HOWTO Clean the Laser Exhaust

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The exhaust vent screen when nearly fully clogged (above) and partially scraped clean (below)
The exhaust vent screen when nearly fully clogged (above) and partially scraped clean (below)

The exhaust system for the big laser cutters, Bumblebee and Wolverine, becomes clogged periodically when fine particulate accumulates in the blower and on the pest screen. Here are instructions on cleaning the system. It's best done by two or more people.

Be safe: Wear at least safety glasses and a dust mask. You'll need to be up at the ceiling in the genie, handling a heavy (~30 lb.) fan and exposed to concentrated amounts of ash, plastic particulate, and whatever else comes out the back end of a laser cutter. Don't wear your nice clothes.


Tools you'll need:

  • Safety glasses
  • Dust mask/respirator
  • (Optional) Face shield
  • 9/16" socket wrench
  • 9/16" combination wrench
  • Hammer or mallet
  • Flashlight
  • 2 wire brushes, one of them duct taped to a ~12" long, skinny piece of scrap wood as a handle extension.
  • Shop vac with long hose extension (to reach up to the duct)

The Genie needs a clear path to the very back corner of the shop, west of the Wood Shop dust collector. Usually this means sliding the plastic shelving rack that's closest to the corner out of the way. Be careful not to drive into the sump pump or the steel brackets bolted to the floor for the dust collector. Try to get as close to the back wall as possible without driving into the sump. (Optional): It's helpful if you can back the genie into place. With the blue tray positioned under the fan (and also emptied), it's less work to lower it down.

Fan removal

From the outside, the fan looks like a flanged steel tube with some wires coming out the side. Start by unpluging both the power cord and the re-purposed network cable. The fan is bolted through the flanges to ducting on both sides, with around 5 or so 3/8" nuts and bolts per side. It's also attached to the roof with a chain, which can support it once it's unbolted. Unscrew and remove the nuts, leaving the bolts in place. Then start removing bolts. Some will be pretty easy to pull out, others will be stuck. The stuck ones can be removed through a combination of pushing up on the fan, to take the weight off the bolts, and tapping them out with a hammer or mallet. When you take out the last bolt, the fan will shift down a few inches, but it'll still be suspended from the chain. If you backed the genie in, raise the genie so the fan is supported by the blue tray, disconnect the chains, and then carefully move the fan to the floor of the genie. Otherwise, it takes a little more strength and balance to unchain the fan and not drop it. At this point, things may also start getting dusty, since the vent is now open. You remembered your dust mask and glasses, right?

Fan Cleaning

Transfer the fan to a cart, and take it somewhere well ventilated, preferably the loading bay or outside. The fan blade and the inside of the housing will likely by caked with dust and crud. You can scrub most of that off with a wire brush. It's also helpful to take the fan outside and blow it out with compressed air once it's been. Just try not to blow the crud onto anyone's car.

Deeper cleaning of the fan by disassembly has not yet been attempted, but may be necessary in the future.

Vent Screen Cleaning

Here's where the dust mask and face protection is necessary. With the fan out of the way, you can now see into the ducts, and a flashlight will help with that. The screen is at the far side of the duct that goes through the wall to outside. This is where you'll need a wire brush with an extended handle. The crud comes off pretty easily when scraped at. As you clean it off, it lets more air flow through, especially if it's cold out and warm inside, and this breeze can blow the dust around, into your face, etc. Once it's pretty clean, use the shop vac to vacuum out the dust, so it doesn't just end up in the screen again.

Replacing the Fan

Make sure the fan is pointing the right direction. Beyond that, mostly see Fan Removal in reverse, but in short: Raise the fan and connect the chains. Support it so the holes line up. There are many extra holes, but the ones that do line up correctly are marked. Put in the bolts (push up on the fan as needed, if the bolts get stuck), tighten the nuts, and finally plug both cords back in. Drive the genie home, plug it in, put away tools, and update the log below. Thanks!

Cleaning Log

Date Cleaned Cleaners Notes
9/15/2015 Mike Not sure when it was last cleaned before this
6/16/2016 Mike
10/27/2016 Mike, Augie, Nathan S
12/15/2016 Mike, Augie, other?