Not that I'm going to do it or anything, but...
March 12, 2014 1:01 AM   Subscribe

Is it feasible to take apart, modify, and put back together again a hair dryer so that it works in reverse, that is, become a small vacuum? I assume I would have to make the blower work backwards to become a sucker, and I would have to direct debris into a little sack and away from the blower and power source. If I were going to do it, what would I do? How much work would it be? How ugly would it be, assuming rudimentary skills and a home workshop? If it's impossible-- why?
posted by blnkfrnk to Sports, Hobbies, & Recreation (10 answers total)
The best way would be to leave the insides alone and to design attachments that fit the task. This is how the STIHL electric leaf blower works that I have: if you mount a hose on the air intake and a bag on the outlet, it becomes a vac.

The problem is that the motor and fan blades of your hair dryer aren't designed to deal with dust, and there isn't anything you can do, construction-wise, to catch the dust before it goes through the fan. So there, an entirely new construction would be needed. The blades of the fan of my leaf blower, for example, are made to work as a light-duty shredder for the leaves passing through, when used as a leaf-vac. I have yet to see how well that design actually holds up, and was planning not to over-use this feature, so even here, I'm not really sure this is such a great idea. With a motor not designed for that kind of work: rather no.

To open the thing and modify the motor to go in reverse would almost automatically violate all kinds of electrical safety rules and isn't really the route one should go (thinking hazards and insurances).
posted by Namlit at 1:20 AM on March 12, 2014 [1 favorite]

I would take the £15 of time and parts this would cost to do and buy a dustbuster, myself.
posted by goo at 1:49 AM on March 12, 2014 [11 favorites]

This sounds like a hard road to me. I'm all for converting things into other things, but this doesn't sound like something that would easily work out well. Small portable vacuum cleaners exist. I would get one of those.
posted by mewsic at 2:24 AM on March 12, 2014

If you do want to make a stuff-sucker and just buying a dustbuster wouldn't be fun enough, I'd suggest going to a hobby store that sells RC stuff or using fans meant for electronics/PC that run off, say 12 Volts DC. If you're using something like a 12 Volt DC power supply, like a wallwart, whatever you're doing will be a lot safer than mucking around with 120 Volts AC when you're not sure what you're doing.
posted by sebastienbailard at 3:09 AM on March 12, 2014

The simplest way would be to fabricate a nozzle on the 'intake' side of the hairdryer. Soda bottles and hot glue/ duct tape could do nicely.

If you can't to get fancier, well, the success/ease of this project is largely contingent on how hairdryer itself is built.

Best case scenario,

Disassemble the hairdryer. Flip the fan/impeller. re-assemble. Use wicked strong glue as needed.

But maybe you can't remove the impeller - then you have to reverse the way the motor is wired, unless there's an electronic circuit in there (say to prevent electricity from going to the fan motor if it's stopped so as to prevent a fire) that can't be easily worked with...

The possible difficulties are myriad. But you won't know until you open it up.
posted by From Bklyn at 3:23 AM on March 12, 2014

Ok, so my approaches experimentally to do this (and I'm not saying they would work, but it is what I would try are:

1) Don't, it's crazy.
2) Find the heating element and disconnect it. Very thoroughly and properly isolate the wires going to it. Or make sure it's always on cold setting somehow.
3) Again with the, I wouldn't do it.
4) Open the thing up, find the fan blades, take them off the motor shaft and put them back on backwards. See what that does.

5)If that does reverse the air flow make double sure the heating element isn't on, otherwise you're sucking hot air through your device, that leads to fires and melting.
If it didn't, just hack the case up a bit. There is already air flow, just not in the direction you want, so modify the rear of the device where air is sucked in to make a nozzle there.
6) Put a bit of fabric or something as a filter over the front as a filter and a tube on the end as a nozzle.

The most important steps are 1 and 3.
posted by Just this guy, y'know at 3:28 AM on March 12, 2014 [3 favorites]

I would worry about having debris collect on the heating elements and then causing a fire. If they were totally disconnected (and probably removed, to avoid blockages) then I don't think it would be unsafe -- though as said above, just buying a cheap handheld vacuum would be the smarter approach.
posted by Dip Flash at 5:38 AM on March 12, 2014

Flipping the fan blade will almost certainly not work. Most (?) cheap handheld hair dryers use an impeller, which is a centrifugal pump that wants to push air (or any other fluid) outwards. At best, you're going to end up with a asthmatic vacuum that resembles a really loud light spring breeze, as the curved impeller blades fights centrifugal force to pull air inwards. At worst and most likely, it's still going to be a hairdryer (ie blow in the original direction), but much worse. At extra-special worst, it was using the high air flow to keep itself cool, and it's going to melt/catch fire/kill your dog.

Handheld hair dryers that don't use an impeller use a typical fan unit. If you flip one of these, it doesn't change the direction it blows air. it's like a screw, you have left hand screws and right hand screws. if you cut the head off of a right-hand screw and weld it to the other end, it doesn't change the direction of the threads. It's still a right-hand screw. The only way you could do this is to either reverse the direction the motor turns somehow, flip the motor to be on the opposite side of the fan, so that it's turning it in the opposite direction, or flip the entire motor/fan unit around. Or source a fan that blows in the opposite direction and attach it to the motor.

Plus, everything everyone else said. these things aren't designed to be sucking crap through their innards.

Having said that, if you wanna do it i'd say break it open and start poking around. maybe it's a DC motor and you can just swap the positive and negative leads going to the motor. Be ready to throw it in the junk bin though.

Impeller style hair dryer
conventional style hair dryer
posted by duckstab at 5:53 AM on March 12, 2014

I'll vote that you could do this. It will be ugly, it will work, but not well, and by the time you bought the parts to do it, you could have purchased a small vacuum that would be the exact right tool for the job. with that info, what you will.
posted by Ruthless Bunny at 6:00 AM on March 12, 2014

Great answers, everyone!

I'm not actually going to try, but I like to think about weird hypothetical projects for fun (how would I go about it if I wanted to build an armchair from scratch, how would I build a diving bell I could take with me on my bike, how would I make custom high heels for my friend) and this was an idea that popped into my head and wouldn't go away. Since I don't really know anything about electronics or motors, it's like a song getting stuck in your head when you don't know the lyrics. Thanks for filling in some knowledge...I'll leave this up for a while in case someone else has some more insight.
posted by blnkfrnk at 11:17 AM on March 12, 2014

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