Roaddog Labs Bart Electronics and Wiring

From Roaddog Labs Docs

Introduction | Bill of Materials |Frame Assembly |Y-axis Assembly | X-axis Assembly | Connecting X-axis and Z-axis | Heated Bed Assembly | Extruder Installation | Electronics and Wiring | Validation and Testing | Working with Files and Printing

If you have a 24 volt Mini Rambo Bart kit use the docs at

Configuring electronics

If you bought your kit from Roaddog Labs Ltd. your electronics package is pre configured with the proper firmware for your machine. No further firmware configuration is required.

If you are sourcing your own electronics the firmware configuration and source is at . This firmware is configured for a RAMPS 1.4 control package.

Mounting electronics

Required Parts

  • Fully assembled RAMPS controller
  • 4 x spacers
  • 4 x M3 screws and nuts (most boards use a 16 or 20 mm long screw

Attach the standoffs to the outside rear support of the left had frame as shown in the picture.

TODO: add mounting pic of spacers


This diagram is a general reference to give you an overall idea of how the RAMPS integrates into your system. The wiring details for your kit are slightly different than this diagram so use the detailed instructions for each step.

RAMPS wiring diagram.

Endstop wiring

The kits use plain switch mechanical end stops. The switch is wired in the "normally open" condition. The push terminals mount to the NO and C connections on the switch.

File:Endstop wiring 2.jpg
End stop wiring End stop wiring at the end stop.

The RAMPS board uses a 3 pin connector for end stops. The end stop cables are included in your kit with the proper connectors and wiring for each end. The 12" (shortest) cable is for the Z end stop. The 24" cable is for the Y end stop and the 36" cable (longest) is for the X end stop. The Z and Y end stop positions are set to the minimum travel, or the MIN position. The X end stop is set to the maximum travel or the MAX position. More on this in the configuration and testing step. Plug the Z and Y end stops into the MIN position and plug the X into the MAX position.

For the plain switch end stop only two conductors are required. Each switch should be connected to the control board following this pic. Don't connect anything the the inside most pin on the board connector. Use only the outside two pins on each end stop board connector.

End stop wiring End stop wiring at the end stop.

Motors wiring

The connectors on the motors in your kit are wired and ready to plug into the RAMPS. The headers used by the motors are adjacent to the stepper drivers on the RAMPS. The positions are labeled on the RAMPS board.

IMPORTANT! Do not plug or unplug the motors while the RAMPS is powered on. This includes being powered by the USB only. Doing so may damage your stepper driver boards. Aways completely power down before pluging or unpluging the motors.

Color code for the Kysan motors provided with the Roaddog Baja kit..

Plug the motors in using the color scheme shown in the pic. That will ensure your motors will run the proper direction as defined in the machines firmware.

Note the two headers on the Z axis stepper motor driver.

PCB heatbed wiring

The heated bed connects to D8. It's also polarity isn't a concern as the heated bed is electrically a big, flat resistor. Still though observe the color code by connecting red to the + and black to the -. Either end can connect to the solder pads on the heated bed. If you are using these instructions for a kit not provided by Roaddog Labs Ltd your heated bed may be polarized. Check with the provider of your heated bed to make sure but usually if it doesn't have specific markings for the + and - the polarity shouldn't be a concern.

Thermistors wiring

The hot end thermistor plugs into T0 on the RAMPS. It's polarity agnostic so you can plug it in either way.

The heated bed thermistor plugs into T1 on the RAMPS. It's polarity agnostic so you can plug it in either way.

(pic of thermistor wiring)

Power supply wiring

Your power supply is also called a PSU. Check the power supply is set for 110 volt operation. There is a small slide switch on the side of the PSU, make sure it is in the 110 volt position.

The mains cable is the cable that connects your PSU the power outlet in your wall. It is not included. You have to strip an end of a power cable and to connect to the power supply (L, N, G terminals). If you aren't sure ask someone with experience working with electrical connections to give you a hand.

(pic showing connections)

The power supply is connected to the RAMPS with two sets of wires. One connects to the first of the big green terminals, the other to the second. One of those terminals powers the RAMPS board, motors and hot end. The other terminal powers the heated bed. You can either strip both ends or you can use the included spade lugs for the connection on the PSU end. The RAMPS end requires a bare wire connection.

(revise pic of RAMPS to PSU connection)

Power supply wiring.

Final Assembly of Hot End

Required Parts

  • 1 x fan
  • 4 x fan duct screws
  • 1 x fan duct
  • 1 x completed hot end assembly
  • 1 x hot end mount clip
  • 2 x M3 x 25 shcs
  • 2 x M3 nyloc nuts
  • 1 x parts fan assembly
Fan & Duct
Fan with screws inserted.

We recommend mounting the duct with the over-hang at the bottom. Please keep it clear of the heater block - although the duct is made of very heat resistant polycarbonate direct contact with the block will melt and damage the duct.

Remove the fan duct from the HeatSink. Screw the screws into the fan such that the ends are just protruding from the other side of the fan. The sticker of the fan must face the heatsink to blow air over the heatsink, therefore the screws need to enter the fan from the side opposite the sticker.

Screwing fan to duct.

Using the 4 Plastfast screws and a Number-1 sized pozi-drive screwdriver, attach the fan to the fan-duct such that the wires exit the fan in a convenient location - preferably such that it can be bundled in with the thermistor and heater cartridge cables. The screws are a tight fit, do be careful not to strip the heads of the screw.

Fan duct clipping to heatsink.

Clip the fan duct to the HeatSink.

Cable tie all wires together.
  • Cable-tie all cables together as additional strain relief. The heater cartridge wires are very sturdy and the thermistor and fan wires should be cable tied to them for protection.
  • The cables should be secured to the carriage or end effector of your machine, the motion of the machine causing the wires to repeatedly bend near the hotend will eventually fatigue and break them. Just like all wires in your system thought should be given to minimum bend radius, repetitive strain, and fatigue.
  • It is important to ensure the wires of the fan and the thermistor cable are cable-tied and strain relieved in such a way that they cannot come into contact with the heater block at any time.
  • The fan should be wired directly to a 12v power supply as appropriate and be constantly running. Do not connect to a "Fan" output of a controller board or similar, these are for fans that cool the printed object, not a hotend fan which needs to always be running.
Hot Tightening

Doing the final tightening of the nozzle.

Hot tightening is essential to sealing the nozzle and heatsink together to ensure that molten plastic cannot leak out of the hotend in use. When done properly there is almost zero chance of leaks.

Using your host software or panel interface etc, set the hotend temperature to 245*C. Allow the hotend to reach 245*C and wait one minute to allow all components to equalise in temperature. Gently tighten the nozzle whilst holding the heater block still with a spanner and using a smaller 7mm spanner to tighten the nozzle. This will tighten the nozzle against the HeatSink and ensure that your HotEnd does not leak. You want to aim for 3Nm of torque on the hot nozzle - this is about as much pressure as you can apply with one finger on a small spanner. The nozzle does not need to be torqued down very tightly at all to form a good seal, when at lower temperatures the aluminium will contract and lock the Nozzle and HeatBreak together extremely securely.

Fan and Hot End mount

Hot end mount
Hot end mount clip
Preparing the fan.
Attaching the fan to the extruder

Extruder springs and screws

Wiring the Hot End and Fans

The hot end heating element connects to D10 screw terminal. It is polarity agnostic so either wire can go into either terminal.

Fans wiring

Plug the extruder fan in D9. The red wire is + and the black wire is -. This will allow your software to control the use of the fan.

(update pic to show plugged into D9 and not using the 12v aux)

E3D V6 Lite Tips and Tricks

In general the E3D-Lite6 hotend is highly tolerant of most printing conditions and is designed to accept the vast majority of filaments on the market. There are however some things to be aware of:

  • Filament must be within acceptable diameter tolerance. For 1.75mm this means 1.70mm - 1.80mm.
  • Excessively long retractions will cause issues by dragging soft filament into cold areas, because of the PTFE liner however Lite6 can cope with quite aggressive retractions without sticking. For direct extrusion systems you should use anywhere from 0.5mm-2.0mm, for bowden systems you might want to go up to 6mm. Retraction beyond 8mm should never be necessary. A good starting point for direct systems is 1mm, and 5mm for bowden setups.
  • The heatsink must be cooled! Heated chambers, fan ducts that restrict flow, and not having the fan running at 100% at all times are common causes of issues. The bottom 2-3 fins of the heatsink are designed to run a little bit warm, but the rest of the heatsink should run at near-ambient temperature.
  • The maximum temperature at which you should use your Lite6 hotend is 245*C - exceeding this temperature will cause the PTFE liner to begin to fail. Should your PTFE liner fail for whatever reason it can be easily replaced by removing filament from the hotend, then removing the liner tubing by depressing the collet and pulling up the tubing out of the hotend. You can then insert a new liner by following the PTFE assembly instructions above.
  • It is worth periodically checking that the PTFE liner is secured without any ability to wiggle. This is particularly true in bowden systems where effective retractions rely on the tubing being properly secured.

Introduction | Bill of Materials |Frame Assembly |Y-axis Assembly | X-axis Assembly | Connecting X-axis and Z-axis | Heated Bed Assembly | Extruder Installation | Electronics and Wiring | Validation and Testing | Working with Files and Printing