Trial fit pins in base
#16
Slotted pins installed in base end view.

Trial fit pins end view
#17
New pin fixture.

Pin shape fixture

#18
New pin fixture allows consistant shape and length. Completed 8/11/2001

Pin fixture inserted on the pin for cutting

This web page is under construction. Jim Oram, Administrator