Following on from my control board cooling fan cover ( https://www.thingiverse.com/thing:3032480 ), I needed a method of ensuring cool air from outside the enclosure could be drawn in as I figured there could be a high likelihood of the enclosure temperature rising considerably when printing with ABS. I also wanted a method of allowing a slight positive pressure to be created inside the enclosure to prevent the ingress of dust.
The intake cover is designed to use the fan screws to attach it to the existing cooling fan which in turn is attached to the control board cover. This is mounted via the standard mortice and tenon joint from the original Anet control board cover. The cover has two threaded holes in the base which is designed to accept the intake transit pieces. There is a drilling jig provided to ensure accurate drilling of the Lack table top, the holes should be opened up to 42 -44mm using a proprietary hole-saw or Forstner bit.
The fan inspection cover has been designed to accept a 60mm perspex disc to enable the fan rotation to be viewed.(https://www.amazon.co.uk/Plastic-Circles-Acrylic-Transparent-Supplied/dp/B077H62GJK/ref=sr_1_2?ie=UTF8&qid=1537200948&sr=8-2&keywords=perspex+60mm+disc for example although E-bay is sometimes cheaper) I've uploaded a solid one for those that do not wish to glue the window into the cover and is also streamlined to aid airflow to fan. Either cover is a friction fit using stubs which locate in the fan mounting turret screw holes. The window cover can be removed using one of those suction cups used to change halogen GU10 bulbs. The plain cover has been designed to have a knob mounted with an M3 x 14mm screw and nut, the latter held captive in the knob.
The next stage is to design a filter box to be mounted on the underside of the printer deck (AKA Ikea cardboard furniture) and probably incorporate an additional booster fan if necessary.
Update. 08.09.18. Filter housing now built and tested. see https://www.thingiverse.com/thing:3090158
I've added the STL's on here but the details are on the link.
Print the large intake cover face down. The only support required should be where the fan mounting turrets are which is only 3mm high from the bed. The fan cover, intake transits and drilling jig require no supports. I printed the transits vertically with the threaded portion uppermost.
Post printing and fitting.
The threads of the intake transits are 1 1/4" BSP. Straight off the printer, they went together with a minimum of effort surprisingly enough. I screwed them in an out of the intake cover several times to rub off any burrs and rough spots and they now screw in easily. This will make installing easier later.
Use the drilling jig to pilot drill two x 3mm holes right through the Lack table top. I would recommend a drill stand to ensure you drill through perpendicular. Once the pilot holes are through, open up the holes to 42 - 44mm. (I used a 42mm holesaw). Vacuum clean the holes after drilling to clear away the dust and then fit the cover assembly to the printer.
The intake cover uses 4 of the special fan screws that are supplied with the fans. The holes in the fan mount turrets are sized to allow the screws to drop inside and then can be screwed to the 8cm fan which should already be fitted to the control board cover.
Once fitted, screw in the two intake transits from beneath the printer deck and tighten by hand for a neat finish beneath.