Lincoln 3350 "Pseudo-PARP" Conversion

• Lincoln 3350 welding mask - the regular one is just fine.

• 12 Volt Blower - this is the blower I used for my 

• 12V USB-C Module - this is what you use to power the fan and circuitry

• Motor controller with pot - This is pretty easy to wire up; power in from the USB PD module.

• M3 screws

• M3 heat set inserts

• Lincoln KP3940-1 PAPR Headcovering

• Some adhesive back velcro strips to afix the PAPR headcovering into the mas.

I'd recommend following the RespiraWorks instructions for wiring and hooking up the USB PD module; I didn't put in the diode and cap and the thing can stall out on starting because of motor back EMF unless I start the motor on the lowest speed.  In any case, it's pretty simple to wire up; make sure to note the phase wiring so the motor spins in the right direction.

My model for the filter body has 4 parts:

• Lincoln 3350 Mask Vent - print as shown with supports; there are ribs inside the vent and it should bridge just fine. 

• PARP Main Body - print in the orientation shown with the outlet supported on the build plate.  Use M3 brass inserts for the screw holes on the bottom (these are used to connect the filter splitter) and on the top (these are to secure the back plate and belt clip).

• Filter Splitter - print on the side with supports under the 3m filter connectors.  The ribs inside the body are to be broken off after printing; they provide more than enough support and should ensure bridging works as expected.

• Back - Goes on the back of the housing.

• Belt Clip - goes on top of the back plate. Use M3 screws through belt clip and back to secure to the main housing.

The blower and other parts install as shown in the photo.  I used a bit of duct tape to seal around the outlet of the blower.  It is not super important as you're just going to leak clean air.

When you put the filter splitter on, use some silicone caulk to seal this to the main housing -- you don't want dirty air bypassing the filters.

To make a good seal for the 3M filters, I cut some little rings of thin squishy foam material and used them to make a nice tight seal between the 3m filter and the housing.  

The vent is positioned inside the welding mask.  I drilled some holes and used M3 screws to attach the vent to the mask.

The PAPR head gear is pretty self explanatory.  I used some adhesive backed velcro strips to mount it into the mask as shown.  I just formed the seal around the vent and used velcro to seal it.  I said it was pseudo-papr right?  The actual genuine article from Lincoln integrates the vent into the head gear; I didn't have the desire to try to remodel all that.  This works good enough-ish.