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We have an outdoor lamppost that is controlled by a switch from inside. Originally the light was burnt out, so we replaced it, and it started working again, but it blew out the light again. So I'm trying to look at the socket to tighten up and/or replace it, but it's impossible to get at unless I undo a couple of screws at the interface between the post and the 'fixture'. They're all rusted and painted over, and I'm having limited success. Things I've tried with varying amounts of goodness:

  • Naval Jelly rust dissolver
  • A screw extractor bit
  • metal drill bits to drill out the screw

None of them has really done the trick, but I'll keep trying. The fixture is probably stuck on the post as well - but it does appear to actually have a collar, so once I get these screws out I may have better luck with a mallet to dislodge it. Any other suggestions?

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Since you've tried several ways of removing the screws I can't imagine what they look like now. Would it be possible for you to post a photo of the fixture somewhere (say, flickr or twitpic) and then give us the URL here? –  Bill Bell Jan 1 '12 at 22:21
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5 Answers

Having dealt with a bunch of door hinges that have been painted on, I've formulated a series of steps that have worked so far:

  1. Remove the paint/rust from the screw head.

    For paint, I've found a gel paint stripper to be effective. As you point out, naval jelly or a penetrating oil can be used on rust. You can also try using a rotary tool fitted with an abrasive brush to quickly clean the screw head.

  2. Use a manual screwdriver to get the screw started.

    Too often, I've gone straight to the power screwdriver and stripped the slots in the screw head. This is particularly common with Phillips head screws. Using a hand screwdriver reduces the risk.

  3. Re-slot the screw head.

    Using a cutting disk attachment on a rotary tool, it's possible to either add a slot or deepen an existing slot on the screw head. Aim to create a single groove deep enough for a flat head screwdriver to engage.

  4. Apply heat.

    A heat gun (which could also be used to remove paint in step #1) will temporarily cause the metal in the screw to expand slightly. As the screw cools, it should also loosen up and be easier to remove.

  5. Drill or chisel out the surrounding area.

    If all else fails, you ought to be able to extract a screw by drilling out or attacking the area around the screw with a chisel. (Presumably you could use a rotary tool for this step as well, but since I obtained one I haven't need to go past step #3.) If you dig out enough material, you might be able to grasp the screw head with a pair of pliers.

It probably goes with out saying (but I will anyway) that you should wear proper safety equipment such as gloves and goggles when handling harsh chemicals and using high-speed rotary tools.

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I've screwed this up so many times (pun intended). I'm hoping to create a canonical answer for posterity, so please let me know if you'd do things differently. –  Jon Ericson Jul 20 '12 at 0:46
    
+1 on top of my vote for a nice answer! –  Steven Jul 20 '12 at 2:01
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up vote 3 down vote accepted

In the end I ended up using drill bits to drill out the area around the screw heads and then I was able to get enough leverage to yank the top off. We were going to replace the lamp head anyways, so this ended up working out fine.

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It's kind of expensive just for this purpose, but I find an impact driver works wonders on rusted screws, screws with messed up heads, stubborn screws and bolts, etc. I've been shocked at how much I use my cordless impact driver -- I use it so much that my cordless drill is now only used for drilling.

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Two thing to try for a badly rusted screw. The first is heat - get a torch and heat it up. That should also burn away any paint as well. Of course, it will also affect the area around the screw.

And when a screw is completely mangled, you can always re-slot it with a dremel - take a look at this.

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A dremmel tool with grinding or cutting attachments may be a good way to go after this guy. Sometimes you cut of the head, sometimes you cut a new screwdriver slot. Diamond tools at harbor freight are cheap and may work. An angle grinder can be used on big guys. I have normally only had to use this on really rusted material or hardened hardware. Grinding might give you a good piolot for drilling out the sucker.

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