Oil Mist Eliminator for Vacuum Pump

Print one of each file:

• 1x cap

  • I used 2 perimeters, 15% infill

• 1x body

  • I used 2 perimeters and 15% infill for most of the body, but switched to 4 perimeters and 80% infill for the top 20mm (otherwise, I had issues with the small end's male threads breaking off)

  • No support needed

• 1x body insert

  • I used 2 perimeters, 40% gyroid infill, no solid top or bottom layers. This piece is intended to let air through, but stop the steel wool in the body from poking down into the elbow

• 1x elbow

  • I used 2 perimeters and 15% infill for most of the body, but switched to 4 perimeters and 80% infill for the top 10mm (otherwise, I had issues with the male threads breaking off)

  • I printed in the orientation in the file (male threads at the top; only touching the build plate at the corner of the female threaded section) with supports set to 45 degree threshold.

    • I think this is the best orientation to be able to generate good supports that are also easily removable, but your mileage may vary

  • On my vacuum pump, this piece is required, as the body can't screw directly into the exhaust port because the handle is in the way. If your pump doesn't have this limitation, feel free to omit this part

  • If your pump has different threads on the exhaust port, feel free to replace this with your own adapter from the pump to the body's M24x1.5 threads. (With the loose clearance designed into the elbow part, the female end is more like M24.5x1.5, in case this information is useful.)

Printing details:

• I used ABS for temperature resistance because the oil reservoir gets hot

• All files are in the orientation I printed them

• All parts were printed at 0.2mm layer height

Other required parts:

• 2x O-ring, 28mm OD, 22mm ID, 3mm thick

• 1x P100 respirator filter, approx. 108mm OD (I used an old used-up 3M 2097)

• Fine steel wool (I used 0000, and it took 4 of the 12 pads of https://www.amazon.com/dp/B074MDTWQR)

  • You can omit the steel wool and just use the respirator filter; the steel wool only moderately helps with oil reduction but significantly helps with sound dampening

Assembly instructions:

1. Install O-rings - one goes in the groove around the male threads on the elbow, and the other goes in the groove around the male threads at the small end of the body.

2. Insert the body insert into the body so it's stopping up the small hole. (Air should be able to get through freely, but not steel wool.

3. Pack the body uniformly with steel wool. In order to make it more uniform, I unrolled each pad and fluffed it up before stuffing it in.

4. Put the respirator filter inside the cap, with the plastic bayonet connector coming up through the hole in the cap.

5. Screw the cap onto the end of the body. Make sure to tighten it down well. (If you want to double-check that the filter actually seated against the body's knife-edge-esque seal without any gaps, you can then unscrew the cap and make sure you see a uniform circular impression a few millimeters in from the edge of the filter, then reassemble the same way.)

6. Screw the elbow into the vacuum pump. Get it as tight as you can, then (if necessary) back off until it's at an angle where the body can screw onto it without hitting the handle. (The o-ring should make a good seal even if it's not cranked down super tight.)

7. Screw the body into the elbow.

Results

With the original oil cap that came with my vacuum pump, I noticed a visible oil fog coming out of the exhaust when the pump was running, and the PM2.5 particulate matter in the room spiked to 450 ug/m^3 (from a baseline of about 1 or 2 ug/m^3 when the pump isn't running).

With this filter, there's no visible oil fog, and the spike only goes up to about 20 ug/m^3, so it improves the air quality by a factor of around 22.