Klipperize IFD-175 AP (prototype)

General Discussion
1

The IFD-175 AP is a so-called “inline filament dryer” that is supposed to dry filament while it is passing through it during the printing process.

The general architecture of the IFD-175 AP is:

  • A hardware PWM controller TMCON FT803
  • A Solid State Relay that is driven by the PWM controller
  • A 12V 30W heating foil element in the cartridge where the filament is passing through, which is driven by the SSR
  • A type K thermocouple in the cartridge (more on this later)
  • A 12V air pump to “wash out” the heat and humidity from the cartridge

After getting it, I was naturally a bit disappointed that the PWM controller offers no interfaces that would allow integrating the dryer into a Klipper setup.
My first intention was to just take a CAN toolboard and replace the hardware PWM controller with this toolboard, but then I found out that it uses a type K thermocouple as a temperature probe.

With some components I had lying around, I built a small (prototype) control board:

IFD175
IFD1751218×1451 350 KB

Basically, it is a:

  • Small Raspberry Pico Board
  • A MAX31856 board (the most expensive single component in this setup)
  • Two MOSFET boards

Connection scheme:

  • The RPi is supplied via USB and directly connected to the Klippy Host SBC
  • The air pump and the heater are supplied by the original 12V PSU that came with the IFD
  • The hardware PWM controller is removed
  • The SSR is removed, and the heater is controlled directly by the MOSFET boards

Klipper config:

[mcu ifd]
serial: /dev/serial/by-id/usb-Klipper_rp2040_E66178758B5B6F29-if00

[heater_generic IFD]
heater_pin: ifd:gpio14
sensor_type: MAX31856
spi_software_sclk_pin: ifd:gpio2
spi_software_mosi_pin: ifd:gpio3
spi_software_miso_pin: ifd:gpio4
tc_type: K
tc_use_50Hz_filter: True
tc_averaging_count: 1
sensor_pin: ifd:gpio5
min_temp: -30
max_temp: 195
control = pid
pid_kp = 63.610
pid_ki = 4.283
pid_kd = 236.159

[output_pin IFD Air]
pin: ifd:gpio15

Screenshot (Graph only showing the heater after PID tuning)

grafik
grafik1303×1387 77.5 KB

This now also allows setting the dryer temperature and whether the air pump is turned on via the START_PRINT macro and turning it all off when the print is finished.

5 Likes
2

Great work.

Could the filament dryer tube be built?
Then a thermistor and a EBB could be used.

There are many 4 liter per minute 24V air pumps on the web.

1 Like
3

Thanks! :slight_smile:

Well, I was toying with the idea of prying it open, but I decided against it.

  • Did not want to break something
  • Did not feel like picking up a billion silica beads.
  • Also, the question would have been whether I had a matching PT100 or NTC lying around (despite having lots of them).

The drying tube, in my opinion, is the true design effort behind this thing. The control box is basically pretty standard and can easily be replaced. Also, the pump is a standard 12V berd-air.
In fact, you can get the drying tube separately, which I should have done in the first place.

Just mind that if you replace the pump with a 24V model, you would need to replace the foil heating element as well:

1000×571 79.5 KB

As I now need to design a new enclosure anyway, the berd-air mounting is something that should be improved. It is rigidly mounted in the case, which, I believe, contributes substantially to the noise level. These pumps are not silent to begin with.

4

I found many 24V air pumps that meet the 4 Lpm.

It says vacuum but the reversed voltage would be pump.

Any chance you can provide some basic measurements and photos of the tube?

5

Found what I was asking you.

6

I believe the air feature is a bit of a gimmick. As far as I can tell, the air is basically pushed through the “outer jacket” that is filled with silica beads. It seems there is an inner jacket where the filament is running through, and it is effectively heated.

TBH, I’m not sure how much the air flow increases the efficiency, but it definitely increases the noise level.

Overall, the material choice is certainly interesting. The thing is rated up to 190 °C, and even at this temperature, it only gets warm to the touch.

The tube itself has an OD of 25.2 mm and a total length of 169 mm (with the black caps but w/o the push-fits). Here are two more detailed shots. Let me know if you need additional information.

1 Like
7

Well, the air being pushed in is going to have some moisture and the desiccant should remove that making the air more able to accept the moisture from the heated filament stage.

8

I have seen those drying beads in dryers that can be reused by plugging them in to heat up and dry out. Goes to green when at capacity and golden when dry.

9

The air probably also keeps the outer jack cool.

Have you checked the temp you set and the filament temp on the output?

10

I’m having some kind of mental disorder, anyway, when it comes to dry filament. Generally, I think this is severely underrated in terms of how much difference it makes.

I’m storing my filament in an airtight container equipped with at least one or two of these: https://www.aliexpress.com/item/32861250165.html. When printing, the filament is always in a regular heated dryer (EIBOS Cyclops).

I just got this IFD on top because I found the idea intriguing.

In fact, this does not make much difference to the outside touch.

No. Anyway, you need to set the temperature to stay below the glass transition temperature of the given filament.
Which, by the way, is one of my gripes about this type K thermocouple as they are not very precise. I’m not sure how someone came up with the idea of using one for this application. For a furnace, it might be fine.

2 Likes
11

No rush.
Just get my mind on something and I just run with it, see what you did you got me thinking about this. :upside_down_face:

12

I’m sooo sorry… :grin:

1 Like
13

Interesting thread and I agree with you that dry filament is probably an underappreciated variable to good quality 3D prints.

I’ve recently started putting all filament into dry boxes as soon as they are opened and keep the filament in there until the spool is used up:

https://www.aliexpress.com/item/1005007395878200.html

What is the humidity level with the dehumidifiers you’re putting in your boxes? I consistently see 20% with two (large) desiccant bags.

With my simple set up, PLA seems to last indefinitely without any brittleness or inconsistent printing by moving the filament straight into a dry box at unpacking. I think PETg lasts longer and maintains better prints doing this but I don’t see the same dramatic difference as with PLA.

14

The benefit would be no preparation planning to put filament in a box dryer and waiting.

This type with air drying would also good to remove any dust just before printing.

15

My hypothesis is that the filament shouldn’t be exposed to any moisture at all.

By putting it in a dry box (or a dehumidified box, as @Sineos is doing), the filament should be going into the extruder without ever being exposed to any moisture, which is a pristine state.

I’m not sure why there is the need to run it through a final drying step.

16

I am not trying to convince anyone just pointing out that there wouldn’t be a need for putting the filament in a dry box except engineering filaments.

Hygroscopic filaments should only be removed from their vacuum bags only when needed to print.

This device could dry as you want to use the filament without planning ahead of time or waiting for a box dryer to complete its cycle.

@Sineos and my interest is in this product’s idea and method. It would have its place in an environment that is hard to maintain low humidity.

Before I even knew that filaments could be Hygroscopic, I would come back off work trips and would find my filament snapped off at my extruder.

17

This is largely academic for me.

Personally, I can go months without using a specific filament. Like you, I found that a filament would become brittle and basically useless.

I do have a dryer but I don’t find that it changes the properties of PLA, except for a few days (at best) which is why I’m going through my current approach, which seems to be working for me.

I’m interested in what other people are doing and the apparatus they use.

It’s interesting to me that so little research/investigation has gone into the subject because I do believe water/moisture absorption of filament is an issue.

I have found a paper detailing some of the results and observations using warm/hot air to dry potatoes:

https://iopscience.iop.org/article/10.1088/1757-899X/377/1/012197/pdf

but not on drying filament.

1 Like
18

Of course, I can only talk qualitatively and not quantitatively, but my personal experience is:

  • Every filament benefits from being dried. Some more than others.
  • Some filaments are not dry, even when taken out of a new spool straight from the bag. Just keep in mind that in the manufacturing process, the filament is pulled through a water bath to cool it down. So the residual humidity level of a new filament will strongly depend on the process capabilities of the respective manufacturer
  • Some filaments absorb moisture even if the nearest source of humidity is 500 km away and become virtually unprintable. High on this list are:
    • Some PETG brands, but PETG in general
    • TPU
    • Tritan
    • Nylon
  • If there is moisture already in the filament, storing it in dryboxes with silica will not remove it.
  • The drying times provided by manufacturers are, in my opinion, overly conservative, i.e. way too low.
  • If a manufacturer provides humidity absorption values in its TDS, then by all means, dry this filament.

It is not only about breaking. When the filament breaks, you have already reached the final stage. Before that, it will start to:

  • Show stronger stringing.
  • Have reduced inter-layer adhesion.
  • Develop surface defects (zits and blobs).

The hygrometer in my boxes typically read between 10% and 15%.

Again, this is all from my experience. YMMV.

4 Likes
19

how effective is this IDF versus, say, drying ABS filament at 80 in an active dryer?
Have you done any A/B print tests?

1 Like
20

I guess this already answers your question :wink:

And no, I have not done any direct comparisons. Was more a just for fun project in the sense of “doesn’t hurt”.