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January 1, 2013 8:01 AM   Subscribe

How do you get a stripped screw outta a rusted thing?

I am late to the game in figuring out how simple things work, so forgive the stupidity. I have, on my wheelchair, a screw um screwed into something called a castor bolt that acts as an axle for one of my front wheels.

I went to replace my front wheels yesterday and found this situation -- I'd swap out the castor bolt with a spare, but because I am an IDIOT I failed to make sure I have spare screws around. I have two screws: one refuses to come out of the castor bolt, the other I got out but will only -- um -- rescrew a few millimeters back into the castor bolt.

This will get sorted with new parts in a few days or so when I order spare parts (tomorrow); howevs, I would like to function better until then -- a little nervous about going out and about right now.

Thank you, and boy do I wish I had taken shop class instead of home ec in middle schools.
posted by angrycat to Grab Bag (13 answers total) 2 users marked this as a favorite
p.s I've soaked the screws/bolt in liquid wrench, corn oil (overnight), and dish soap (this morning, to degrease it to the point where I could work with it).
posted by angrycat at 8:04 AM on January 1, 2013

I've never heard of using vegetable oil for this kind of stuff. I think WD40 is the best and most easily available option. Also, make sure your screwdriver fits very well into the screw's head.

Alternatively: Can you grip the head with a pair of pliers?
posted by Too-Ticky at 8:12 AM on January 1, 2013

There is a tool for this called an extractor which is usually for broken screws but can also sometimes work for stripped ones. Basically you make a hole in the messed up screw and then use this reverse-threaded thing to get it out. Here is a set of photos that shows up this works. Here are some more suggestions from the DIY group at StackExchange that might use tools you already have access to, a few good examples include putting a rubber band in the stripped area to get more stickiness that might help and/or cutting a slice in the top of the scraw with a hacksaw if you have one and then using a flathead screwdriver on it.
posted by jessamyn at 8:24 AM on January 1, 2013 [2 favorites]

the other I got out but will only -- um -- rescrew a few millimeters back into the castor bolt.

Why won't it screw back in fully? Did you damage the head of the screw so the screwdriver can't get purchase on it? Might you have started the screw at a slight angle and cross-threaded it? Is there some visible damage or obstruction in the threads of either the screw or the castor bolt?

It might help clarify things if you could post a clear (focused) close-up pic or two.
posted by jon1270 at 8:27 AM on January 1, 2013

It sounds like you want to preserve the screws/bolts, but I'll provide this advice for the more destructive or obscure ways too.

So less destructive ways are to get more leverage, to try to recreate or sharpen the slot pattern in the head and get a better grip with the tools you likely already have.

In that regard, a less common tool, the vise-grip which is a pliers with a tension screw and a lever, may help you get a better grip AROUND the screw head and let you twist the screw/bolt out by hand. It's sometimes difficult to get purchase but if you fuss it long enough, you can usually get it (unless the head is recessed). If you use a vice grip, spend time fitting it just right. I usually fit it for a gentle vice then ungrip, use the tension screw to make the fit so it'll be very tight and then clamp it on. If I can't clamp it, ease off of the tension a little while not clamped and try it again. If there's enough screw to grip, have the handle stick out at 90 degrees from the direction of the screw shaft for maximum leverage.

Allow me also to say that sometimes when a screw only screws in a few threads in, it can be damage to the thread, but it can also just be that you've got the wrong screw - some screws/bolts have different thread densities (spaces between threads), thread sizes and other factors that look the same but aren't when you put screw/bolt to nut (or caster washer).

There are also tools for restoring the thread to a screw/bolt that has had the threads stripped or damaged, but they're pretty obscure for a home DIY person's tool chest.

Another method folks have already talked about is making a new slot in the head. You can also, if you have a dremel (a small headed, high-speed, low torque grinder) or a hacksaw, do what jessamyn says - cut a new slot in the head and use a flat head driver to pull the screw out.

More destructive but sometimes effective methods:
- Use a screw extractor like jessamyn linked to.
- Use a dremel or hack saw to cut the head OFF, then cut a slot (with a dremel, likely) in the recessed head and use a small screw driver.

The most destructive, but sometimes unfortunately necessary (and this works far better with screw/bolt attachments that go through a washer or nut or cabinet door - where you only need to attack it from one side and the other will fall out) is to use a drill bit that's a little smaller than the screw and drill down through the head to remove it completely. If you match the screw diameter just right you can essentially drill out all of the screw from the fastener and the rest will sort of drop out of the works as filings.

Good luck! It sounds like today (depending on whether stores are open in your area) you'll need to rely mostly on the tools you have. In that case I'd probably go for using a conventional large plier assuming I could get some grip.
posted by kalessin at 8:50 AM on January 1, 2013

I volunteer at a bike repair charity and our first line of attack on rusted bolts is a nice grade of penetrating oil, probably the Blaster on that page. We use WD-40 to clean grease off stuff but that's about it. It's a lousy lubricant.

Apply the oil and wait about 30 minutes for it to penetrate, then try the bolt. If that doesn't work, reapply and wait some more. If you are still stuck, you can try the Vise-Grips as kalessin says but only if you have sufficient exposed nut to grab and are willing to risk crushing the bolt head.

If that fails, then we would work up to grinders, bolt extractors, or drilling it out. These are last in line as they are destructive and may ruin whatever the bolt goes into.

As an aside, new mechanics often don't understand the difference between a bolt into an object and a bolt that goes through an object into a nut. If it's the latter, you must hold that nut while turning or it will just spin.

One bonus aside: if you are working on a phillips head screw, be sure to apply strong downward force and go slow. Phillips heads will happily pop out the driver and strip the head and damage the driver. They're awful.

Good luck!
posted by chairface at 9:04 AM on January 1, 2013 [2 favorites]

Wow, you all are awesome.

Here are some photos. The wheel is about five inches across.

There is no visible obstruction on the threads of the screw or the caster bolt, although it's hard to see in the castor bolt. Feeling inside of it with a allen wrench doesn't run up against anything either.

I will work at it with the pliers a while; part of the problem is that it's real small and the castor bolt is hard to keep in place with pliers, fingers, or anything, even when it is free of grease, because of its shape.

I think what I will do is set aside a few hours to work at it with the pliers some more and swear at it, and then order some parts mailed next-day mail tomorrow. A bike shop would get the job done with some techniques you all mentioned, but they wouldn't have the special screws needed to replace any screw messed up.

This is like the Ford Prefect warning about towels: Always have extra special screws.

Thanks for the advice thus far!
posted by angrycat at 10:10 AM on January 1, 2013

Whoops here is the photo I meant to post, shows how far the screw will go in at present:
posted by angrycat at 10:12 AM on January 1, 2013

Whoah, got it! Essentially used an allen wrench that was a bit larger and happened to fit the stripped screw enough to get it in -- therefore I don't need to swap it out until I get the spare parts. Thanks everybody!
posted by angrycat at 10:43 AM on January 1, 2013 [3 favorites]

Good on there! Sometimes taking a bread to ask/discuss/vent is an important step.

For future efforts, if you get to the drill out point, go to extreme effort to drill absolutely dead center. Which is very hard. But makes a huge difference.

WD40 is good but a can of PB Blaster and patience (days of soaking) is sometimes successful.
posted by sammyo at 2:13 PM on January 1, 2013

A little heat can help the WD-40 to soak in; put the bolt in the oven @ 150 or so ( gloves might help when it comes out ) the expansion will also help to break any 'rust' bond between the parts, and the cooling effect when removed will help to draw the oil in farther which also helps.

"Reverse twist" drill bits bite into stuck bolts in shafts and help to get them out too; if you have a reversible drill.
posted by buzzman at 5:13 PM on January 1, 2013

For a stripped screw, you can sometimes use a thin, soft, grippy type material (a thin, wide rubber band works very well) and use it to "grip" the stripped area of the screw slightly better with the screwdriver. Works best with phillips-head screws. Just place the rubber band between the screw head and the screwdriver, and push down hard while turning. The rubber fills out the stripped area of the screw head, and gives you more traction as you turn. I use this method all the time to good effect.
posted by gemmy at 5:16 PM on January 1, 2013

Hard to see in the pic, but the one that won't go in looks cross-threaded, if you roll it so that the axle is what is contacting the surface (something narrow so screw hangs over the edge), you may be able to see a wobble. If the threads haven't been completely ruined you may be able get started straight again.
posted by 445supermag at 6:28 PM on January 1, 2013

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