How to unscrew very tight screws?
August 30, 2012 8:29 PM   Subscribe

Looking for tips for unscrewing very tight screws that are down in a well.

I have this cute cat bank and I'm trying to open it up to see if I can remove the piece that makes the meowing sound, which got annoying pretty quickly. However I ran into an issue which was that the screws are screwed in very tightly and in attempting to unscrew them I realized I was beginning to strip the heads a little bit, so I quickly stopped. I would use pliers to try to turn the screws, but the wells are too deep for pliers to fit inside.

For reference, here's a photo showing one of the screws I'm trying to remove. It's the one in the center of the photo, not the battery cover screw to the right.

I'm not generally very "handy" and don't work on this kind of project often, so please give me your advice even if it seems obvious.
posted by capricorn to Grab Bag (13 answers total) 1 user marked this as a favorite
Round headed slotted screws are the worst. A couple thoughts: if you can find the fattest screwdriver that fits the slot, even if you have to apply a bit of pressure, that will give you moe grip. In similar cases, I have also folded a small bit of moistened, sturdy paper over the tip of the screwdriver so that it wedges into the slot in the screw. Slippage is your enemy, so steady downward pressure while turning is key.

Hopefully someone else will have a better idea, but there you go for what it's worth.
posted by The Deej at 8:37 PM on August 30, 2012

Generally, you want a screwdriver with an appropriately-sized head, and you want the end opposite the business to rotate. This allows you to apply even pressure while turning, since you don't have to work against the friction between the screwdriver and your hand.

Based on the size, you probably want a precision/jeweler's screwdriver.
posted by pullayup at 8:37 PM on August 30, 2012

Make sure your screwdriver is the right size. I've dabbed a little GOJO hand cleaner with pumice on the end of the screwdriver. The pumice gives the tip a little extra bite.
posted by Marky at 8:38 PM on August 30, 2012

You could also use a little Ajax on the tip of the screwdriver, but you'll need to wipe a damp cloth in the tip first.
posted by Marky at 8:41 PM on August 30, 2012

The things that pop into mind immediately are to make sure that the screwdriver is sized appropriately for the screw (maybe try some others if you have access to them), and to make sure that you're doing something to keep the bank from moving while you're doing the unscrewing.

This could be pressing down on the bank as much as you can without damaging it and/or doing something to brace it so none of the twisting motion you're doing with the screwdriver transfers to the bank causing it to turn as well; you want all of the twisting motion to go through to the screw.

Good luck!
posted by alphanerd at 8:42 PM on August 30, 2012

Also, don't be afraid to press down hard on the screwdriver as you're turning it.
posted by alphanerd at 8:43 PM on August 30, 2012

Touch a hot soldering iron to the screw for just a minute or two .
posted by hortense at 8:43 PM on August 30, 2012

Bit hard to tell, but that looks like a philips, posidriv, or similar (e.g. JIS, supadriv, quadrex, etc). They might seem somewhat interchangeable, but they're not really - particularly when your dealing with tight screws. Given you've already damaged the head, my bet would be you used a philips head screwdriver on a posidriv screw.

Rule 1: Use a proper screwdriver (i.e. not the shitty things included in home handy toolkits)
Rule 2: Use the right type of screwdriver (i.e. philips, posidriv, etc)
Rule 2: Use the right sized screwdriver (i.e. #00, 0, 1, 2, etc)

In this case, 1 and 3 are probably the most important. Get a screwdriver (with a decent tip, and a handle that's thick enough to grip) that's the right size to suit the screw; probably #00 or 0

Once that's taken care of, and assuming it's screwed into a plastic post, a short sharp twist in the wrong direction, or a light tap on the heel of the screwdriver with a small hammer, can help 'break' the grip of the plastic on the thread and make it much easier to unscrew.

pullayup: no, those things are shit - poorly made, the wrong size (ok, the largest may be a #00 or #0, which may be right), and for the larger sizes the rotating heel with narrow handgrip just makes it harder to turn the screwdriver.
posted by Pinback at 9:11 PM on August 30, 2012

Rubber band between the correct sized screw driver and the screw, downward force and some torque.
posted by iamabot at 9:29 PM on August 30, 2012

Since you have probably already damaged the head of the screw, I'm not sure that using the correct size driver (which would have been, and is in general, great advice) is going to solve things at this point. You may need to use a damaged screw extractor, and getting it down into the recess may be difficult. One like this might be long enough.

If that doesn't work, you may be in a very difficult position. If you have exhausted all other options, and have the time and inclination to do this, you can use a left-handed bit in a drill press as a last-resort screw extractor. (If you can find a left-handed carbide bit, that'd probably be great. But HSS will work.) You clamp the work gently, use a bit that's just smaller than the hole, running CCW (hence why it needs to be a left-handed bit, so that it's cutting into the screw head), with as much pressure as you can put on it. Either run the press at a very low / high torque speed, or use a pin wrench in the chuck key holes to turn it by hand. It's really the same idea as a stripped-screw extractor, but longer and thinner.

An old machinist taught me that trick and sometimes it will work when nothing else will.
posted by Kadin2048 at 10:43 PM on August 30, 2012

If you can find an impact driver with small enough bits, that should solve your problem. (I mean something like this or this, not one of the electric impact drill/drivers like this.) That gives you the combination of downward pressure (to avoid stripping the head) and turning force (to loosen the screw) that you need.
posted by Forktine at 10:57 PM on August 30, 2012

Self-link alert:
posted by primer_dimer at 1:20 AM on August 31, 2012

+1 get something which fits the head as well as possible. If you are serious about it, i'd suggest something like this as it has screwdriver bits, an extension bar and, importantly, a t-bar. (These little sets are hugely useful for all sorts of things)

Then get as much force onto the screw as accurately possible.

-clamp the bank as securely as possible somewhere. Since it's plastic you might want to use something soft to pad the clamp.
-attach a lever to your screwdriver; you can fit a spanner onto some screwdriver handles, otherwise you can use mole grips or use the t-bar from the socket set.
-put the bit into the screw head and tap-and-turn. Tap the end of the screwdriver with something metal and reasonably weighty as you apply gentle twist to the screwdriver. You can knock fairly hard, but dont twist too hard.
Once the screw moves, it'll come out.

Alternatively, fill the wells with a light oil; WD40/GT85 or similar, overnight so it seeps into the threads. That might be _just_ enough.
posted by BadMiker at 5:36 AM on August 31, 2012

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