I - How I relived my Rapman with standard electronics (Hardware).

Hello everyone.

I like to share with you my experience of rebirth of my printer Rapman 3.1 after the board began to have a malfunction.

First of all, I want to thank all the bloggers who have shared their expertise in internet in order that those that little we know of electronics and programming, we could go out of the difficulty of a still printer for lack of supplies.

I note that this procedure is applicable to any electronic replacement for Rapman.
(excuse me my bad english)


THE STAGE

My situation six months ago was like many users of a Rapman printer: the display is burned and for some reason the board did not reach the work temperature. I changed all the Hot End components, twice (resistance, thermistor and all the tedious process of laying the fire-cement and re-armed the whole, with the wiring and the verification of resistance in Ohms). But nothing was the same and was working blindly, without display. I even tried to adapt a generic LCD12864 display to the PCB using SPI connections, but the languages ​​(hexadecimal vs. binary) were not compatible, nor voltages.

Bits from Bytes manufacturer had merged with 3D Systems and was no longer technical or had parts support. as it would: dead.

Searching the web, I saw many manufacturing projects of RAMPS printers and wondered: will be possible to adapt a standard electronic to my printer and not have to rely on a manufacturer that no longer exists? And I began to inquire about it.

After much research, I found that all 3D printers have the same operating principles, but differ in parts and mechanical structure thereof.

The first was set to Rapman is a Cartesian printer and you have several options to revive: the electronic components were available in Ebay, the board control could be Arduino (RAMPS), the firmware had several chances but Marlin seemed to have the same characteristics of the propietary Rapman firmware. Then I looked at several similar printers, with the precision and quality in the end result to which I was accustomed and discovered that the more compatible printer Rapman was Ultimaker Original, with some technical differences. I also remembered that one of the founders of Ultimaker was a regular visitor of Bits from Bytes  Forum (Erik de Bruijn). Then, I could not be so wrong with my choice of converting my Rapman to open Ultimaker electronics.

I went to Ebay / Aliexpress and found all the necessary electronics (v.g the shield board https://www.aliexpress.com/i/1965450883.html). I hope it's still available:

Arduino MEGA 2560 R3  Board - Original	MEGA Ultimaker  Shield Board 1.5.7
Pololu A4988 Stepper  Drivers with heatsink	LCD 12864  controller module with SD reader

With the shipping cost was worth only U$ 100.

And I had no doubt apply to relive my printer.

It should be noted that there are other options on the market that integrate all components on a single board (eg Rumba) but I wanted to be in control, in the event that some component burned, and it can be easily replaced.

Then I describe the steps needed to revive my printer Rapman 3.1, which apply to any electronic replacement, but in my case, it works beautifully with Ultimaker board.


BOARD, CABLES AND CONNECTORS

The connectors on the Arduino MEGA board fit firmly with the pins into the bottom of the Ultimaker Shield, in this way:

The printer cables must lengthen by splicing wires of the same features and preferably welded joints. In an electronics store can be purchased a female connectors, compatible with the board Ultimaker shield:

- 3 pieces of 2-pin (endstops)
- 4 pieces of 4-pin (axis motors and extruder)
- 1 piece of 3-pin (thermistor)
- 15 jumpers

Place each wire into a pin, tighten it with a clip and see the small retention tab on top curves outward.

Insert the wire into the connector until you hear a slight click and the small tab clicks into place. Make sure the cable is fully inserted and that they are securely in place.

You must be very careful with the order of the motor cables and extruder axis. You could burn the board or the motors. The order should be:  BLACK - GREEN - PINK - BLUE

All cables are connected to the board, as it is shown in the picture:

ENDSTOPS:  Z - Y - X
AXIS MOTORS:  X - Y - Z
THERMISTOR:  T
EXTRUDER:  EXT

Note that the hot end gray cables connect directly, without connector, in the first terminal screw - BLUE -.

If you have a Rapman fitted with heated build plate and/or two extruders, a proximate diagram of connections would be as follows (note that the endstops of Ultimaker are 6 and Rapman are 3; for proper connection refer to the photo above).

STEPPER DRIVERS

This is a very delicate way and makes the difference between right or wrong overall 3D printer and motors performance.

The Pololu stepper drivers are placed with their heatsinks on the board in the direction shown:



CAUTION: the stepper extruder is placed inverted (see picture). A bad connection can damage the board.

Black jumpers are placed on the pins of the board as shown in the picture.

All motors operate at different voltages.

For the stepper drivers of 3.1 Rapman you should adjust the voltage to supply enough electricity to motors or avoid overheating that can shorten its life or burn.

The Rapman comes with a 12V power supply. Connect it to the red board. With a small screwdriver and a voltmeter, you must adjust the voltages of each stepper driver:

AXIS Z:  1.3V
AXIS X - Y:  1.0V
EXTRUDER:  1.1V

The ground of the board is taken at the point shown in this picture, next to red LEDs:

THIS PREVENTS A SHORT CIRCUIT DURING THE CALIBRATION TEST.

NOTE: This board operates at 18 volts to achieve high speed and performance and reach the working temperature. Think about placing a power supply of a laptop (18V). But this is a limitation of the resistance that heats the hot end, which requires that voltage. In a very later entry I will change the extruder by another standard of 12 volts (E3D V5) and thus take advantage of the original power source of Rapman, as well as control the fans directly from the board.


LCD CONTROLLER MODULE - WITH SD CARD READER -

This component is what makes the difference and autonomy of the 3D printer. It is the controller module of the print functions in real time, as was the original board of Rapman:

- Temperature control of each component
- Preheat the hot end
- Cooldown
- Coordinates of printing, in values X Y Z
- Movement distance of the extrusion head in decimals
- Sending the extrusion head to HOME
- Control of speed, acceleration, retraction, steps of the motors, etc.
- Select the file to print -SD card-
- Control file execution
- Pause printing or termination
- And much more

At the rear of the module, place the jumper on pins shown below:

Data cables must be connected to the board:

NOTE: After installing the firmware (later described how), if there is no image on the screen, you must swap the connectors on the board.

And so are the connections to the new electronic, using the original fan with independent power:

Check all voltages with the multimeter, before burning the firmware on the Arduino board.

In a few days, I will describe the process of installing the firmware, final adjustments and some recommendations to have full functionality of 3.1 Rapman printer.

Good luck !