Our story today is about a sheetfed offset printing machine that was not destined to live a long and happy life. It was produced for a very short period of time – from 1984 to 1994, but it is notable for the fact that it was an attempt by Heidelberg to gain a foothold in a market that was still in its infancy at that time – the market of one or two-colour accent printing and to compete with cheap duplicators.

It can be considered the progenitor of modern digital printing solutions, which is the latest generation has a name Heidelberg Versafire. Of course, to reach today’s positions, Heidelberg still has a very long way to go with its Quickmaster 46-4 DI experiments, later with the Kodak NexPress and already in the 2010s with the Ricoh Digimaster, but all these machine series also have their roots in offset printing.

 

Where did it all start?

You’ve probably figured it out by now. We’re talking about the Heidelberg T-Offset series, small 28x39cm duplicators capable of running at speeds of up to 10 thousand sheets per hour.

Until the early 80s, Heidelberg already had experience in the small-print niche. But the only printing machine GTO was too little automated and rather bulky for the office, and gradually new unexpected players from the American and Japanese market – Hamada, Ryobi, AB Dick – began to appear in the niche of accent printing. It was in the early 80’s that copy parlours, which specialised in printing cheques, forms, tickets. They were simple, easy to maintain and not requiring special conditions, flourished.

The advantage of such copy parlours was that it did not require huge premises and high-precision equipment. It could be opened close to the consumer – even in a neighbouring house or on a busy street. A bank or a large office could have its own printing area for documentation.

Of course, Heidelberg was counting on the success of the new machine. Demonstration buses were sent to customers all over the world, in which operators showed them the whole printing process – from plate making to trimming.

 

A versatile machine for short runs

The idea of cheap and quick print production was actively taken up by manufacturers of plates for printing. Materials could be lit in a small-format copy frame and developed in a compact processor. This made it easy to take a photograph of the original, which did not even need to be rasterised, and immediately produce a plate for it.

Ink unit

The requirements for the ink machine of such a machine are also different from those of large format machines. There are no large areas to seal. All it’s needed from the machine is only required to roll out the printing ink well and evenly.

In the Heidelberg T-offset, a completely unusual ink system is used. The ink was rolled onto the plate by… just one large-diameter roller – its size was half the diameter of the plate cylinder.

The scheme of the ink unit meant that the paint flow was divided into two streams. Only three rollers fed all the ink from the ductor cylinder to the knurling roller. At the same time, the other seven rollers simply spread and levelled the knurled paint over the surface of the large knurling roller.

Dampening unit

Depending on the printing plate used, the machine could have one of two types of dampening units.

1. Combined unit – dampening was not applied to the plate, but to the large rubber plate roller. On its surface was created a film ‘ink – water’ in the required proportion, which was applied to the foil plate. The design of such a printing machine included several other rollers, which you will not find in modern machines. These performed the function of etching the foil plate.

2. Conventional separate dampening unit with cloth rollers that formed the film ‘ink – water’ on the plate cylinder.

 

The construction of the printing machine

Despite its appearance of lightness, the machine was precise and designed for long-term operation.

The plate and printing cylinders were cast from steel alloy, while the offset blanket cylinder was hollow inside and made of aluminium.

The cylinders had slip rings, which increased the stability of the machine and achieved really high dot quality. But most importantly, the cylinders were mounted on tapered needle bearings without clearance, as in big multi-colour presses. The construction of these quite expensive bearings are highly accurate and almost wear-free.

Steel grippers with replaceable polyurethane pads could be repaired and worn ones easily replaced.

The offset cylinder was fitted with a quick washing device using a special roller with low material density. It is shown in the figure below (1). Its rubber was only designed to use environmentally friendly materials. When the printer tried to wash the machine with cheap paraffin, the roller would change its structure and swell. It was quite expensive to replace the roller, and over time printers reverted to flushing the offset web with a regular rag…

 

Feeder and delivery

The sheet feeding was carried out by the narrow side.

There was no side stop in the machine. The operator could simply move the foot by adjusting the side bar (2). The precise side feed adjustment required for full-colour printing was out of the question – for one or two-colour printing on bills or envelops, such an alignment was quite sufficient. It was assumed that the sheets of paper would be neatly trimmed and the machine would not print jobs requiring a second run of sheets.

There were two versions, differing in the design of the delivery. They differed in that the TOK had a tray stacker, while the TOM had a table that could be dropped to the floor.

 

Accessories

This is the most interesting part of our review. The T-Offset series was conceived as the basis for copy shops, whose equipment can quickly fulfil any job. That is why an impressive list of optional equipment has been prepared for the machines.

 

That’s not all. The printing machine could be connected to a sorter with 60 or 120 shelves. In total, up to 10 towers with a total of up to 600 shelves could be connected in line to the machine! You have to agree that in this configuration the printing line already resembles modern digital printing machines with sorters.

But the most incredible piece of optional equipment on the Heidelberg T-Offset machine was the online plate exposing device manufactured by Bacher. Using a feed tray, a paper original was inserted into the camera. It was photographed there, exposed on a special silver-containing plate material, developed and fed into the machine.

 

Advantages and disadvantages

Heidelberg managed to create the best in its class offset printing duplicator, which was to be a worthy replacement for the famous Tiegel letterpress machine. It was as automated as possible, which for the mid-1980s looked like an emerging printing standard.

The ink unit was quick to produce quality prints in as little as 50 sheets. The length of the circumference of the large knurling roller exceeded the length of the surface to be printed, and templating was completely eliminated. The small ink capacity allowed quick adjustment for new work. But operation showed the serious disadvantages of having a single knurling colour roller. The slightest damage to the roller, which could be caused by a foreign object, resulted in a printing defect. The roller was very expensive and difficult to replace.

Despite the presence of an impressive list of peripherals, the plate setting itself was not fully automated. The machine included both a quick-clamping bar, which had to be closed with a special tool, and a bar with hooks. The machine could automatically insert and clamp only the non-perforated plate. The full automatic plate changing system for all kinds of plate material could not be installed on the machine.

 

Plates that were common in the accidental printing

1. Aluminium printing plate with straight edge or perforated edge. Perforation pitch 12.5 mm, perforation diameter 4.5 mm. The standard was widely distributed and was called ‘International’. Plates are even today the most common form material in offset printing.

2. Aluminium printing plate with perforated edge. Pitch of perforation is 12,7 mm. Perforation diameter – 4 mm. This perforation standard had the name ‘Pinbar’. Exposure method – photographic camera followed by etching. Circulation resistance – up to 10 thousand impressions.

3. Aluminium printing plate with perforated edge. Perforation pitch 29.6 mm. Perforation width – 5.5 mm. Exposure method – photo camera with subsequent etching. Circulation resistance – up to 10 thousand impressions.

4. Polyester printing plate based on silver-containing copying layer. Exposed by direct photographic process. It was possible to use with perforated edge. Circulation resistance – about 20 thousand impressions.

5. Paper-based printing plate with non-perforated edge. Manufactured by laser printer or copier, but requiring etching with zinc oxide. Print resistance – up to 7-10 thousand impressions.

6. Paper-based printing plate with non-perforated edge. Printability – up to 3,000 impressions. Produced on a copier or laser printer.

 

Conclusions

But most importantly, the machine was not at all adapted for printing multi-colour raster works, where exact colour matching was required. It was conceived as a complement to a multi-colour machine. Thus, the possibilities of the Heidelberg T-Offset were still very limited.

The format of the machine was the same as the former letterpress Tiegel machines – 28×39 cm. But soon everyone found out that it was inconvenient and did not match any other printing machine. New machine could not work in tandem with the Heidelberg GTO’s 34×46 cm and 36×52 cm formats.

Obviously, Heidelberg relied on the T-Offset series of printing machines, but the huge amount of peripheral equipment produced, such as various feeders and sorters, made the machine unreasonably expensive. In addition, the solution turned out to be inconvenient due to the ill-conceived system of ink rolling and non-automated system of plates setting.

After ten years of production, the series was discontinued in 1994. But Heidelberg did not give up producing equipment for the excitation niche, and the T-Offset model was replaced by another machine, the Quickmaster 46, where the engineers did a lot of work on the mistakes.

Used photos from public sources and materials of Heidelberger Druckmaschinen AG