Removing Cross-Threaded Screws from Hardware?

TeaDaemon asks: "I currently have an expensive (dual CPU) motherboard mounted in a rack case. One of the mounting screws is cross-threaded, preventing me from removing the board. The case is designed to prevent access to the back of the risers, so that's not an option. Does anyone have experience with this sort of problem? Can anyone suggest a reliable way of removing said screw without damaging the board or any of it's components? The screw is next to the PCI slots, and has a couple of capacitors and ICs near by. Any help would be greatly appreciated."

Comments

'ask hardware store'....or try this...

[avi33]

First off, everyone should have one of these. The dazzling array of bits should help you brainstorm halfway out of any problem.

More likely you need a drill with a bit extractor kit.

Not really sure what specifics you're dealing with, but just go into a real hardware store (not a harware shopping mall like home depot) and ask the guy (or girl!) with the most nicks and scars on his hands. They could probably do it with a swiss army knife.

~a

Cross-threaded, or Stripped?

[Euphonious Coward]

There's usually nothing to prevent just unscrewing a cross-threaded screw. You just turn it and it comes out. The standoff would be damaged, then, and you'd want to replace it if you could. If you can't get at the screw on the other end, though, that's hard.

What the poster may mean is that the screw head itself is stripped out. Most of the suggestions above seem to relate to drilling out a stripped screw head.

I said "usually", above. Sometimes, if it's cross-threaded, then when you try to unscrew it, you end up turning the screw and the standoff, and unscrewing the standoff from the screw on the other end. If the other-end screw is (or gets) loose, all three turn freely, and you get nowhere. Even drilling might not help, because the bit just spins the whole assembly.

If this is what really happened, the only solution is to get a grip on either the standoff or the screwhead. If you manage the former, you can just unscrew it. If only the latter (e.g. with a vise-grip) then you can drill it out. You might want to super-glue the other end of standoff into place afterward, if you can't tighten that side's screw.

In general, you should post a more precise description of your problem if you hope to get helpful answers.

Re:Zen

[clintp]

The relevant passage

The first [negative aspects of traditional approaches to producing Quality] is stuckness, a mental stuckness that accompanies the physical stuckness of whatever it is you're working on. The same thing Chris was suffering from. A screw sticks, for example, on a side cover assembly. You check the manual to see if there might be any special cause for this screw to come off so hard, but all it says is ``Remove side cover plate'' in that wonderful terse technical style that never tells you what you want to know. There's no earlier procedure left undone that might cause the cover screws to stick.

If you're experienced you'd probably apply a penetrating liquid and an impact driver at this point. But suppose you're inexperienced and you attach a self-locking plier wrench to the shank of your screwdriver and really twist it hard, a procedure you've had success with in the past, but which this time succeeds only in tearing the slot of the screw.

Your mind was already thinking ahead to what you would do when the cover plate was off, and so it takes a little time to realize that this irritating minor annoyance of a torn screw slot isn't just irritating and minor. You're stuck. Stopped. Terminated. It's absolutely stopped you from fixing the motorcycle.

This isn't a rare scene in science or technology. This is the commonest scene of all. Just plain stuck. In traditional maintenance this is the worst of all moments, so bad that you have avoided even thinking about it before you come to it.

The book's no good to you now. Neither is scientific reason. You don't need any scientific experiments to find out what's wrong. It's obvious what's wrong. What you need is an hypothesis for how you're going to get that slotless screw out of there and scientific method doesn't provide any of these hypotheses. It operates only after they're around.

This is the zero moment of consciousness. Stuck. No answer. Honked. Kaput. It's a miserable experience emotionally. You're losing time. You're incompetent. You don't know what you're doing. You should be ashamed of yourself. You should take the machine to a real mechanic who knows how to figure these things out.

It's normal at this point for the fear-anger syndrome to take over and make you want to hammer on that side plate with a chisel, to pound it off with a sledge if necessary. You think about it, and the more you think about it the more you're inclined to take the whole machine to a high bridge and drop it off. It's just outrageous that a tiny little slot of a screw can defeat you so totally.

What you're up against is the great unknown, the void of all Western thought. You need some ideas, some hypotheses. Traditional scientific method, unfortunately, has never quite gotten around to say exactly where to pick up more of these hypotheses. Traditional scientific method has always been at the very best, 20-20 hindsight. It's good for seeing where you've been. It's good for testing the truth of what you think you know, but it can't tell you where you ought to go, unless where you ought to go is a continuation of where you were going in the past. Creativity, originality, inventiveness, intuition, imagination...``unstuckness,'' in other words...are completely outside its domain. [...]

My favorite portion of ensuing discussion about the limits of the scientific method and some traditional modes of thought is the statement that

[...] as your Quality awareness becomes stronger, you realize that this one, individual, particular screw is neither cheap nor small nor unimportant. Right now this screw is worth exactly the selling price of the whole motorcycle, because the motorcycle is actually valueless until you get the screw out.

.

Excellent book, every programmer should read it. At least to be able to laugh when their boss uses the word "Quality". :)

Re:Drill it out --- Mod up as FUNNY

[shepd]

Umm, you do realise that magnets generally don't damage computer electronics apart from magnetic storage and CRTs, right? I'm sure you could find an odd case of something else they destroy (Floppy read heads?) but AFAIK, none of that will be soldered onto the motherboard.