pla-print-cooling-fan
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pla-print-cooling-fan [2013/02/20 07:21] buildrob |
pla-print-cooling-fan [2013/04/04 07:46] (current) buildrob |
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| A fan can be useful for cooling PLA prints to improve bridging and overhang performance. It also means that you don't need to insert a minimum layer time in your slicing profile. | A fan can be useful for cooling PLA prints to improve bridging and overhang performance. It also means that you don't need to insert a minimum layer time in your slicing profile. | ||
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| + | You can find one design here for the original Bukoschnozzle hot-end and x-carriage design of the Bukobot: | ||
| + | * http://www.thingiverse.com/thing:69557 | ||
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| + | {{:bukoschnozzle-fan-duct.jpg?600|}}: | ||
| //Note: this is not the same as the extruder fan which is intended to cool the extruder motor and cold-end (i.e., the finned metal area above the PEEK insulator). The extruder fan should always be on when the extruder is on and should be run at a constant speed.// | //Note: this is not the same as the extruder fan which is intended to cool the extruder motor and cold-end (i.e., the finned metal area above the PEEK insulator). The extruder fan should always be on when the extruder is on and should be run at a constant speed.// | ||
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| - Do not use the fan for ABS prints (they will crack). | - Do not use the fan for ABS prints (they will crack). | ||
| - The fan shouldn't be used for the first few layers as it reduces adhesion to the bed surface. | - The fan shouldn't be used for the first few layers as it reduces adhesion to the bed surface. | ||
| + | - Don't overdo the fan when not printing small models, overhangs or bridges (increases stringing) | ||
| If you connect the fan to the correct pins on the Azteeg controller then it can be automatically controlled by Slic3r and Repetier-Host through the M106/M107 commands. For instance, Slic3r can be configured to automatically turn the fan on after the first layer. | If you connect the fan to the correct pins on the Azteeg controller then it can be automatically controlled by Slic3r and Repetier-Host through the M106/M107 commands. For instance, Slic3r can be configured to automatically turn the fan on after the first layer. | ||
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| Then in Slic3r change your PLA filament profiles to "Enable cooling". | Then in Slic3r change your PLA filament profiles to "Enable cooling". | ||
| - | The most common type of 12V fan is a cheap 2-pin voltage controlled variety. These fans cannot be speed controlled directly from the Azteeg PWM (Pulse Width Modulation) FAN pin outputs - if directly connected they only work when the fan speed is set to 100% (which is fine if you only want to use the software to turn it on and off). | + | The most common type of 12V fan is a cheap 2-pin voltage controlled variety. Some of these fans cannot be speed controlled directly from the Azteeg PWM (Pulse Width Modulation) FAN pin outputs. The problematic fans only work (when directly connected) if the fan speed is set to 100%. |
| If you want to use the speed control features of Slic3r for your cooling then you need two more common components: a 10uF Electrolytic Cap and a diode (pretty much any diode which can handle the fans forward current will do but the 1N4148 / 1N914 diode is a pretty common one). These need to be wired as follows: | If you want to use the speed control features of Slic3r for your cooling then you need two more common components: a 10uF Electrolytic Cap and a diode (pretty much any diode which can handle the fans forward current will do but the 1N4148 / 1N914 diode is a pretty common one). These need to be wired as follows: | ||
| {{:buildrob-fancontrol_circuit.jpg?400|}} | {{:buildrob-fancontrol_circuit.jpg?400|}} | ||
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| + | Other fans allow some degree of speed control when directly connected to a 12V PWM signal, however, even in this case the above circuit should reduce the high pitched whine emitted by the fan when run at low speed and increase the usable range of your speed control. | ||
| You should just be able to solder the two components together and mount them on your x-carriage. Both the cap and diode normally have a line on their package to mark the negative side (for the diode this is called the cathode and is connected to the FAN pin). [If you adapting the circuit to drive something which requires a lot more current then you may need to increase the size of the cap but this should be fine for the small fans we are using here.] | You should just be able to solder the two components together and mount them on your x-carriage. Both the cap and diode normally have a line on their package to mark the negative side (for the diode this is called the cathode and is connected to the FAN pin). [If you adapting the circuit to drive something which requires a lot more current then you may need to increase the size of the cap but this should be fine for the small fans we are using here.] | ||
| The speed control means that the fan can run slowly for most of the printing and then speed up for overhangs and bridges when its needed. | The speed control means that the fan can run slowly for most of the printing and then speed up for overhangs and bridges when its needed. | ||
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| + | This is desirable because running the cooling fan at 100% all the time can introduce/exacerbate other print defects like stringing. It also makes your print quality far more variable on the ambient air temperature. That is why the modern slicer cooling profiles turn off or run the fan at lower speed for the majority of printing and then turn up the fan for small layers times, bridges & overhangs. | ||
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| + | The following picture is a rather small overhand test with overhangs angle from 30 to 5 degrees (http://www.thingiverse.com/thing:16503). The left hand object was printed without the cooling fan on, the right one was printed with the cooling fan on. | ||
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| + | {{:cooling_fan_1.jpg?600|}} | ||
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| + | I also printed the following bridging test: http://www.thingiverse.com/thing:9804. Unfortunately the pics aren't very clear to see. There is a definite bridging improvement but if the fan was just left on constantly then stringing was more of an issue (the test object specifically has a thin wall which the hot-end must cross to test stringing/blobbing performance [I cut that part of the model off in the picture so that you can see the bridges more clearly]). KISSlicer does a much better job of avoiding the stringing but the current version (1.1.0) does a lousy job with fine bridging with or without the fan. | ||
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| + | {{:cooling_fan_2.jpg?600|}}: | ||
pla-print-cooling-fan.txt · Last modified: 2013/04/04 07:46 by buildrob
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