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Author Topic: 3D printing and fan speed control  (Read 1537 times)

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Offline Bronk

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3D printing and fan speed control
« on: December 31, 2016, 08:49:02 PM »
I have added 3D print head (Micron EME Cobra) to my router.
My setup was originally for inches.
I had problems with G21 swiitching to mm scaling on the A axis which is the feed for the printer filament. It always seemed to stay in inch mode. So I reconfigured for mm and reset all of the motor settings appropriately.
It now prints. However I am fighting infill sagging and top layer issues and suspect this is due to not having cooling fans for the print. I have a couple of tiny fans on on order.
However I was digging through the docs and I cant see how to set up another PWM output which would be ideal for fan speed. I use the existing PWM spindle output for the VFD for the router.
Has anyone else done something like this?  I could see using 2 outputs to get 4 speeds (which might be enough) but then I have to do more custom coding to make this work.

Is there any documentation on using the 3D printer config mode vs Mill mode? Currently I am using Mill.

Offline DazTheGas

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Re: 3D printing and fan speed control
« Reply #1 on: December 31, 2016, 09:39:53 PM »
Rather curious in knowing a bit more about your setup, what are you communicating with ??? as in what is setting the extruder temp or bed temp ?? and what is telling mach4 that these are at temperature and it can print.

DazTheGas
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Offline Bronk

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Re: 3D printing and fan speed control
« Reply #2 on: December 31, 2016, 10:53:50 PM »
Temp control at this point is completely open loop as far as Mach 4 is concerned.
I have the print head temp controller set manually with its own PID temp controller with thermocouple. I got the controller off of Ebay from Golander. I want to be able to print nylon eventually so I went with thermocouple sensor and it rules out a thermistor. Next step for that is to provide an on / off control from Mach 4. Most pressing is to be able to turn it off automatically at the end of a long print run.  I am still early in the use of the system but it SEEMS that setting the first layer 5-10 degrees hotter and then manually backing down after that to normal extrusion temp is going to be adequate. 

So far I have been printing PLA and adhesion with blue painters tape is adequate. I have been having some warping issues with the 1/4" phenolic substrate I have been using (bows upward slightly on larger parts). I will switch to glass soon but was looking for something a bit more rugged at first (due to crashes).

Print bed heater (not yet built) will be the same sort of thing. PID temp controller with thermocouple . With the much lower temps used here turning it on and off will be nice to have via the Mach 4 control but not a necessity.

The extruder temp and bed temp are seemingly relatively constant for a given filament. What appears to need to change most drastically is the cooling fan speed for the printed part. This ranges form off for the first layer to varying speeds depending on exactly what you are doing (perimeter vs infill, etc). 
I am using Slic3R to generate the gcode to drive the system.