Vandercook Letterpress Electrical Schematic

Universal I Vandercook Electrical Upgrade Package

It has been quite a few exciting years since my lovely wife Karen Sawyer introduced me to the fascinating world of letterpress and we jumped into the Bremerton letterpress community feet first.  I decided to start this blog to share about the behind scenes life of maintaining our equipment, share solutions, share knowledge, and grow our community beyond the fun products my wife makes for her business. Two of my favorite pieces of equipment she owns is a risograph and a Vandercook Universal I.   This is just another way I felt i can contribute to my wife's letterpress business dreams.

In general, the Vandercook is a remarkably reliable machine, so it is shockingly rare that components fail. That being said, when things do fail, the parts are becoming harder and harder to find. The letterpress cards my wife makes are fantastic, but a lot more goes on behind the scenes.  Within the first month of starting work with our Vandercook my wife was printing a poster and mid operation the press stopped printing.  Being an electrical guy, I jumped into action to repair our machine.  When I opened the electrical panel, I was pleased to see a schematic was available even if it was disintegrating from age.  The only hard copy I had was for a Universal III which contained this image, Figure 1, which is very close to the Universal I electrical design.

Figure 1 Vandercook Universal III Schematic

Clearly this diagram was drawn around the establishment of Y14 drawing standards and early IEEE/ANSI documentation standards.

My final goal is to create an upgrade kit that takes the obsolete and dated relays, contactors, rectifiers, resistors, and capacitors and modernizes everything WITHOUT the introduction of modern digital electronics.  I want this kit to maintain the classical analog behavior of letterpress equipment.  I have already had luck replacing relays in the past but now I am redrawing the schematic, parts lists, and a fully installable kit that will be much easier to repair in the future.  The first challenge with all things is replacing the schematic.  Stand by for future updates.


After a long day at the office, I returned to find my lovely bride printing away before resuming my Vandercook adventure.  Her Meowdy sticker is by far one of my most favorite designs!  If you have a friend or special someone who loves cats, this is a must. 


That being said, back to the Vandercook fun.  I started redrawing the schematic then decided I would actually make this more educational for anyone who may be interested in the mechanics behind their Vandercook Universals.  The below image is going to improve every time I post to this blog.

Figure 2 Slightly Improved Vandercook Schematic

The Vandercook is a basic machine that uses standard 115 Volts Alternating Current (AC) to run a combination of relays, contactors, and timing circuits to make motors move forward and backwards, it really is that simple when you step back.  The red solid line in Figure 2 indicates the path of positive AC movement while the dashed redline indicates where rectifiers have been used to create basic pulsed DC.  I will use color to show the neutral path and inverse DC signals created in my following updates. 

While I don't love paper and letterpress quite like my wife, the challenges her letterpress equipment brings is always interesting enough to maintain my interests. More to come tomorrow folks! 


Day 3 is off to a slow start, work kept me late and my family always needs attention and support.  It is still my mission to provide the best support I can to the Bremerton letterpress community and hopefully the world of letterpress through this Vandercook exploration.

Today I am going to talk some basic ac and power circuit of the Vandercook.   Alternating Current is the basic power used in most American homes and commercial facilities and operates at a voltage of roughly 115 volts.  In an AC system when a circuit is completed (flipping a switch on) the electrons are free to vibrate back and forth based on the power level, frequency and current available. Figure 3 shows a sine wave that usually represents the back and forth movement of electrons over time.  While it may seem overly complex, it just represents the time it takes electrons to shift from side to side.

Figure 3 Sine Wave AC Example

This is incredibly important in decided what types of relays and contactors are needed for the future upgrade kit.  

To best understand how the Vandercook letterpress uses this power I have broken down the major functions/topics to:

  • Main Power Distribution
  • DC Power Circuits and Uses
  • Control Circuit
  • Forward Circuit
  • Reverse Circuit
  • Time Delay Function
  • Compound Motor Principles

The immediate concept to grasp at power on is the switch is turned to the on position in Figure 4 below, it completes the circuit.  This immediately causes the Ink Drum Motor to initialize and the lamp (identified as a NEON) to turn on. You will notice some of my symbols are changed from the initial drawing as I am trying to integrate modern symbols from the old letterpress schematic.  

Figure 4 AC Input Basic Functions

Things that are important for building my future kit is that the motor and light are both 115V AC. it is also important to recognize my main On/Off switch is a Single Pole Double Throw (SPDT) switch.  While I do not intend to put a light and a switch on the box, I will need a terminal board to interface with the wiring of these two objects.

I will show in following posts I will break down the sections of the press to show how the Control, Time Delay, Forward, Reverse, and DC power sections operate to drive the Vandercook.  To my Bremerton letterpress community and future following - good night!


Today I am focusing strictly on the DC power circuits and their uses within the Vandercook.  With my usual day here in Bremerton, letterpress is a bit of an afterthought until I get home.  I work in a data analytics line of work during the day and supervise a team of great people but when I get home, I find that working on this project is pretty relaxing. So DC Power...  The Vandercook, like many electronic devices has areas that depend on DC power or Direct Current.  Unlike AC power, electrons do not move back and forth, they move in a linear path forward or backward (positive or negative directions). Figure 5 below is a snip from the Vandercook electrical schematic that shows what is called a bridge rectifier. 

Figure 5 Bridge AC to DC for Shunt Field

A bridge rectifier is made from diodes and diodes themselves act like a door only allowing power to travel one way.  A bridge rectifier converts AC power to DC power These handy devices use four diodes to prevent electrons from returning to where they just came from and generate what we call full wave rectification DC power.  Figure 6 represents this change in electron transmission.

 AC enters bridge then exits

   Figure 6 AC to DC Signal Conversion

Based on the drawing, I am going to take some measurements, but it would appear that this means the motor is operating at both 170 Volts DC and -170 Volts DC to energize the motor and both the Shunt/Series fields inside the motor.  I am not going to dive in deep on this topic yet.  Suffice it to say, the motor is what we call a Compound DC motor and the fields in the image work within the motor for performance. 

In Figure 7 below, you will see another snap shot of the Vandercook schematic.  I have provided dashed blue and red lines on the outputs of the bridge rectifiers showing the path the DC sections of the schematic.  Fuses are also placed at the inputs to each of the rectifiers for safety reasons.  You will also see what is called a zener diode in the circuit which is used to maintain positive and negative DC voltages.  I may discuss the zener diode in more depth later but for now, the most important thing to understand that this DC section is the most important part of your Vandercook electronics.  The Forward and Reverse Contactors have significant roles here since they are essentially turning on either positive or negative 170 Volts DC.  Postive DC power makes the motor spin one way, negative DC power makes it spin the other.


Red and Blue Dashed DC Circuits

Figure 7 DC Voltage Circuits Identified

In Figure 7 above, two unique and more complex pieces of equipment crucial to DC performance of the Vandercook are the Break Adjust and the Speed Adjust. The Break Adjust symbol is an old symbol no longer used in modern electrical drawing for a device called a Rheostat.  This device adjusts resistance to increase and decrease voltage which will adjust stopping and starting due to the electrolytic capacitor.  The Speed Adjust symbol is also an old representation for what is called an Auto Transformer.  This device is a variable transformer that is designed to change AC voltages.  The purpose of these voltage changes causes the motor to spin continuously faster or slower based on the voltage into the bridge rectifier.

As i am considering the future kit that I am going to build and looking at Figure 7, It is important to note that I will need two traditional Bridge Rectifiers, 1 Zener Diode, Fuse Holders, Fuses, 2 Resistors, and 1 Capacitor.  The1 Rheostat, and 1 Auto Transformer (sometimes called a Variac) are mounted to the machine and are physically adjusted by the letterpress operator (in my case my loving and awesome artist and wife Karen Sawyer).  These tend to be a little more exotic parts so I plan to identify alternate new parts but they are not a priority to my planned upgrade kit just yet.  They will also need to be tied to my terminal board though.

I am a little ahead today so I may write some more for any parties following out there.  On behalf of the "behind the scenes wizard" of Pier Six Press, enjoy your day you wonderful Bremerton letterpress peoples!  If you found this post helpful at all, please take a moment to look at my wife's products.  She is a passionate artist with great taste in puns and gifty products.


Control Circuit Day.  The purpose of the control circuit is to slow down and prepare the cylinder starting and stopping motions.  For those of you from the Bremerton letterpress community reading this article, thank you!  Today I am going to focus on the control circuit of the Vandercook.  The Control Circuit is driven by the activation of two limit switches, 3LS and 4LS, which open and close the circuit to the Control Relay (ironically the control relay is a contactor and not an actual relay by definition). Figure 8 below is a snip of the drawing.  I will talk about Vandercook limit switches further below.  The small numbers scattered around represent wire numbers and I will use them to reference paths of current flow.

Figure 8 Control Relay and Limit Switches

When the press is first powered on the 2LS and 4LS limit switches are in the shut position.  Figure 9 and 10 shows the limit switches in their initial starting position.  With 4 LS pressed the Control Relay is prepared for activation by setting the press to run or pushing cycle on manual.

Figure 9 Limit Switches 2 and 4

Figure 10 Limit Switches 1 and 3

The limit switches change the direction of DC power to the motor depending on the position of the 4 at any given time.  The Vandercook limit switches open and close the paths necessary to active the relays and contactors.  When the control relay (contactor) is activated, it changes the positions of its contacts.

It is important aspect of our letterpress machine to understand contactors if we want to stick to making an upgrade kit.  Contactors make the nice loud audible clicking noise that we are accustomed to hearing while printing bad ass stationery or posters.  The main unique differences between relays and contactors are made for more power, they tend to have more safety features, and work at higher voltages.  Contactors were heavily used in early arcades and pinball machines.

When you look around the schematic you are going to see varieties of symbols that look like Figure 11 below.  These symbols represent the starting position of a contactor and have labels next to them for which relay or contactor.  To upgrade the contactors in this kit you need to understand the total number of Normally Open (NO) and Normally Closed (NC) connections. 

Figure 11 Normal Contactor Positions When Not Activated

If you count contactor positions in the schematic in Figure 12 you will find there are a total of 2 NO and 1 NC identified to the Control Relay (CR) and the CR symbol itself represents the power input to activate it.  Based on this detail I know the Control Relay has to be standard 120V AC power input with 2 NO and 1 NC.  If you google search "Contactor 120V AC 2NO 1NC" you will find many potential supply resources.  At this point I am not ready to make decisions on which ones to buy since a deep understanding of all relays and contactors in the Vandercook are needed before committing to a purchase.

Figure 12 Location of the Control Relay Default Positons

When the Vandercook input power flows across the control relay, it causes the positions of each CR to flip to opposite positions. This means that NC becomes NO and NO becomes NC.  The locaton of the CR points on the picture are next to Speed Adjust autotransformer and a 200 Ohm resistor in between forward and reverse power inputs to the motor.

October 02, 2022 — Robert Meehan