How to make a clean hole in sheet metal?

Discussion in 'The Projects Forum' started by wayneh, Jun 16, 2016.

  1. wayneh

    Thread Starter Expert

    Sep 9, 2010
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    My new A/C came today and sadly there's no way to get the water out (to use it as a dehumidifier) without drilling a hole in the bottom of the case. This will void the warranty, but I ran it long enough to verify that it's working, so what the heck. (The unit is designed to sling the condensate on the condenser coils and blow all the water at your neighbors.)

    The case is painted metal, not too thick. I cannot access the inside of the case without a fair amount of disassembly. I want to do this from the outside only, if possible.

    I want to do a job that lasts and doesn't rust. So I'm thinking of drilling a hole (how?) for a hose barb and applying liberal caulk when I screw it in. That doesn't sound ideal but I can't find any better idea.

    Is there something you can insert and tighten, like a wall anchor?
     
  2. MaxHeadRoom

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    Jul 18, 2013
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    A step drill is one way in sheet metal with no access to the other side for a large or semi large hole.
    If there is going to be no pressure on the fitting and the metal is thin gauge, a hole the size of the bottom of the threads of the hose barb will self tap.
    Apply paste type pipe seal or RTV..
    Max.
    .
     
  3. AlbertHall

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    Jun 4, 2014
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    It may need the water on the condenser to help the cooling and may be very unhappy without that.
    I don't quite understand how, if it's supposed to get rid of the water, why it should collect in the bottom of the case.
    Can you be sure where it is safe to drill a hole without the drill damaging something inside?
     
  4. wayneh

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    I'll have to be careful, but yes, I can drill a hole without doing damage to anything else. There's a small, shallow well in the bottom of the case, maybe 2" x 4" and 1/8" deep. The slinger ring (100-year old technology!) is over that well and is the thing most at risk from me drilling. But I can drill off center and should have no trouble missing it.

    I figured I'd hear "step drill" suggested. I've eyed them before but never bought one. Time for a trip to the hardware store!
     
  5. MaxHeadRoom

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    One thing I would not be without now, even used it in plastic and wood as well as sheet metal.
    Max.
     
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  6. jpanhalt

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    Jan 18, 2008
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    I have a Frigidaire room A/C that is supposedly drain free. Guess what happens when it is really humid? Almost ruined the carpet. Go with the drain. I have done that already. A step drill as suggested is probably the best option. A punch, like Greenlee, will also do a great job, but is more expensive.

    For a one-time affair, I would get a HF step drill and run it slow with some cutting oil or even regular oil/kerosene/VMP Naptha/mineral spirits/etc.

    John
     
  7. wayneh

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    Yup, already planning which coupon to use at HF. Another free multimeter?
     
  8. jpanhalt

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    Good way to get some batteries cheaply. I usually get their vinyl gloves that I use a lot of.

    John
     
  9. Alec_t

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    In doing that isn't it acting as a dehumidifier? Why would you want to collect the water?
     
  10. #12

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    Aww, don't puss out. I used to take 8 of these apart and put them back together every day in my 40 hour job. It's just work.:p
     
  11. jpanhalt

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    Dehumidifiers do require drains -- at least the ones I have seen do.

    The theory for the A/C is that the hot air after compression of the working gas, which is exhausted, will be able to hold more water than the room air. Thus, the hot air blows across the water condensate from the cooling radiator. That works to an extent, but when it is really humid, the temperature differential, the amount of water formed, and the inefficiency of the evaporator design allows that reservoir to overflow (my device did not have a shut down for when that happened). Thus, I ended up with a soaked carpet.

    John
     
  12. #12

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    At this point, I feel a need to remind you that the air conditioner in a closed space will increase the F temperature of the room. If that reaches unacceptable levels, you might have to arrange a partial vent for the hot air from the condensor side to the outside of the building. In the end, increasing the dry bulb temperature decreases the humidity, but if people have to be in that space, it might become insufferable. Arizona in my Ohio basement.:D
     
  13. jpanhalt

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    I don't know to whom you directed that reminder. I certainly didn't need it, nor do I think most on this forum need that lesson in simple thermodynamics.

    John
     
  14. joeyd999

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    A rubber grommet to seal the exposed edges?

    [​IMG]
     
  15. wayneh

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    Good idea, but I need to attach tubing also. I might be able to find a tubing, grommet combination that works, in place of the hose barb approach.

    It's running right now with just a 1/4" hole, and propped over the floor drain. It is making water, somewhat slowly. But at 5,000 BTU, it's using less wattage than my old dehumidifier. So some slowness is expected.
     
  16. wayneh

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    Exactly right, I need dehumidification in the basement. Pulling the temp down wouldn't "dry" it as much as pulling the water out and leaving the temp where it is. The water isn't collected (except to measure it), it gets sent to the drain.
     
  17. wayneh

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    Oh I'm sure it's no more that a few minutes with a screwdriver. I'm just trying to minimize any sign of tampering in case I ever have to go to war over the warranty. The hole in the pan is bad enough, but that's unavoidable. I can avoid opening the case.
     
  18. joeyd999

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    Hole? What hole?
     
  19. #12

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    I was addressing the Thread Starter, the one who saw me do all the calculations to compare an air conditioner and a dehumidifier under the same conditions, then resumed reading advertising and asked the same question he started with.

    If I did all the calculations for you and you came back with the original question, I would think you didn't understand Thermodynamics.
     
  20. GopherT

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    Nov 23, 2012
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    Get a plastic hose barb. The threads are much broader to grab a hole of approximately correct size. Also, slit one side of the threads, it will help it tap AND it will let the water out before it crests the threads of the hose barb.
     
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