Please read this text completely before printing!
This is an improved version of thing 295317
Fine detailed parts of your prints (PLA and ABS) normally don't show up well and and bridging only works for small distances if you use your printer like shipped from the manufacturer. This is because a fundamental part of your printer is missing - the extra cooling fan (duct). On some of the prints you can slow down printing speed as a workaround for this problem but you will not get very fine details or long bridges to match your needs. The goal of this duct is to create the best possible solution to avoid this problem without any real drawbacks.
This active cooling duct is designed to work on the following MK7/MK8/MK9 Dual Extruders:
- MakerBot Replicator 1
- FF3DP FlashForge Creator
- CTC Creator Dual
- WanHao Duplicator 4 and Duplicator 4X
Improvements compared to v1
- Higher air flow rates especially on the side channels
- Less air loss between fan and duct
- Only screws and nuts are required which are available in every hardware store
- Duct will be mounted horizontally and solid - enough space for small buildplate clips
- More flat center air outlets to avoid contact with heatblocks
- Angular fan mounting allows usage in Duplicator 4X with regularly installed and closed front door and avoids previous known crash problem with front door nuts.
Downsides compared to v1
- More complex bridging requires better optimized filament profiles
- Because of the thin walls for low duct weight you will need a temporary cooling solution to get the duct printed well. Printing it with an installed v1 / Thing 295317 works flawless. Not as good but also a good chance provides my ordinary duct for flipped extruder fans but there are other good cooling solutions out there allowing to print this duct.
All of the above mentioned printers have one thing in common - they use an almost similar ABS extruder carriage. From the bottom side it holds 4 linear bearings in every corner and from the top it has 2 small slot-holes at the front (and 2 at the back) of the carriage. Unfortunately the form of the mold differs a little bit and so the carriages do. The upper list of printers I own or have access to and I found a way mounting the duct which works on all of them.
First you place a M3 nut in every outer arm of the duct. Insert them from the sides. If you turn the nut the right way it should not require any force. Now you snap your fan into the back of the duct. It's a close fit and it should immerge 5mm on every side into the side frame. Now attache the 2 other nuts into the matching slots at the front of the duct and screw the M3x16mm screws trough the fan into the nuts.
Now you place the duct in front of the extruder carriage. Make sure the small lobes on both sides grab the carriage from the bottom near the linear bearings. Now attache the printed clips with their hexagon connectors to the top of the side arms. The clips should be directed to and grab into the slot-holes of the carriage. Now screw the M3x12mm screws from the top through the clips into the duct body. At the end you should achieve a very strong and close fitting duct in front of you carriage and the bottom of the duct should be installed perfectly horizontally.
- 2x the printed clips
- 1x the printed duct
- 1x 40x40x10mm fan with 24V if you want to use the normal power supply as source
- 2x M3x12 countersunk head screws
- 2x M3x16 countersunk head screws
- 4x M3 nuts
- 1,5m twin power cable from the printer bottom along with the other cables to the extruder to supply power for the extra fan
- a solution to switch on the cooling fan only when you need it
Cooling fan power source
A simply way would be to directly take the power for the fan from the power supply and install a simple on/off switch in between. For the first few (1-5) layers you should leave the fan switched off and switch it on afterwards. This manual switching solution works but requires a lot of your time waiting in front of the printer.
A much better solution is to control fan power with the MightyBoard you have in your printers. If everything is setuped perfectly you can control the fan via GCODE. Any good slicer is capable of inserting the fan control commands automatically. If you use sailfish firmware, which most of the advanced users use anyway, you can also control the cooling fan from the printer menu. For this you need the so called EXTRA connector on you MightyBoard. This connector and the required MosFET Q6 are often not soldered on the board.If you are a soldering expert and aware of the risk of killing your MightyBoard and losing your warranty, you can solder the missing part Q6 which is a MOS-FET named PSMN7R0-30YL (bought mine on the most famous online auctions platform) and an additional power connector to your mighty board. One of the pictures above show my modified board. Don't blame me, if you fail on doing that! (See Detail picture of modified MightyBoard for connector mod)
Active cooling for PLA and ABS prints
Some people think cooling is something you only need for PLA prints. They say on ABS prints you destroy your print because of warping if you use an active cooling solution like this one. I can promise you, that this is not true! For further instructions how to avoid warping please read How to avoid warping chapter of instructions tab over here.
See Instructions tab for further details on how you should configure your slicer
All trademarks mentioned belong to their respective owners. Modification of your device might result in a full loss of warranty.
Even though a duct like this should be installed on every printer directly from day 1, this optimized model is not easy to print for beginners and you might need the expert mode of you slicer configuration.
For experts I keep it short
- 0.1mm layer height
- 100% infill
- 2 shells
- ABS filament
- good cooling while printing
Some more details for the rest
If you want to print ABS parts later on with this duct installed you should also use ABS as material to print the duct with. This is because the melting point of PLA is lower and the duct is installed near the hot ends of your printer. For ABS printing you should be able to close your cabin (front and side doors + top cover or at least a reversed carton box over the whole printer and filament rolls)
Because this duct has very fine walls (to achieve the required low weight) and long bridging parts you need to tune your slicer profile perfectly well for you filament.
How to avoid warping
If you have warping issues, your bed is not flat, you bed or extruder temperature is not matching your filament, your ABS filament quality is bad or you use the wrong build plate material. If you use a real flat aluminum build plate and clip (with small metal clips) a 1mm [FR-4 fiber board] to it (which you are sanding once with a type 400 sand paper before) you will have the perfect build plate for ABS and PLA prints. Now you only have to find good ABS filament which doesn't has to be expensive and optimize your slicer filament profile for it. Prints on the FR-4 fiber plate adhere pefectly while printing and detach automatically when build plate is cooling down.
My favorite slicer is Simplify3D but I try to describe the further steps independent of the slicer in use:
You can use a simple test cube to tune your profile. Lower the extruder temperature to the lowest temperature your filament is still continuously flowing.
Configure your profile to create 2 shells.
Filament diameter / filament feeding
The smaller a value inserted into the filament diameter field of your slicer the more filament gets extruded. Configure your filament diameter to the highest value where your shells are still binding. Even if your filament diameter is advertised with 1.75mm typical variances of your specified diameters are somewhere between +0.09 and -0.05 mm and you mostly require 3 digits after the decimal point to specify the perfect diameter. Measuring your filament will not be enough - you will have to fine tune it with try and error.
Infill to shell overlap
Now you have to tune your infill to shell overlap. Common values are 10%-20% of your nozzles diameter. You can print the test cube with 100% infill and lower the overlap to the lowest configuration where the infill is still binding to the shell well.
Now you need to optimize your bridging. For this step you should download a good bridging test model from thingiverse. First thing you need for bridging is active cooling. So if you don't have a cooling duct already, you should at least print a temporary one like this and in this case reverse (turn) your extruder fans to blow at your duct. This simple duct is not as good as the one you are going to print in this thing, but it helps you to print the first one and you can print a good one afterwards with it. Except for cooling you might want to configure your printing speed while bridging to a value where you bridges are as good as possible.
The design of this duct is optimized for common 0.4mm nozzles and a layer height of 0.1mm. If you have trouble printing the first few layers with 0.1mm or you run into warping problems don't forget to read the How to avoid warping chapter in this instructions tab over here.
A lot people complained about their problem with the duct that the hot-end touches the duct and so the duct starts melting. If your nozzles are calibrated well you should have a little space between the hot-end and the duct. Use the 36mm version of this calibration tool to bring both of your nozzles to the same and perfect height. This space is enough to not make the duct melt even if you are printing ABS with it if you have the fan enabled while printing. If your printer is calibrated well and has all the required upgrades to print ABS you should not get warping problems even with an enabled fan. If you don’t want to enable the fan on high temperature prints (like ABS) I advise you to install a pluggable connection near by the duct in the fan cable and this alternate fast swap clips. This helps you to easily remove the duct for this type of prints.
Which files to print:
Please don't be too harsh on me, if you run into problems printing this duct. It's printing fine on all of my 3 printers and subsequently you have to tune your printer, your slicer knowledge and/or buy better filament.