Modern alternative for Bakelite and what is this stippeled metal

bmklawt · Nov 27, 2020

I'm working on building a replica of the German Enigma Machine and I'm looking for something that resemble Bakelite, preferable something that can be poured into a mold it needs to resist heat as well and Bakelite so I can solder brass contacts that pressed or molded into it more more importantly it needs to look like Bakelite, I've looked into Garolite but the paper or fabric that's embedded in it shows through when machined.
Also the stippling in the part in the attached image where would I find metal sheet like that? why is it there.
Attached is a picture of a Enigma Rotor with the brass pins in the Bakelite and on the thumb wheel as well and the stippled metal ring.

Your help is greatly appreciated

dstig · Nov 27, 2020

Bakelite still exists, but is more generically called Phenolic plastic. You can get that from McMaster or many other places.

Bill D · Nov 27, 2020

IS there such a thing as flat knurling? Maybe through two rollers one flat, one shaped. like a pasta machine.
Bill D.

How to Face Knurl with a Fly Cutter - YouTube

Milland · Nov 27, 2020

You can also look into dyeing a castable epoxy, I'm willing bet this isn't too hard to do, and may be more robust than a phenolic.

On the stippling, it's likely embossed as with a die, like a coin would be. It's there to ensure good electrical contact in use, by wiping away oxides as it's rotated, and leaving a small surface area to make contact, increasing the Hertzian forces.

Winterfalke · Nov 28, 2020

From what I've been told, that 'stippling' is made by pressing it with an array of diamond shaped points, and is done to make a sheet flat. I don't know the specifics, I've heard it mentioned a few times in horology.

gustafson · Nov 28, 2020

I would think paper phenolic, Garolite XX from mcmaster, is the closest thing to what we call bakelite if you are going to machine from solid

surplusjohn · Nov 28, 2020

Fyi. In case you come across some old thermoset. Much of it had adbestos filler in it.
When i was a teen ager, my father ran a compression molding plant. They brought in abestos in dump trucks and dumped it in piles. Then mixed it with all kinds of other fillers and reinforcements plus the powdered resin. Then molases to make it into a dough. Then the dough was pre weighed and sometimes pre heated then placed by hand into vertical presses.
This was a very old plant and the presses used water from a central pump instead of oil. The water was once through and ran out of the press into a gutter and then out the back of the plant over a clift into the canal.

specfab · Nov 28, 2020

RE: the phenolic material -- As was previously noted, paper-based material will be the most uniform in appearance after machining, and a good-quality XXX grade will be the best in that regard. This might be a case where you could do a 3D print in black nylon, but that will require a decently pricey machine. The appearance of the printed part won't be as good as a machined part, most likely.

Clearly, the metal ring was made from a larger sheet that was either run through some sort of roller setup to produce the pattern of small holes on a larger sheet, or similar tooling used on a flat sheet in a press. For a machine that received the manufacturing attention that the Enigma machine did, I suspect no expense was spared in making the necessary parts or the tooling to make those parts.

boslab · Nov 28, 2020

The diamond pattern looks rolled, a small hand roll would do that easily, I’d guess the diamond pattern was part of a flattening process similar to roller correcting extrusions, instinctively you’d think the pattern was the aim, not a by product of the sheet being pulled through, the resultant pattern was probably the tension rolls gripping the sheet, I’m guessing of course before you stick a red hot poker up me arse cold end first so I burn my hand trying to extract it.
Mark

Forestgnome · Nov 28, 2020

Winterfalke said:
From what I've been told, that 'stippling' is made by pressing it with an array of diamond shaped points, and is done to make a sheet flat. I don't know the specifics, I've heard it mentioned a few times in horology.

That's where I've seen it, inside clocks on the supporting frames.

sfriedberg · Nov 28, 2020

The diamond pattern "stippling" is a form of planishing. It's part of a flattening process that simultaneously removes stresses from the material so it will stay flat.

Joe Gwinn · Nov 28, 2020

That is exactly right, but I don't know the name of the process.

Joe Gwinn · Nov 28, 2020

bmklawt said:
I'm working on building a replica of the German Enigma Machine and I'm looking for something that resemble Bakelite, preferable something that can be poured into a mold it needs to resist heat as well and Bakelite so I can solder brass contacts that pressed or molded into it more more importantly it needs to look like Bakelite.

There are plenty of castable black epoxy potting/casting resin systems available. Talk to Master Bond and their competitors.

sfriedberg · Nov 28, 2020

Joe Gwinn said:
That is exactly right, but I don't know the name of the process.

I've usually seen it as either "stippling" or "waffle die flattening", the latter being a Japanese term translated into English, I believe.

Laverda · Nov 28, 2020

The ring with the stippling is a stamped part. This will tend to make the part warp (not always) a little bit. To remove the stress and make the part flat stippling is used. A set of dies would have been used to do this. One side of the die is flat, the other side has the diamond pins to make the pattern. It is not decorative in any way. Just a fast way to make a thin stamped part flat. A process still used today.

bmklawt · Nov 28, 2020

I found this while searching for stippling
Sheet metal straightening/flattening plate/die

9100 · Nov 29, 2020

If you are going to make a number of rotors, consider making them out of Bakelite. It is easy, it comes in granular form, looks like black corn meal. Just heat the mold and push the compound into it, wait a while and take the part out. I made my molds from A2, hardened and polished, but you wouldn't need heat treat for a small number. In fact, it is a common technique to run the mold while it is still soft to make sure it will work.

With no prior experience, I made a mold for a voltage regulator case with molded in terminals, known as insert molding, and adapted a K. R. Wilson press to supply the clamp pressure and a landing gear cylinder for a Grumman Bearcat for transfer pressure and made thousands of cases.

Bill

thermite · Nov 29, 2020

boslab said:
The diamond pattern looks rolled, a small hand roll would do that easily, I’d guess the diamond pattern was part of a flattening process similar to roller correcting extrusions, instinctively you’d think the pattern was the aim, not a by product of the sheet being pulled through, the resultant pattern was probably the tension rolls gripping the sheet, I’m guessing of course

With yah up to this point.

before you stick a red hot poker up me arse cold end first so I burn my hand trying to extract it.
Mark

This part I do not get.

You are posting from Wales?

Why would yah WANT to remove it if it makes life Hell for the English, hot end outward, right where it was installed?

Yan Wo · Nov 29, 2020

What a cool project! Please keep us informed of your progress.

APD · Dec 5, 2020

FYI:

Divers find Nazis' Enigma code machine in Baltic Sea

Modern alternative for Bakelite and what is this stippeled metal

Aluminum

Attachments

Aluminum

Diamond

Diamond

Stainless

Diamond

Diamond

Titanium

Titanium

Stainless

Diamond

Stainless

Stainless

Diamond

Cast Iron

Aluminum

Diamond

Diamond

Stainless

Stainless

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