This overhauled hotend housing allows you to see the printhead easily, allows for adequate cooling of the heat sink, hides all of the wires by moving the plugboard behind the x-carriage, and also has a modular part cooling duct that can be changed if you don't like the current design.
Tired of not being able to see the print head easily, I found and printed an "open hotend" modification from Thingiverse. After a while, I got tired of seeing wires hanging everywhere and decided to rebuild the hotend with a different setup. After being unhappy with another rebuild, I decided to make my own hotend assembly and ended up with this!
All parts should be relatively support-friendly and shouldn't need too much help. The parts are oriented in the best possible way for printing. Exercise your judgment when adding supports.
It is important to note that this was intended to be printed out of a 0.3mm nozzle; I am unsure if some of the finer details (i.e. the open vents on ACi3M_Hotend-housing.stl) will print well coming from a 0.4mm nozzle. If anyone prints it from a 0.4mm nozzle, let me know how it goes. I recommend using additional bed adhesion techniques for that file's smaller details.
Make sure you read the directions before you start this project so you know what you're getting in to; some parts of assembly can be very difficult and frustrating. Needlenose pliers and a small mirror may be of great assistance.
This modification will cause the printer's hotend to be a little off center. Remember to add an origin offset of X = -2.6mm and Y = -3mm to recenter all of your prints.
Notice: A problem has come to my attention where Cura users are unable to enter negative values in their Nozzle offset X and Nozzle offset Y settings fields. This is a known bug in Cura 4.1 by the development team and they say it will be fixed in Cura 4.2. Getting the beta version of Cura 4.2 should fix the problem and allow you to enter the offset values correctly. (Thanks flupsiflo for bringing this up!)
Remember to share a make if you complete this project; I'd love to see how it turned out.
Other things of mine seen in this posting:
Fringe Science Warning Sign for 3D Printers
Make sure all of your parts fit together before you start working on disassembling your hotend. Also ensure that you will be able to begin threading screws with a reasonable amount of effort, especially in regards to the belt block.
Disassemble the Original Hotend:
It is recommended that you also unscrew your Bowden tube from your extruder assembly.
It is also recommended that you take a picture of the plugboard and all of its connections so you can ensure that everything is plugged in correctly when you work on that part of the assembly later.
Begin by fully disassembling your original hotend housing. Keep all of the parts when you do this because you will be reusing some of them later. Carefully cut the zip ties that hold the x-belt together.
Build the Hotend:
Begin by inserting the Bowden tube through the bottom of the hotend housing and running it up through the top of the housing. Insert the hotend into the housing and press it into the housing. The bottom heatsink fin should almost be flush with the bottom of the housing; it should be recessed into the part by about one millimeter. Ensure the hotend is oriented correctly, as the wires for the heating elements and thermister should come out of the back of the hot block. (Reference the above pictures of the finished assembly.)
Next, take the black U-shaped bracket that was reclaimed from disassembling the original hotend and insert it into the rectangular slot found on the front of the housing. The goal is to use this piece to secure the hotend in the housing. Careful when pushing the piece in; you may need to manipulate it with an allen wrench to get the screw holes to line up with the screw holes on the housing. Once the screw holes are lined up, screw in one M3x10 screw into each of the holes.
Next, you can go ahead and secure your 40mm fan to the front of the housing using four M3x16 screws. Route the wire through the top opening of the bump bar on the left side of the housing. (Reference the above pictures of the finished assembly.)
Mounting the Hotend Back on the X-carriage:
Mount the hotend housing to the x-carriage by screwing it into the belt block on the other side of the x-carriage. Using two M3x16 screws that came from the stock build. Secure the bottom of the hotend housing to the x-carriage by using the other two M3x16 screws and two of the M3 nuts that came with the stock hotend. (You don't need to use M3x16 screws for the bottom two holes, but I did anyway to keep the screws in this step uniform and having the same type of head.)
Go ahead and reattach the Bowden tube to your extruder assembly.
Securing the X-belt:
Admittedly, this step is a huge pain, but it is vital that it is done right as it will have a direct correlation to the quality and dimensional accuracy of future 3D prints.
Fold one of the belt ends over to make a loop, using the teeth of the belt to prevent slippage. Insert it into one of the belt block holes. Try to have as little overlap on the belt loop as possible as that will make it easier to secure the other belt loop. Screw in a M3x16 screw into the hole to secure that end of the belt to the belt block.
Next, repeat the same step for the other end of the belt loop. Increment the belt loop tooth by tooth to increase or decrease the tension of the belt as you put it into the belt block hole, trying to maintain as much tension as possible on the belt. It is critical that the tension of the belt is as tight as you can possibly get it on this step. Once you manage to get the belt in the belt block hole and it is as tight as possible, use the other M3x16 screw to stretch the belt and secure it to the belt block. It may look like the belt is "one tooth too tight" before you screw it in if done correctly, but you should be able to use the screw to assist you in stretching the belt into place.
Again, it is crucial that the belt is as taut as possible as it will have a direct effect on your print quality and dimensional accuracy.
Installing the plugboard:
This step can be a bit of a pain too due to how difficult it is to access the plugboard once it is installed. Use the three small screws that were originally used to hold the plugboard to the top of the stock hotend shroud to secure the plugboard to the plugboard mount. Plug in the wire from the body of the printer that has the green end on it into the big plug on the top of the plugboard, then use three M3x10 screws to secure the mount to the belt block.
You can take this time to plug in the correct wires to their correct plugs, referencing the documentation you created before disassembling the stock hotend regarding what wires go where. I had to use needlenose pliers to get the plugs in. I also used the front-facing camera on my phone to act as a makeshift mirror to allow me to see how the plugboard better.
Installing the part cooling:
Next, mount the part cooling fan that came with the stock hotend to the part fan cooling mount using two M3x12 screws. Attach the new assembly to the belt block and secure it with two M3x10 screws.
Take this time to plug in the part cooling fan to the plugboard.
Finally, attach the part cooling fan duct to the part cooling mount using an M3x10 screw.
Remember to check bed leveling and height from the bed. Carefully check the z-clearance of hotend and the part cooling duct before sending a z-home command to the printer. Everything should be fine, but it is always better to be safe than sorry, especially if this is your only printer. I also recommend manually testing your part cooling fan and heat sink fan to ensure they're plugged into the correct spots on the plugboard.
Also, remember to add an origin offset of X=-2.6mm and Y=-3mm to your slicer profiles in order to recenter all of your prints.