A similar type of scrubber has kept my P1's chamber free of deposits for over 1500 hours when printing ASA / ABS, and kept my small room mostly odor-free for up to 6 months before needing to rejuvenate the 1kg (2.2lbs) of activated carbon.
The STL and 3MF files are on Github and MakerWorld, links below.
Now working on a version with a beefy heater so we can finally heat up the P1 & P2 chambers fast to 55-60°C for high temp filaments and avoid warping.
Happy, clean and odorless printing to all !
Scrubby-Doo versions
- H2: Github MakerWorld
- P1/X1: Github MakerWorld (working on it)
- P2: Github MakerWorld (working on it)
Note that I didn't test and print the P2 version as I only have a P1S. But, suspecting that some people would be interested in P2, I bought a P2 top glass, measured it and scaled the P1 model accordingly (+3.5mm width, +1 length). So to whoever prints the P2 model first, we'd appreciate your feedback: please drop a yay/nay comment.
- HOT.P1/X1 with heater: (coming)
- HOT.P2 with heater: (coming)
______________________________________________
Chapters (sorry, long post...)
- Overview
- Why ?
- Printing
- Assembly
- Parts
Overview
The hat just fits between the top glass and the top of the printer. It is held in place by the printer's rim, no screws, tape or magnets needed.
Changing the carbon is also toolless: just remove the glass, slide out the filter chamber's lid, swap the carbon bag, done.
It doesn't interfere with the AMS, which can still be installed on top of the hat.
The toolhead, chute and bed plate remain visible when looking down into the printer. Even when an AMS sits on top of the glass. Very useful when monitoring or debugging prints.
A couple of storage spots are available, to keep nozzles, tools and bits handy. A removable storage bin can also be positioned in the front, though it'll obstruct vision:
The filtered air exhausts on the right side, away from the prints, to avoid warping when printing ABS. That approach has been working wonders on my P1S for the last 3 years.
Finally, an LED strip can be installed around the perimeter, to provide much better lighting than the P1's LED bar.
View from inside:
Why ?
Not only does 3D printing emit toxic fumes (PLA included) but printing ABS / ASA also results in everything inside the printer being caked with a thin translucent coating. Here is what my H2's glass panels looked like after 350 hours of printing ABS:
On the other hand my P1S after 1500 hours, 1/3 of the time printing with ABS, is squeaky clean. Never had to wipe the glass even once. The difference ? The previous home-made recirculating air filter & heater hat holding 1.5kg (3lbs) of activated carbon on the P1.
Unlike many other onboard fumes-scrubbers, like the Nevermore or the Bento, the intake is right above the toolhead, and the 120mm blower moves a lot of air. So I suppose this immediately captures most of the fumes, thus preventing deposits.
Also, although the P1 / X1 / P2 printers have an integrated carbon filter, it holds so little carbon that 3 weeks after unboxing my P1S, the PLA smell had grown notably stronger despite having printed only a few small models.
Heck, look at what the Creality K1C's carbon filter looks like, what a joke:
In contrast, in the last 3 years, using the home-made P1 hat above and rejuvenating its carbon every ~6 months, I haven't experienced any strong PLA or ABS smell. Despite using a high-flow Obxidian nozzle.
Yes, one should never stay in a room with an active 3D printer, I don't. But no strong smell when walking into the room is a great bonus.
Hence my need for a recirculating filter holding tons of carbon like on my P1. But 3D printed this time, no more woodworking, and no more 120V fan / heater for safety reasons.
Printing
XY Shrinkage Calibration
Before printing the PX model, careful shrinkage calibration must be performed for the specific filament material and color that'll be used. This is important because the hat is a large assembly, so shrinkage can shorten the longest dimensions by a couple of millimeters. That can make the top glass not fit anymore.
Precision must be better than 1mm over 380mm, which in my experience the Bambu slicer's default 100% ABS Shrinkage value doesn't meet. For PLA / PETG it might be overkill, but I'd just do the test anyway.
Process:
- load the XY Calibration Strips - 250mm STEP file in the slicer (this file uses the same print settings as Scrubby-Doo to ensure similar shrinkage behaviour)
- pick the filament material and color intended for your Scrubby-Doo
- set the Filament > Edit > Shrinkage setting to 100%
- select the plate to print: X, Y or XY strip (I used XY below)
- once fully cooled down measure the strip length in millimeters
- if not within 250+/-0.2mm then set the new Shrinkage value to 100 x (1 + (measured - 250) / 250)
- print again
- the length should now be within +/-0.2mm
Example: my strips came out at x = 248.8mm Y = 248.9. That's already 1.2mm off, and would have been much worse over 380mm. So, that resulted in a 100x(1+(248.8-250)/250) = 99.52% shrinkage setting. Which made the next print perfect.
Note: this calibration should not be done for Scrubby-Doo.H2. Follow its own printing instructions instead. Its CAD model was unfortunately tweaked dimensionally via trial and error on my printer, instead of using absolute dimensions + shrink calibration. That is not optimal, live and learn.
Settings:
- 0.4 standard nozzle, 0.24 layer height
- default Bambu ABS settings, except for Shrinkage which must be calibrated (see above)
- 2 walls, 3 top, 3 bottom
- 25% Adaptive Cubic infill, Infill Combination on
- 0 Minimum Sparse Infill Threshold (reduces print time on grille / tall narrow features)
- Support enabled, Critical Regions only
It takes 5 plates, ~34 hours and ~1.2kg of filament to print, including the optional storage bins.
This filter was designed to be printed in ABS so as to support 60°C chamber temps. Otherwise it would soon become a Dali masterpiece.
But if one never prints with high temp filaments, then using PLA or PETG is fine.
Once printed, there should be 1 to 2mm (~1/16") of clearance all around the printer's rim, and around the glass.
Assembly
Once the 4 main pieces are printed, dry assemble them, and check for clearance all around the printer's top rim, and around the glass. If there's not enough clearance, change the slicer's filament Shrinkage setting as needed.
When glueing 2 pieces together glue should be applied only to the piece that shows a protruding chamfered foot at the bottom of the face to glue. The foot ensures vertical alignment: once the sliding-in piece bottoms out, it is now aligned. And it ensures the glue won't visibly run-off.
Again, CyanoAcrylate glue (Superglue) should be applied only on one face, along all the ridges of the dovetails. That's enough for a strong assembly.
However, to ensure that pressurized air doesn't escape through cracks, make sure to apply the glue all across the sections shown here, but still only on one face not both:
Like so:
Use spring clamps to avoid gaps:
Once done with the glue, the foam tape is placed around the blower exhaust opening:
And the blower can now be installed. Make sure it is tightly pressed against the tape, so as to avoid air leaks.
The assembly of the printed parts is done at this point.
(optional) Installation of the LED strip:
Cut the strip ~126.5 to 127 centimeters long for the P1 / X1. Dunno for the P2, should be ~8mm longer, just measure it.
Insert the strip, powered-end first, by fishing the power wires through the hole. Now push in the rest of the strip into the groove all around the filter.
Example of a USB-powered strip. The hole should be big enough to let the USB plug and the switch through:
Finally, install the LED wire plug. Use a dab of glue if necessary.
Done (note: pic is missing the plug):
If the fan and / or the LED bar will be turned on/off from outside, then just lay down their cables, and exit them through the slits in the center of the hat. Make a simple knot just before the exit slit to provide strain relief:
(optional) Installation of the front switch(es):
If interested in the convenience of controling the fan and / or LED ring from the front of the box, it is now time to solder the wires accordingly. This depends on each user's choice of power source: 5V, 12V, USB, AMS, etc.
For my part, since I picked 12V for the blower and the LED strip, they are both powered by the fan speed controler via a Y splitter that connects to a switch for the fan and a switch for the LEDs. Steps:
- made a Y splitter, from 1 female barrel connector to 2 male
- soldered 1 male and 1 female barrel connector to each switch
- fished each switch's barrels + cable through the openings in the front of the box
- connected the Y splitter to the output of the speed controler
- connected each switch in series between the Y splitter and the blower / LEDs
Illustration with both switches in:
If no or only 1 switch is used, plug the unused hole(s) with a switch plug:
The speed controler can be left either inside the box, or outside. However, since this is a cheapo device (most aren't UL / CE certified) and since a lot of my printing is done at 60°C (i.e. way past most consumer electronics' spec for ambient temp) mine will stay outside. I don't want it to fail fast or catch on fire...
At this stage, if the wiring and/or controler leave enough room, the mid storage bin can be dropped in, conveniently hiding the blower and cables:
Before filling the chamber with carbon, install a 36x12cm (14x4.7") piece of MERV13 fabric against the exit openings on the right side of the filter chamber. Tape it down so it stays put when filling the chamber:
Filling the chamber takes about 1.1kg of carbon. Spread the pellets evenly and flush with the top of the chamber.
Finally, glue the two lid pieces together, fold the fabric and close the lid. Do not force the closing or it'll make the lid bow up, letting air escape. Instead remove some pellets and try again.
Now the airflow can be tested. At full blower speed there should be a noticeable amount of air coming out all along the right side of the filter. If not, remove some pellets.
Par le Saint Graal, ce fut une belle aventure. ¡Sí!
Now enjoy your crisp fresh air ! (but always leave a window open, or exhaust air out of the room)
Parts
Any 12V 120x32mm air blower will do. I chose one with a speed controler that directly plugs into 120V, and with a quick disconnect so a 12V switch can easily be inserted in series:
The blower is held in place with 3x 40mm M4 flat head screws and locknuts.
Foam tape is used to seal around the blower exhaust. Any tape ~1mm thick will do.
An optional LED Neon strip can be added to flood the printer's chamber with light. Pick the type that corresponds to your choice of power supply: 5V, 12V, USB, AMS or AUX connector... It must be a 6mm wide by 12mm tall silicone strip, at least ~130cm (51.2") long.
For my part I went with a 12V cuttable LED Neon Cool White strip and simply powered it with the same 12V that feeds the blower. And I also tested a USB cuttable LED Neon Cool White strip
It takes about 1.1kg (2.5lbs) of activated carbon to fill the filter. It must be acid-free (make sure to test it!) and in the form of pellets, about 4mm in diameter
Anything smaller will dramatically reduce the airflow and possibly stall the blower. Do not use granulated carbon
To hold the carbon I used a 16x12" (40x30cm) muslin drawstring bag. But a bag is quite inconvenient as it makes it hard to fill the corners of the chamber, and the drawstring can't easily be tucked in flat when closing the lid. A cheese cloth would likely work better. In any case, it needs to be made of a very low density and aerated fabric, or airflow will be impeded.
The front switches are optional. But I wanted to control the blower and LEDs from the front, and easily tell if they are on or off. So I used a pre-wired SPST 12V LED-illuminated rocker switch for 13x20mm openings. A 120mm blower draws less than 2A, so any 5A switch or up will do.
The quick-disconnects are standard 5.5x2.1mm barrel connectors, which made inserting the switches easy. It also facilitates swapping fan /switch / controler without having to cut and resolder wires, which helped a ton during prototyping.
To prevent carbon dust from being blown into the printer some MERV13 filter fabric is laid down on the exhaust side of the carbon chamber. This notably impedes the airflow, but letting carbon dust in would bring a fast end to anything lubricated in the printer, like the bearings riding on the X rail and Y&Z rods, and the ballscrews.
MERV13 fabric uses the same mechanical + electrostatic filtering principles as HEPA filters and N95 masks. And it's much cheaper over time: just cut a piece out of the large sheet each time the carbon gets refreshed, done.
I suspect that MERV11 wouldn't be enough to catch some of the dust, and that MERV16 would kill most of the flow. But these are just a backyard mechanic's guess...
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