I love my Makerbot Replicator clone (CTC), but one of the things this and many similar printers don't have is auto shutdown. In my opinion the auto shutdown option is vital. I do long prints, sometimes over night and I want to go to bed without the worry of my printer running for most of the night after the print has finished. In my search for a solution I found how other people have achieved this, but I thought of what I believe to be a better, simpler solution. And the materials are under $5.

I hope this Instructable helps you solve the same issue. This system will work with other printers too.

Some of the advantages of using this auto shutdown setup are:

-No need to access the back of your printer every time you want to turn it ON or OFF.

-No timers or micro-switches, the printer will shut down as soon as the hot end has been cooled after the print is over.

-If both extruders have been used for the print, it will wait for both of them to cool down before shutting down.

-Printer Power switch will not be affected so you can always bypass the auto shutdown by just turning that switch to the ON position.

-Cheap and easy to find components.

Step 1: Step 1: Materials and Tools

Here is the materials list and links to where you can find them:

-Solid state relay ( link)

-Diode 1N4001 (link)

-Toggle mini switch (link)

-Push button (I modified a 3A 220v momentary switch so it will push a 16a microswitch, but I recommend using one like in the link) (link)

-Some heat-shrink or electrical tape

-Wires

List of tools:

-Soldering Iron

-Small flat screw driver

-Electrical cutters

Step 2: Step 2: Schematic

Here is the schematic for you to have handy while making all the necessary connections.

PLEASE NOTE:

Before starting work on your Makerbot or CTC, make sure the power lead is unplugged. DO NOT power the machine until all the connections are properly made and the cables well protected and insulated with heat shrink or electrical tape. DO NOT attempt to make any connections with the power lead on. You will be soldering some cables to the power AC cables. I don't take responsibility for any damage to you or your machine. If you make sure the power lead is off and you follow this instructable closely you won't damage your machine or electrocute yourself.... so please DISCONNECT THE POWER LEAD AND KEEP IT DISCONNECTED UNTIL YOU ARE DONE WITH THE CONNECTIONS.

Step 3: Step 3: AC Power Connections

Turn your machine over and locate the back of your power switch. There will be two cables connected to the switch.

Use some cutters to peel part of the insulation of each of the wires.

Use the soldering iron to solder some cables to the power wires and make sure they are properly insulated with electrical tape or heat shrink. The length of the cable will depend on where you would like to place the Solid State Relay. Connect the cables to the AC side of the solid state relay along side another two cables that will need to be soldered to the push button. The length of these cables will depend on where you would like to place your push button. In my case I decided to place it on the front of my printer where I can easily access it.

With this you will have the AC section done.

Step 4: Step 4: DC Connections

To make all the other necessary connections you will need to remove the plywood panel that covers the Mightyboard. This is easily done by removing one bolt at the right side of the printer and sliding the plate to the left of the printer.

Use the Schematic on step 2 to make the following connections:

From the negative side of each of the extruder cooling fan cables, connect two cables that will be soldered to the cathode side of each of the diodes. Join the anode side of the diodes together and solder a cable that will go to one of the side pins of the toggle switch. Another cable will go from the middle pin of the toggle switch to the negative side of the solid state relay (DC side).

Now you will have to get the 24V feed from the power supply. The negative wire will go to the other pin of the toggle switch and the positive wire will go straight to the positive side of the solid state relay (DC side).

I would suggest that you place the toggle switch on the front of the printer or wherever you can access it easily.

Step 5: How It Works

This is the procedure to use the auto shutdown.

Keep the printer power switch in the OFF position and make sure the toggle switch is the the position that feeds the solid state relay from the negative side of the power supply.

Momentarily press the push button, the printer will come ON and will stay on even if you let go of the push button. (If the printer does not remain ON once you release the push button, the toggle switch is in the wrong position.)

The rest is very simple. Once you start a print, wait for the extruder cooling fan to start, then turn the toggle switch to the auto position, the solid state relay will then be powered by the negative wire from the fan. Once the print is finished as soon as the extruder has cooled down (around 50c or so) the fan will stop, and the power to the solid state relay will cease turning off the printer.

Happy " worry free" overnight printing!

I love this system and I hope you do too. Please get in touch if you need any help with this project.