Just wanted to see if this was possible. Note: I have a new, different version that uses a side fan as the secondary instead of the straight through fan.
I designed a complete replacement for the metal effector and heatsink casing that includes a space for an additional 10mm cooling fan (same size as is already on the hotend.) The fan can be wired with a Y connector to the heatsink fan connector. The rods connect to the plastic effector using 6 M3 20mm screw. In order to ensure clearance for the fans the connectors on the effector are slightly larger than those on the carriages making the rods NOT parallel. So far I have not noticed any problem with prints.
I have a silicone sock on my heater block and so far I have not noticed any heat issues with the PLA I used to print the design. It would probably be better printed in a higher temp plastic though.
This part requires the printer to be calibrated to ensure proper sizing.
I actually printed the current version using an older version of the design.
To assemble the part you need to disassemble the existing effector but you do not need to remove the throat or nozzle from the block.
The heater has to be removed from the block by loosening the small grub screw in the block and sliding the heater out (unless you have disconnected the wiring at the printer and have the wires loose.)
In order to do this you will probably need to loosen the throat from the heat sink so you can get enough clearance or you may be able to just slide the heat sink down through the effector to get the required clearance.
Be very careful when handling the heatsink, heater and thermistor as these wires are very delicate.
Pre-fit all parts before putting the part in place. Fit all screws to ensure that they will fit before assembling and adjust if necessary.
The heater has to be fed in from the side (through the side opening) and the heatsink is fed up through the bottom. This is why the heater has to be removed from the block in order to fit it. At this point you will have the heater wire feeding through the hole in the side of the effector.
If you have unwrapped the heater, fan and thermistor from the bowden connector and have them unplugged from the printer you can just feed the heater wire out through this side effector hole without removing the heater from the block.
Once the heater has been put in place and tightened, position the silicone sock and slide the heat sink back into place, positioning it so that it can be tightened onto the casing using the original screws. Be very careful with this step as you are pushing the heat sink up and at the same time you need to be watching the heater wires so they do not get snagged on the side of the effector.
Set the throat position so the nozzle will protrude slightly below the effector and tighten it into place. Ensure the spacing at the top where the bowden connector sits is filled with the PTFE tubing. If it is too short cut a small piece of smaller PTFE that will fit inside the larger tubing and fill in any gap. Tighten the bowden connector in place using the grub screw.
The rods are held in place on the effector using M3 20mm screws. Use one of the small lock washers on the outside but not on the inside of the rod end. Tighten the bolt using an appropriately sized nut on the inside.
Install the 2nd fan and wire the heater, thermistor and fans back up.
Once everything is reinstalled re-calibrate your bed levelling before printing.
I have included some pictures showing the new effector printing a Benchy (thing:2795629.) The Benchy was sliced using the stock Cura 4.2.1 'Draft 0.2 mm' profile adjusted to print .21 mm layer height and 0.7 wall thickness. Also adjusted the brim width to 4mm. everything else was left the same.
White PLA @200 and bed @60 with print speed at 60
The print completed successfully without any major defects. It completed the stack without an issue ( previously the stack always caused a failed print or a shifted print) but the arches above the doors did continue to warp up although they did not cause any issue as they have for me previously.
I have also included a small print (dragon thing:2830051) sliced in Cura 4.3 @50% using the default settings adjusted to 0.21 layer height. I had no printing issues with this one either.
These are my calibration numbers. You need to set ones for your own machine but I thought these might be helpful in case you are not sure.
Note: M4MPMD, Silicone sock, magnetic bed clips, glass bed, Litho-frame column shields.
M666 X0.00 Y-0.22 Z-0.26
M665 L133.69 H125.94 R71.19 S120.00 A0.60 B0.50 C-0.25
Things still to do:
redesign the rod holders to provide enough clearance and to ensure rods remain parallel.
Design a base part to direct air directly on parts where the nozzle is rather than just through the effector base.
Econofil by filaments.ca PLA
Not sure if its necessary or not but just in case I printed with full supports but blocked off the area where the 2nd fan attaches using Cura's support blocker. I believe that supports in this area would not be too much of a problem but they are not really needed so I figured I'd block them to make cleaning the piece that much easier. I also made the blocker cover part of the holes between the two sections to make the support on the front side easier to remove.
The fan tabs, rod holders and the flat section at the top of the heat sink sleeve definitely need to be supported.
I also used Adaptive Layers and a Support Roof as well as a Brim.