Did my simple cleaning bite me in the butt?

Hey everyone,
I feel like a child admitting I did something I wasn’t supposed to do to a parent right now. Please don’t yell at me…

So, I do a lot of medium draftboard on my GF and noticed the other day that my exhaust fan was sounding, different. I do the regular maintenance on everything else in my machine but not the exhaust fan. It was bad. My machine is located in a basement and I do not have the means to bring it outside for the recommended fan cleaning. Here comes the part that makes me wince. I have all the tools to remove the fan so I carefully did so. I wiped everything down so that it was nice and new looking. I then reinstalled the fan and hit the magic button on my next piece. What happened next baffles me to no end.

As soon as it got to cutting the draftboard smoke started pouring out the front of my GF. I canceled that print right away and assumed that I installed the fan backward somehow. Upon further inspection my fan was put back the way it was before and the rotation is correct. During start up, with the lid open and very carefully, I put my hand near the fan when it spun up and felt a surprising amount of air that was blowing into the machine… I’m at a loss. I’ve been messing with this for 3 hours now with no new results. I have a plus so there is no heat sink in the way. I even let it go for a bit and went outside to see that a lot of smoke was still going outside but now also going into my shop. Removing the fan was a no no I’m sure but it’s too late for that. Does anyone have any thoughts as to why this is happening?

Sorry GF mom and dad.

Did the air filter tab accidently get toggled on?


Seems like the fan is installed backwards.


That is about the dirtiest material you can use, so it is not surprising that it was smoky, There are deliberately gaps everywhere with the expectation that the exhaust is sending stuff out such that air only flows in from the gaps. It is possible that working on the fan created a cascade of dust bunnies that then created more resistance in the hose when you started back up again so you might want to use that brush specifically designed for brushing dryer exhausts.

:thinking: Another thing to check is that the main lens is installed “cup side up” as that will produce more smoke and less cut, and is an easy thing to mess up.

External fan is still disabled.

I triple checked the direction of the fan to posts by other people before or even without removal.

I have a clear vent hose and can see there are no build-ups of bunnies. I get that a small amount can leak out with draftboard as I’ve cut more than 100 sheets into all sorts of fun bits in the last 5 months. My mirror is in correct as everything cuts perfect. The only difference is that I removed the fan and cleaned it…

That suggests the fan is backwards, explaining why there is smoke blowing out of the machine.
Removing the fan would not break anything, as long as the electrical connection wasn’t damaged.
Even with being sure I had put it back oriented correctly, When I work on something and that results in abhorrent behavior, the first question to myself is “What is the last thing I touched?”

where you are, my next move would be to reverse the fan to prove me right - or wrong.


Is it possible to reverse the polarity of the fan plug or is it keyed so you can’t?

Is the exhaust fan running? I mean is the sound normal? If you have it in backwards or it’s not running at all it’ll sound really different.


It is keyed. It’s is running and sounding correct that is why I’m baffled.

I can watch the rotation of the fan during startup and see that if I turn it around it will blow into the machine in full force. Also, I can go outside and see a fair amount of smoke being blown out. If the rotation was backward I don’t see how it could blow the damper door open. For some reason it is doing its job of blowing outside but now there seems to be air also going out the sides of the fan if that makes any sense? Almost like the fan blades are not at the original angle (which they appear to be).

I did want to check what you suggested and just thought of a simpler way than those agrivating screws that hold the fan in. I removed my hose on the back of the machine and felt a significant amount of air blow out the back on start up. It is now verified to be going the correct direction. I appreciate all suggestions in trying to fix this though. Keep em coming!


Is the connector for the fan plugged in securely? (Right slot and all that?)

thanks for sharing your experience. This is precisely why I haven’t attempted to clean my fans. I know I will screw something up. Cleaning is necessary at atimes, but it does seem to invite the gremlins in who think they can help.



Thanks to @PrintToLaser for getting me there! I only did a 30 second cut to test this before bed and will double check things and update again tomorrow. When I pulled my house off the back to check air flow I noticed that it came off a little too easily. To answer @PrintToLaser “what did I touch last” it appears to have been my clamp on the back. I don’t believe it was securely connected because when I reinstalled it there was a reduction of about 95%off the smoke or the front of my laser.

Is it possible that air not escaping out the exhaust hose completely would somehow cause it to build up in the laser? More to come tomorrow!



I counted my chickens before they hatched everyone…

I am half way through a 20 minute cut on a sheet of draftboard and my shop is filled with smoke. I have a message into support. I had to have either damaged the fan somehow or it was on it’s way out when I decided to clean it. There was no smoke leaking out before I cleaned it. I may be investing in an external inline fan sooner than I had planned!

Is there any blockage in the hose or the flap door on the exterior end of the hose?

Everything seems clear. 80%off the smoke makes it outside.

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Or that there is possibly a blockage at the end of the connect, since you see nothing in the hose. Since you can remove it so easily, why not get an external fan? Quieter, and would LIKELY fix your issue.

Yeah, I ordered it today. It’ll be here by Wednesday and probably before I hear back from support. Oh well.

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Make sure your air intake vent on the front right didn’t get blocked by something while you were moving things around.


This may not help fix this problem but i stopped using that fan a long time ago. Get yourself an external fan like what people use in grow tents. Put your settings on air filter attached mode. Itll bypass the fan and really suck out all the smoke. Its a night and day difference sound wise.