Update Aug 17th 2025: Uploaded STL versions of the models.
This is a powered respirator for woodworking or construction, or anything where a P3 / TH3P particulate type filter is appropriate. Powered by a Makita 18V battery, but modifications to other battery types should not be difficult. F3D project is included.
The respirator is built around a high-efficiency particulate filter from Optrel e3000x PAPR units -- instead of the Roomba iRobot filters common in other DIY respirators. I tried the vacuum filters but found the smell of the air nauseating. Also the Optrel filter has a much larger surface area and thickness and you can buy original pre-filters to protect the main pleated filter.
My main goals were:
- Easy to source replacement parts
- Proper respirator filters
- Good seals
- Comfortable to wear
- Single unit, not multiple boxes on the belt
- Battery under the main unit (to avoid twisting the belt).
Disclaimer: Use at your own risk, I am not a professional and there could be mistakes in my design.
Components:
- Belt mount:
- Harbinger 4" (10cm) weight lifting belt, widely available in fitness e-shops. I used the XL version, it is quite stiff which is a good thing because the whole assembly including battery is a bit on the heavier side.
- 40mm straps to mount the belt. There are cutouts on the backplate through which the straps should be threaded. Any polyester strap sold at the big box stores should work, but avoid too “slick” ones.
- 2 sliding buckles to secure the 40mm straps, a design is included in the .3mf which does not slip as much as the common backpack type buckles.
- 95x33mm blower fan NMB 09533GA-12Q-AA-00 (voltage controlled from 6V to 12V, no PWM)
- Using a different fan would probably need repositioning of mounting holes and probably also updates to the Versaflo tube connector that goes inbetween the blower fan and the breathing tube
- Do not use a weaker fan, because the particulate filter and prefilter are causing a significant pressure and airflow drop.
- Particulate filter TH3P for the Optrel e3000x, and corresponding pre-filters. Available at welding e-shops in Europe, and probably the US as well.
- 3M Versaflo helmet (I am using 3M M-206) and BT-30 breathing tube.
- Makita LXT 18V battery.
- DFRobot DFR0205 voltage buck converter with potentiometer.
- XH-M609 low voltage disconnect to protect the Makita battery from discharging.
- E-TEN 1021 single pole On/Off switch, stocked at many electronic components shops, or Aliexpress. I love this switch!
- D-profile 9mm weather stripping for window and doors. This is sold at all big box stores under the Tesa or other brands, compresses down to 3mm. This is to seal the filter.
- Tesa 05428 Universal Foam Sealing Tape 9mm. Available at big-box stores under different brands - a 9mm foam tape that compresses to below 1mm, with adhesive backing.
- Electrical textile insulation tape (sticky) between the fan and the housing to improve sealing. Or anything that compresses to about 0.5mm and seals.
- 20x heat-set inserts for M4 machine screws
- Machine screws:
- 8x M3 x 10mm (or 12mm) hex DIN 912 (mounting the PCBs, screw directly into plastic)
- 10x M4 x 45mm hex din 912 (mounting the filter housing and lid to the main body)
- 10x M4 x 12mm countersunk DIN 965 Phillips (or DIN 7991 hex) for mounting the backplate.
- 2x M4 x 40mm for mounting the fan, low profile heads, like the ones used for mounting drawer handles (ISO 7380, or BN 5952, not sure about the code).
- 6x M4 nuts (2 for fan mount, 4 for battery holder)
- Makita battery mount:
- Makita 643852-2 connection terminals
- 1x M4 x 20mm DIN 912
- 2x M4 x 35mm DIN 912 (40mm also works)
- 1x M4 x 20mm countersunk (DIN 965 Phillips or DIN 7991 hex)
Printing:
- I printed in PETG with 0.6mm nozzle, 2 perimeter walls on Prusa MK3S, layer height 0.3mm or 0.2mm.
- If printing with 0.4mm use 3 perimeter walls so that the heatset inserts have enough plastic around them. The M3 screws for mounting the PCBs also need some plastic to bite into.
- The 3MF file is saved from PrusaSlicer 2.9.0
BorisB
