RD3D/1.0

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Revision as of 19:48, 17 September 2017 by Lkcl (talk | contribs)
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RD3D 1.0

Release status: in development

RD3D 1.0 eagle.jpg
Description
RepRap Due 3D Printing shield Arduino DUE based modular RepRap electronics.
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CAD Models
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RD3D v1.0 - Reprap Due for 3D Printing

This board is derived from Ramps 1.4.2 and has the following features and improvements:

  • Suitable for use with Arduino Due: uses 3.3v supply from Due, not 5.0v
  • Suitable for up to 24v on both or either Power inputs
  • Removed all double Stepper connectors (motors should be wired in series)
  • Removed all AUX except I2C, AUX4 (for LCD) and AUX3 (for SPI-Ethernet)
  • Removed MAX Endstops
  • Removed Thermal Pads to increase power handling capacity between layers
  • Added MicroSD Card (for porting RepRapFirmware)
  • Moved D8, D9 and D10 LEDs next to their outputs
  • Increased current capacity of 3V3 trace to MicroSD, AUX3 and AUX4
  • Increased Main Power copper pour (inc. to VMOT) widths, added extra VIAs
  • Moved Thermistor jumpers down to end of PCB, linked to closer ADC pins
  • Added UA78M08DCY 500mA 8V Power Regulator, to supply Arduino from up to 24v)
  • Added extra 6th Stepper Board. Can now do auto-bed levelling (triple Z)
  • Added Twin Header for 2 always-on fans (connected directly to Power In)
  • Added a SN74HC125 to the MOSFETs to achieve full RDSon (Due is 3.3v)
  • Added D11 GPIO (with a pulldown) to disable MOSFETs on Due startup
  • Added GND Shielding VIAs
  • Significantly adjusted pinouts so that wires do not cross (reduce EMC)
  • Simplified Copper pour: single GND on TOP and BOTTOM with low priority
  • Fully GPLv3 compliant (full CAD source always available)

Being based on RAMPS 1.4.2 it also has the following features:

  • Improved current-carrying capacity (1oz copper instead of 0.5oz)
  • Standard removable Blade fuses
  • Suppresion capacitors on endstops
  • Extra jumper on the reset switch

Design features gallery

Here are some of the design features, with images (in order), below:

  • LEDs next to each power output: Heater, Fans, Extruder
  • Improved copper pour for VMOT power (includes extra VIAs)
  • MicroSD card added; Thermistor terminals moved right next to ADC
  • Tri-state Buffer on MOSFETs (3.3v to 5v conversion for Due); D11 disables MOSFETs (defaults to off)
  • LDO with an 8V 500mA output supplies power to Due from input voltage, accepts anywhere between 12v and 24v

GPLv3 PCB Board Source code

Full GPLv3 source code is available at http://hands.com/~lkcl/rd3d

git clone http://hands.com/~lkcl/rd3d/.git

BOM, PDFs

Why is the RD3D Board being done? Why not use an existing board?

In the markets in Huaqiang Road, in the Futian District of Shenzhen, RAMPS 1.4 boards can be bought cash for around 27 RMB, which is about $USD 3.50. Adding an Arduino 2560 plus four A4988 cloned stepper drivers brings that total to under $USD 15. The STP55NF06L MOSFETs of course need replacing for the heatbed to operate but IRLB304PBF MOSFETs can be bought in the same market at ridiculously low prices.

However RAMPS is only really suitable for the 2560, which, being an 8-bit controller is really too slow, and it's extremely inconvenient to upgrade a RAMPS to 24v. It's not actually possible to upgrade RAMPS to pure 24v: it's necessary to do hybrid 12v (for powering the 2560) and 24v for the heatbed alone. If you want 24v for the fans, heater and Motors, this is not really possible without cutting tracks in the PCB.

In addition, the hard limit of 5 stepper boards makes it unsuitable for use in auto-bed-levelling scenarios (triple Z screws).

So if you prefer to use 24v all-round, or prefer to use a 32-bit microcontroller, or would like to consider doing auto-bed-levelling, RAMPS 1.4 is not an option.

So in looking around for alternatives, several came up. The extremely good Duet 0.6 would be perfect (and a reasonable cost at around $60), except it's no longer made. Likewise the Duet 0.8.5 is no longer manufactured: it was $USD 120 which is almost as much as an entire 3D printer may be sourced for in Shenzhen. The absolutely superb DuetNG is $USD 150, which is simply far too much when you compare it to $USD 15 for a RAMPS 1.4 plus 25660 plus 4 A4988 drivers, in Shenzhen.

Also investigated was RADDS (because it uses the same RepRapFirmware as the Duets) - unfortunately whilst it would be perfect it's also proprietary: PCB files are "available under request and only for non-commercial personal use". This is not the spirit of the Reprap movement.

Also investigated was Smoothieware boards. The team seems to have a good sense of camaraderie, excellent support and, being based outside of China, take considerable care in manufacturing and QA testing. Unfortunately, their manufacturing and sourcing takes place outside of China. Basically anything that is sourcing its components in Europe or the USA results in a huge premium.

Also, unfortunately, when boards are typically cloned by Chinese Manufacturers, a number of things happen:

  • They typically "tinker" with the design (adding in EMF and unacceptable noise)
  • They completely forget to label which version they are selling (including their own modifications)
  • They don't honour the GPL license or the spirit of the Reprap movement
  • They don't provide firmware source code
  • Actual manufacturing is often not properly QA'd

So there is this very strange and paradoxical failure to combine the best of a Western mindset with Asian pricing and sourcing. The R3D3 therefore endeavours to combine the advantages of Chinese component sourcing and manufacturing with a Western mindset where the GPL licenses will be fully honoured, and proper QA will be carried out to ensure that the resultant PCBs work 100%.

In short: there are no *low cost* 32-bit, 6 stepper, 24v Reprap 3D printing boards that fully honour the GPL and the spirit of the Reprap community, hence why it has been necessary to create one.

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