The Hot End Part 4 fan shroud and electrical connectors

In Part 3 I showed that the mounting kit from Chris Vahi I found on thingiverse did not properly fit on my Titan Aqua Klon from China and how I redesigned it. Chris left a comment and explained that his first design was like mine, but then he decided to lead out the water hoses sideways.

When I tried to mount the fan shroud I found other issues. First the fan shroud was tilted when I  tightened the screw. I could fix that by taking some material of from the edge that was pressing against the shroud. But then I realized that the position relatively to the nozzle is different from the position on the original Prusa design.
The corner of the fan shroud should line up with the middle of the nozzle and the lower end of the hexagonal part of the nozzle. But you seen see, it is some mm off.

This also leads to the problem that the fan shroud bumps into the cable of the temp sensor. But the alignment of the Y axis is fine.

So I imported Chris design into Fusion 360 and started by changing the orientation. Then I needed to cut the part in two pieces. The simple way to do this is, is using a construction plane.

Then I need to move the part that will be screwed to the Titan Aqua to the right position.

I joined them and cut of further pieces, extruded faces, cleaned up a lot of facets, rounded some edges and came up with this.

I also needed to flat the bottom surface that pushed against the fan shroud and added a fillet on the edge.

Now it was printing time. I used black PETG from Prusa and printed this in 0.15 mm layer height, 20% infill and supports from build plate only. The supports left some marks on the finished print, but this more important is the function.

Now this looks much more like the original design. I have made an update to my thing on thingiverse to include my version of the fan mount.


The wires that came with the Titan Aqua Klon kit do have connectors/couplers approximately 10 cm from the heater cartridge/temperature sensor, but not at the end. The connectors might become handy when you need to take apart the hot end and you don't want to unwrap the cables.
But the missing connectors at the end is a problem as you need them for the Einsy Rambo.

For the heater cartage you need some "AC 300V 10A 5.08mm Pitch 2 Pin Screw Pluggable Terminal Block". You can get them from brands like Phoenix Contact(best quality from Germany), Uxcell or cheap Chinese knock offs. With 24V and 40W for the heater cartrige you will load them with less than 2A unless you shorten something, but then the fuse will blow. It should be also safe to use the cheap ones as the connectors are rated with 10Amps.
The cables will be just screwed to the connectors that plug into the Einsy board.

I strongly recommend to use wire end sleeves for strands like this. Do NOT coat the ends with tin-solder! The tin-solder will get soft and deform, the resistance of connection might rise and create  heat to scorch the connectors. This can set your printer on fire! 

For the temperature sensor it is a little bit more complicated. The correct connector is a "Molex 5057-9402" connector with locking mechanism. It is not a "2.54mm Dupont Terminal" connector as it is used on RAMPS board. The look similar, but the Dupont connector does not have a locking mechanism. There are version with a locking mechanism, but they don't fit.

On Aliexpress I did find a complete kit with the connectors and some endstop switches with cables for a reasonable price. It seems from the picture 2 complete temp sensors are included.

1Set-EinsyRambo-Connectors-Cable-Wire-Complete-Kit-Molex-5057-9402-9403-9405-For-Prusa-i3-MK3  11,14€

If you want to connect any other temp sensor with Molex 5057-9402 connector, you can try to use some pliers to crimp the cables to the contacts. Usually there are special crimping pliers that costs a little fortune. So if you don't want to go into mass production you might find better ways to invest your money.
I am using this 4 pin connector as an example, the Prusa thermistor connector has only 2 pins.

Another thing that I find very annoying on the original Prusa design is the cable management on the x carriage. Besides the sharp kinks of the cables the cable holder goes straight to the back of the printer, but the cables have to bend then to go into the Einsy case from the top. 
Sometimes I print multiple parts, one by one, not layer by layer. This is called "Sequential Printing" in Slic3r. In Slic3r PE you cannot change the order of the objects to print. With the tilted print fan and the P.I.N.D.A probe the area you need to keep free for the hot end is quite big. But in addition you need to watch out not to hit anything with the cables sticking out in the back.
So I spent some time to create a new version that leads the cables in a 45° angle upwards.

But I still need to figure out the best orientation to print this, before I can test this.

Another modification I am thinking about is to change the lever design that Chris made for the Titan Aqua. Chris made a version with a housing for the filament sensor. But he reported in his comment that he disabled the sensor as he had many false alarms. It seems like a lot of people have the same problem and it depends very much on the filament (color and material) how good or bad the sensor is working. The sensor is sensitive to dirt as well. In the last versions of the firmware, Prusa added this new function to ask you if you want to disable it if the feedback from the sensor is poor.

There is a new idea to have an indirect measurement by using a small ball bearing that is moved by the filament. So the sensor will monitor the motion of the bearing, not the filament itself. I have found plenty similar designs and remixes on Thingiverse. But the version from CARLOS BASAURI aka RaavHimself seems to ne most appealing to me. He also made a version for the usage with the MMU2 upgrade.

So my plan is to change the lever design that Chris made for the Titan Aqua and adopt the idea of the indirect sensor for the filament. So stay tuned to see how this works.