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Build the Open-Mask Model A PAPR Blower.
Initial release: 2020-04-27. Corrections and feeedback are welcome.
Here are the instructions to build the Open-Mask Model A PAPR blower. Look over the Materials List to make sure you have what you need. A note about the fasteners: to keep parts count and costs down, all but two of the fasteners are the same length. If you have the budget you may want to use more appropriate fasteners.
Note: All Open-Mask.org devices are rapid emergency Prototypes that are not FDA approved
- Print Parts.
The settings used for the prototype units was: .1mm line height, 20% infill. Supports as needed.
- Use drill templates to mark holes onto the back of the enclosure.
Use the printed drill templates to mark where the holes will go. There are 6 drill templates: Top Left, Top Right, Back Left, Back Right, and Front. Some of the templates snap into the existing holes of the enclosure. If these aren’t snapped firmly in place the holes will not be in the right places. Use an awl or punch to press firmly into the holes of the template to dimple the plastic of the enclosure.
- Drill holes & cut outs for outlet and filter.
Note: The four holes that hold the belt loop on are much easier to drill from the inside of the case.
Use your 4.5mm (11/64″) drill holes that you just marked. Trimming the indicated standoff from the inside of the case will make inserting the speed controller simpler.
- Cut gaskets.
Remove the gasket that comes on the filter and discard. Use the gasket cutting templates and a sharp utility knife to cut out the new gaskets.
[ Picture coming ] [ Picture coming ]
- Caulk & install fan spacer.
Caution: Sealing the back of the fan is vital to keeping unwanted contaminates from entering the airflow.
Remove the sticker from the fan and place a generous amount of silicone caulk where indicated below. Make sure not to get caulk inside the brass colored round hole or the fan may not work. Firmly press the spacer onto the fan.
Tip: Twisting the fan wires will keep them organized.
- Seal seams of fan.
Caution: Sealing the fan is vital to keeping unwanted contaminates from entering the airflow.
The fan is made of two pieces of plastic that are snapped together and is not airtight. Run a bead of caulk along this seam and use a tool or your finger to press the caulk into the seam.
- Attach air box to fan.
Caution: Sealing the air box and screws is vital to keeping unwanted contaminates from entering the airflow.
Insert the two air box mounts from the bottom of the fan as shown.
Seal the air box and fan by putting a bead of caulk around the bottom of the air box. Line up the holes inside the air box with the holes in the air box mounts and insert screws though the air box and into the air box mounts to mate the air box and fan. Make sure the screws are also airtight with caulk.
- Install and caulk outlet onto fan.
Caution: Sealing the outlet is vital to keeping unwanted contaminates from entering the airflow.
Depending on your 3D printer, the back of the outlet may need some sanding. Press your outlet onto the fan. This will be a very tight fit. Make sure the outlet is on correctly by performing a test fit. Place the assembly into the enclosure to make sure it all fits. If all goes well the fit will be tight but you shouldn’t have to force anything together. Once happy with the fitment run a bead of caulk where the outlet meets the fan.
Note: The back side of the outlet is slightly different than the front. Take care to affix the outlet so the back is away from the air box.
- Put controller on mount.
3mm nylon screws are preferred but the same type of screws used to mount the air box will work.
- Solder wires to power jack.
Solder a short piece of red wire to the positive (center) lugs and a short piece of black wire to the negative (barrel) lug. These wires should be just long enough to reach from the power jack to the controller. About 80mm (3 1/4″). Use heat shrink around each wire. Strip and tin about 3mm (1/8″) of the wires
Tip: Twisting the wires will keep them organized.
- Wire power plug and fan to controller.
The wiring instructions for your controller might be different so double check with the instructions that came with your controller.
Note: Putting caulk over these wires will help keep them in place during use.
Caution: Double check the instructions that came with your controller.
- Solder wires to the 2.1mm plugs.
Solder a short piece of red wire to the positive (center) lugs and a short piece of black wire to the negative (barrel) lug. These wires should be just long enough to reach from the power pack to the power plug on the PAPR blower unit. About 40mm (1 3/4″). Use heat shrink around both wires.
Now is an excellent time to test your wiring and components. Plug everything together and make sure it all works.
- Install fan / air box assembly.
Insert the fan and use two screws to keep the assembly in place. Make sure you use washers and lock nuts. Put a bead of caulk around the outlet to seal off the outlet from the enclosure.
- Install controller.
Unplug the battery but leave the power plug and fan unit wired to the controller. Use two screws to hold the controller in place. Make sure you use washers and lock nuts.
- Install belt loop.
Use four screws to attach the battery holder to the enclosure. Use washers and lock nuts to make sure it won’t come loose.
- Install battery holder.
Use the flat head screws along with washers and lock nuts to fasten the battery holder to the enclosure.
- Install power jack.
Insert the power jack and tighten the nut that came with it.
- Install enclosure front.
Follow the instructions that came with the enclosure to make sure it will seal properly.