Heated Bed Kit Instructions

Transcription

1 Heated Bed Kit Instructions One of the wonders of 3D printing, is being able to print with a wide range of materials with different characteristics. Each material has its own properties, and often requires different techniques, different speeds and temperatures. For example, PLA demands a Hot-end temperature of around 205 to 220ºC. However, in order for the print to achieve a high resolution finish, a fan is required to cool the layers whilst printing. Other materials require a heated bed to print onto. Once the material is in place, the temperature must be around 70 degrees. This can be achieved with the installation of a heated bed to the printer. A heated bed consists of a circuit containing a heating element powered by electricity. By having the base of the printer at a high temperature, when the filament is extruded the reduction in the temperature difference between the Hot-end and the heated bed will reduce warping and aid adhesion to the bed. Please note that for a heated bed to achieve and maintain temperatures around 70 C, the bed has to receive a high and constant flow of energy. This will cause the printer to use a large amount of current, so before installing the heated bed, make sure it's absolutely necessary. The heated bed of a printer can consume about 10 amps, this is a high and potentially dangerous consumption level. If the heated bed were to be installed incorrectly, the risk of experiencing a short circuit increases, and that could be dangerous. Therefore, the installation of the heated bed is always under the customer's care and is the customer s responsibility.

2 Before we begin with the base installation, you'll find a general overview below of the connections for the purpose of a better understanding of what we are about to do. To add a heated bed the first thing you need to do is install the appropriate cables. When preparing the heated bed please bear in mind that the top surface, the one that you print onto, is the ridged side so this needs to be flat with no protrusions. The glass bed/fixpad will sit on top of it. In the kit you will find a heated bed. To install the thermistor you need to solder the thin black-red wire to the two wires of the thermistor it does not matter which way round the thermistor is wired. The thermistor cables are unprotected, so it is imperative to cover them with kapton tape or heat shrink tubing (this is supplied with the 3D Print World Prusa i3 printer kit) for a more secure connection. Note that these are very thin wires, so please be careful. Place the thermistor in the centre of the heated bed with the wires on the smooth side and poke the thermistor through the hole in the centre, so it is flush with the surface of the heated bed. Lay the wires along the smooth side of the heated bed and secure with kapton tape or Ty-Rap. Next you need to attach the supply cable (see next picture). Solder the thicker cables to the silver edges of the heated bed on the smooth side. It's very important that the cables emerge from the bottom of the base so that they are not disturbed when printing. Solder the wires to the metal pads to establish contact.

3 Do not worry about the colours of the cables, the heated bed has no polarity. *** Along the bottom edge of the heated bed there are 6 holes that can be used to install two LEDs and a resistor, so that the LED lights up whenever you turn it on, however these are not included in the kit. The installation can be completed with two normal LEDs or SMDs. The two LEDs are to be placed in opposite directions. One of them will light up. Solder the resistor on the other (smooth) side of the heated bed. Once these cables (thermistor and supply), and the LED connectors, if you are using them, are in place, the heated bed will be ready. If you already had a bed installed on your printer please remove it. Get the base in place and screw it correctly. The smooth side of the heated bed should be down and the ridged side up (so the wires you have soldered are directly above the base platform). Please be careful when assembling the heated bed onto the base platform, the springs should be between the heated bed and the base platform. The glass can then be placed on top of the heated bed and it should be clamped into place. Please be careful that the clamps do NOT interfere with any of the contacts or the wires. With the base in place, plug the electronics in. We use a RAMPS 1.4. The thermistor should be plugged directly next to where the extruder's connector is. In Port T1. The heated bed must be placed on the output D8.

4 Also on the RAMPS 1.4 the input connector for the electronics, the two terminals on the right are for the extruder (5A), connecting negative and positive. The next two are for the heated bed (11A), which also goes in the same order negative and positive. At last, to connect the power supply correctly, you'll need a power supply cable that provides up to 350W. If you have a Prusa i3 Hephestos, replace the original power supply with the one in this kit as the original one does not provide enough power to feed the heated bed. Please consult a qualified electrician before proceeding with the preparation of the power supply. It is essential to disconnect ALL wires from the mains before continuing Ensure the power supply is set to 230v indicated on the side of the power supply. Using 13amp cable strip ends and connect to terminals Firmware installation: Everything is ready now, but the firmware of your printer doesn't know that you have a heated bed yet. Firmware installation: Everything is ready now, but the firmware of your printer doesn't know that you have a Hot- Base yet. The firmware needs to be adapted accordingly. I used the firmware of Prusa i3 Hephestos. To do so, I had to download the full firmware with the corresponding.ino file. This link leads to the github repository, where you can download the whole firmware. You must open the "Marlin.INO" file with Arduino IDE and find the file tab named: "configuration.h". In that file you'll find a line that says "#define TEMP_SENSOR_BED". In this variable, change the value 0 for the value of your thermistor, it usually is 1. With the value already changed, check that the selected board is "Mega 2560 ", and that you have selected the correct serial port. Click on the Icon to the left so that the printer may load the code. If everything went well, you'll see that you have two temperatures on your LCD screen. The left one would be the thermistor's temperature and the right would be the Hot-Base's. If the base temperature indicates 0, it can mean two things, either you are in an area that is too cold (warm up;)), or that the thermistor has yet to be set correctly and needs to be double checked. We are almost there. The printer is ready, but before we generate the Gcode, we have to state that we have a brand new Hot-Base. I use Cura, and to do so with this program, I have to access "Machine" -> "Machine settings..." and select the box "Heated bed". To your left now set the desired temperature for the hot base. Around 70ºC is usually good, but that depends on the characteristics of the materials you're using.

5 It's finally ready. The hot base should heat up correctly now, which means that you should be able to start printing. Please exercise extreme caution, do not attempt to touch the base with you hands as you could injure yourself. Extra security measurements: Any extra security procedures should always be more than welcome. The hot base is a component that has a very high level of energy consumption, minimising risks should be a priority and an option we shouldn't simply pass on without giving it a thought first. Personally, I don't like to much energy flowing through my circuit board, I prefer it to leave directly from the power source if possible. For that, you can add extra components like for instance a relay. A relay is an electromechanical device that acts as a switch. It has two parts, an entrance with a Coil that when activated creates a magnetic field that enables the second half of the relay. The second half would be the output. The output consists of a switch that when activated, the input switch closes. We'll connect the input to the output D8. So that whenever we turn on the base, the D8 output is activated and the output relay close's and allows the Hot base to operate directly from the power supply. To the output, we'll connect in series the power supply and the relay output. This way the relay output will act as a switch itself. The circuit would look like this. This way we'll avoid the flow of energy of the hot base going through the electronics, instead, it'll go directly from the source through the relay, and straight to the Hot-Base. Keep in mind that the input of a relay is a Coil. When activated,the Coil generates an electromagnetic field due to the energy that flows through it. Whenever we stop feeding it with energy, the coil returns to its resting state holding a residual charge and that could damage our electronics. As we do take security matters seriously, the best thing to do would be to place a Diode anti-parallel to the relay's input. This would function as a filter whenever there is an unwanted current, so that instead of going through the electronics it passes through the Diode. A Diode has two pins, Anode and Cathode. To flow through the Diode, the current has to go from the Anode to the Cathode. Therefore, the Diode should be placed anti-parallel to the relay's input our output D8. What we'll do whenever the bed is functioning, is close the Diode's circuit so that it doesn't work. Whenever it's the other way around and the Diode does work, it would take the current generated by the Coil. With these improvements, you have installed your Hot base in absolute security. In case studies, you have to weigh the pros and cons. The pros of having a Hot-base are being able to print with materials like ABS and the improved adherence. Clearly a Hot-base is and extra for the printer, that gives us the chance to do things that without it we simply wouldn't be able to do, so it's up to you to decide. The cons would be, the high power consumption, changing the printer (which may compromise it's security), the risks of having a high flow of energy going through the electronics etc... Is it really worth it?

6 It's finally ready. The heated bed should heat up correctly now, which means that you should be able to start printing. Please exercise extreme caution, do not attempt to touch the base with your hands as you could burn yourself.