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Last page update: 14 January 2017


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PAPER TAPE

Hellschreibers print transmitted and received text on paper tape. The width of the paper depends on the mode that the Hellschreiber uses: (quasi)synchronous vs. start-stop. The machines that operate in the (quasi)synchronous mode, simultaneously print two identical lines of text, one above the other. This requires wide paper tape. Hellschreibers machines that only use the start-stop mode only print one line of text. This requires narrow paper tape. Machines that can operate in both modes (e.g., the Hell-80) require wide paper.

Standard wide Hellschreiber paper tape has a nominal width of 15 mm (19/32 inch). The 1940 and 1941 Feld-Hell manuals (ref. 1, 2) have the following specification for wide paper printing tape ("Registrierpapier"):

  • width:
  • 15 mm , -0.1/+0 mm (ref. 1)
  • 15 mm, +/- 0.1 mm (ref. 2)
  • thickness: 0.065 mm (25.6 mils), +/- 0.005 mm
  • core diameter (ID):
  • 29 mm, -0/+1 mm (ref. 1)
  • 30 mm, +/- 1 mm (ref. 2)
  • Note: the hub in the two paper trays of my Feld-Hell have an outer diameter(OD) of 28.0 and 28.25 mm respectively, whereas the hub in my Hell-80 machine has an OD of 29.0 mm.
  • roll length: 250 meters.
  • ash content: max 4% for non-gummed paper (ref. 3)
  • gummed: like pre-gummed postage stamps. Sections of printed paper tape were moistened on the back and then glued onto a telegram form ("Fernschreiben"). Supposedly, the gumming was sufficiently moisture proof ("feuchtigkeitssicher") such that moisture in the air would not make unprinted rolls unusable. This was not necessarily the case in humid climates. Also, decades-old original rolls may have absorbed enough moisture over time, that the tape has become glued to the roll. Gumming is not required for printing.

This 15 mm wide paper tape is used in the following Siemens-Halske and Hell Co. Hellschreiber machines:


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Fig. 1: a stack of 15 mm wide rolls of paper tape and a roll with "DIN 6720" stamp


These rolls of tape were also covered by the DIN standard 6720 (S3). The NATO stock number (NSN; a.k.a. National Stock Number) for Hell-80 rolls of paper tape is 7530-12-121-4545. NSN -4545 is in the same family of "Fernschreibgerät Band" as -4546 and -4547.

In the Feld-hell machines (2.5 characters/sec), the tape moves at about 28 m per hour, so a standard a 250 m roll will last for 9 hours of continuous printing. The Presse-Hell and Hell-80 printers move at twice this speed (5 chars/sec).

Standard narrow Hellschreiber paper tape has a nominal width of 9.5 mm (3/8 inch). It is used in the following Hellschreiber machines:

The start-stop machines typically print at 6.1 chars/sec and the tape moves at 1.1 m/min. The German national railway system (Deutsche Bahn) used about 60 thousand (!) rolls of gummed paper tape each year (mid 1960s, ref. 7).

The type of paper makes a big difference in printing quality. The photo below show prints on narrow tape (my Hell 72 "GL" machine) and on wide tape (my Feld-Hell machine). Both were printed with the same ink roller and ink! The narrow paper (at top in Fig. 2) happens to be denser (less translucent) and smoother/slicker than the wide paper that I used. The latter clearly shows dispersion of the ink, due to capillary wicking. Obviously this is not desirable. When using water-based or alcohol-based ink, instead of the recommended oil-based ink, this effect becomes worse.


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Fig. 2: the effect of the type of paper on the print quality - the same ink was used in both cases


The paper has to be absorbant enough, such that the ink is quickly bound to the paper, without dispersion. Ref. 6. First of all, this means that the paper should not be fully satinized. Satinizing (passing the paper through heated pressing rollers) compresses the fibers and fillers in the paper. This reduces dust production, makes the paper thickness homogenous, makes the surface smooth but not slippery, and only slightly reduces absorption. The paper also should not be fully sized. Sizing (D: "Leimung") of the surface, or of the entire paper, makes the paper hydrophobic. Sizing is done with starch or gelatin. It facilitates printing with ink that is watery or contains solvents. The paper should also not contain minerals (i.e., it should have a low ash content). Minerals make the paper act like sandpaper on the thread of the spindle helix.


PAPER TAPE CUTTERS

These 15 mm and 9.5 mm wide rolls of paper tape ("Schreibrollen") are no longer available off-the-shelf. So the options are:

  • custom ordering - this is rather expensive, though a large group-buy of several hundred rolls makes it (more) affordable
  • take standard un-oiled paper punch-tape used in telex teleprinters and CNC machines. Ref. 4. This is not quite as expensive, but somehow its width has to be cut down from the standard 11/16 inch (≈ 17.5 mm) to 15 mm. Even such punch tape rolls are becoming hard to find, especially the un-oiled ones... Oiled tape is used for auto-lubrication of high-speed machines, which is not what you want to use to print on...

Years ago, Remmelt-Jan Warries (PAØRJW, SK) constructed a very nice motorized paper tape cutter. It consists of an electric letter-opener (with integrated pencil sharpener) and a motorized "reel to reel" telex punch-tape transfer spooler. The letter-opener just happens to cut off 2.5 mm (≈ 0.1 inch) - exactly what is needed when starting out with telex punch tape! The cutting speed is limited by the letter-opener. The speed of the spooler was controlled with a variac (a.k.a. variable auto-transformer, rheostat). A standard roll of tape could be processed in about 4 minutes (about 5 km/h, 3 mph). Remmelt-Jan sliced over 32 km (20 miles) of tape this way, all with the original cutter blades of the letter-opener!

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Fig. 3: the cuter set-up - letter opener, guidance for entering & exiting tape, and the spooling machine



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Fig. 4: tape guides from an old VCR help the tape move through letter-opener in an orderly fashion

(the blue ballpoint pen tube diverts the 2.5 mm cut-off away from the "main" tape)


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Fig. 5: 330 meters (1000 ft) of 2.5 mm wide cut-off - perhaps suitable for a "micro-Hellschreiber"?



FELT INK ROLLERS - "FARBROLLE"

All Hellschreiber tape-printers from Siemens-Halske and the Hell company use the same felt ink rings ("Farbrolle", "Einfärberolle") to keep the printer spindle wet with ink:

  • Dimensions:
  • 30 mm outer diameter (≈1 3/16 inch)
  • 18 mm inner diameter (≈0.7 inch)
  • 14 mm width (≈9/16 inch)
  • Unfortunately, this is not a standard size for felt rings per DIN 5419 - the nearest standard size is "4", which measures 27x17x4 mm.
  • Material: hard, dense felt (which is matted, condensed, compressed wool fibers)

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Fig. 6: small metal box with a spare felt ink roller - part of the Feld-Hell spare part box

(original unedited photo: courtesy John Alexander Wilson; used with permission)


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Fig. 7: felt ink roller on its holder and two spare rings



Life expectancy of ink rollers depends on the level of saturation with ink and spindle speed. As a rule of thumb: rollers are good for inking/re-inking three times, and for printing 15 rolls of paper per inking. That is: 45 rolls of paper. Ref. 6.

When not in use, tightly wrap the ink roller in plastic food-wrap film from your kitchen. This will slow down the drying-out of the roller. Once a ring has been saturated with ink and the solvents of the ink fully evaporate, the ring becomes very hard and dry. In many cases, re-inking will take care of this. Dirt and dust can be removed with a brush and a damp sponge. If alcohol-based ink was used (water-based ink should not be used, oil-based ink is recommended), it may be possible to dissolve dried ink deposits by soaking the ring completely in rubbing alcohol for a while, and then draining and immersing several times.

Whereas WD-40® should not be used for lubricating Hellschreiber parts (or anything else that you care about!!!), it may be used (lightly) on felt ink rollers, if (oil-based) ink has dried out and the roller has become hard. Thanks for the tip Andrew (SM6MOJ).


INK-ROLLER HOLDER - "FARBROLLEHALTER"

The felt inking rings are slid onto a holder that comprises a thin-walled steel cylinder and a bakelite knob. Like the felt rings, the holders are also compatible with all Helslchreiber machines. There is some minor variation in the shape of the knob. Also, the holder of the Hell-80 has a small securing spring that clips onto the tip of the small shaft onto which the holder is placed. This does not appear to be essential.

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Fig. 8: holders for felt inking rings

(top row: Feld-Hell, Presse-Hell, start-stop-Hell; bottom row: Hell-80)

The cylindrical metal part of the holder tends to corrode over time, especially if water-based ink is used. The design drawing below is based on my measurements of two original ink roll holders.

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Fig. 9: my design drawing for an ink ring holder


I had several of these "new old design" holders custom-made out of aircraft-grade aluminium (yes, $$$), for my six machines. They are anodized black ("schwarz eloxiert") to make them corrosion resistant (and resemble the original black Bakelite).


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Fig. 10: newly produced ink roll holders


The next two photos show the parts of the ink roller assembly:

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Fig. 11: ball bearing retainer ring, ball bearing, hub, and ink roll holder with felt ring


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Fig. 12: the flanged hub onto which the ink roll holder is slid


The original ball 1930s bearing is a standard type 634. It is un-shielded and its dimensions are 4x16x5 mm (bore x outer diameter x height). I replaced the one of my first Feld-Hell machine with a 634-ZZ, which is the same ball bearing but double-shielded and "greased for life".

Fig. 11 above shows the ball bearing retainer ring on the far left. It has two small blind-holes on one side. These are used when unscrewing this retainer ring. I do not have the matching two-prong tool, so I made a simple-yet-effective jig with two cut-off nails that are clamped in a bench vise:    

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Fig. 13: simple 2-pin jig for removal of the ball bearing retainer ring



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Fig. 14: the ink roll lever - hub and ink roll holder removed



INK

The 1941 Feld-Hell manual (ref. 2) recommends using ink ("Schreibfarbe") that is a "colloidal solution of pigment in oil". Here, colloidal simply means that the pigment particles are so small that they always remain evenly distributed throughout the solution, and do not settle to the bottom of the container. The oil-base minimizes drying out of the felt roller and collecting deposits of ink on the spindle.

The same manual prescribes the use of special ink "HB 45 violett". According to ref. 5, this is a dark-violet colored special ink ("Spezialfarbe") named  Haberolin-Basolomin. Haberolin originally was a deep-black cloth dye (marking-ink), made by Wilhelm Haber. The "Wilhelm Haber Stempfelfarben" company was founded in 1873. The company still exists today (located in Lommatzsch, 160 km (100 mi) south of Berlin), under the name "Wilhelm Haber Stempelfarben Steffen Haeckel e.K." They have not responded to my various attempts to contact them, and I am not aware of a source of HB 45 ink today.

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Fig. 15: an original Feld-Hell ink bottle

(original unedited photo: courtesy John Alexander Wilson; used with permission)


Ink should be light-resistant, permanent, and pH-neutral so as not to damage the spindle surface. Ref. 6.

Water-based ink is not recommended: it causes corrosion of the thin steel bushing on which the felt ring is installed. Also, the capillary action of the paper causes such ink to be dispersed, making the printed text fuzzy shortly after being printed. Alcohol-based inks also tend to be rather "thin" and cause dispersion of the printed text.

So, ideally, oil-based numerator or recorder ink ("Registriertinte") should be used. Some non-oil-based alternatives are shown in Fig. 16 below, such as Pelikan dark violet "Stempelfarbe ohne Öl" (endorsing ink without oil). A similar product is made by Radex (= Kores). It comes in a small bottle. This is what I use these days; I buy them on-line or in an office supply store. The color is not critical, but obviously has to be dark compared to the paper. Another (slightly) thicker liquid ink is Edding T25 (e.g., black); this is basically professional drafters ink. Some people use Trodat-brand numbering machine ink (7051 is black).

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Fig. 16: various types of non-oil-based inks that people use with their Hellschreibers



I use Pelikan-brand endorsing ink on the roller of my home-built Hell-printer. It is thick and comes in a tube. The label says that it is intended for felt pads. Just what I needed. You just may want to use gloves when handling this type of ink!

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Fig. 17: black endorsing ink that I used on my home-built Hellschreiber printer



REFERENCES


External links last checked: March 2016


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©2004-2016 F. Dörenberg, unless stated otherwise. All rights reserved worldwide. No part of this publication may be used without permission from the author.