Snapped screws in frame

MattDB

Senior Member
I bought a bottle cage for my hybrid and I don't know why but I used the plastic screws it came with rather than the metal ones already in my frame. I then knocked the cage and the screws snapped off - leaving me unable to use the frame for a bottle cage. I've taken to two cycle shops but their only suggestion was to have the frame re-threaded but both shops were adamant they were metal screws (they definitely weren't).

Any thoughts on how I could get these out? After getting a kitchen blow-torch for my birthday a thought popped into my head....... but then I imagined black melted paint patches on the frame and thought again.
 
If you cannot get a set of pliers on the broken screws to undo them, drill them out and put new nutserts in. Or try and cut a slot in the top of the broken screw with a saw and use a flat bladed screw driver to try and remove them.
Use a metal screw when you replace them ( I use steel ones as although aluminium may be a gram or two lighter, the heads tend to round off a lot easier)
 
didn't @screenman or @vernon post up a link to screwfix screw extractors recently on a similar thread? think one of them did... link is on another machine... looked like a useful set of tools for around a £5 for getting broken screws out in this situation... they are threaded the otherway to normal to work to unscrew the broken screw....

Edit: here we go..
http://www.screwfix.com/p/screw-extractor-5-piece-set/18643?kpid=18643
 

w00hoo_kent

One of the 64K
If they are plastic then you should be able to remove them without damaging the threaded inserts if you take a bit of care.

Presuming you haven't got a dremel, I'd go with melting a screwdriver in to them first (I'm presuming the frame isn't Carbon? I'd be wary of mucking about with heat around carbon) with a dremel I'd cut the slots as heating may deform the screw in to the insert threads I guess. I'd do the slots by getting a small drill bit and drilling a line. The remaining bolts shouldn't be in tight so once they move they should come out easily.

You can get left threaded drill bits, they are a bit more expensive, but will often remove a stuck screw as you drill in to it (presuming you have a drill and it can do left or right, they normally can to allow you to unstick drill bits). Screw extractors work in a similar principle. With plastic you shouldn't get the extractor jammed, which can snap them, getting out a stuck screw extractor inside a stuck screw is much much harder.

Again as it's plastic, you should be able to drill it out with a normal drill bit. Start small and work up. If it doesn't loosen them enough to wind out, eventually the screw will fall apart. You should be able to tidy the inserts with a tap. Biggest worry here would probably be winding the screw through the insert and dropping it in to the frame where it will be a faff to remove it. If you have a hand drill, I'd be tempted to go with that for more control, again if they were metal screws it wouldn't really be an option.

There is a definititve guide... http://www.diyfaq.org.uk/fasteners/fastener.html
 
Location
Loch side.
I bought a bottle cage for my hybrid and I don't know why but I used the plastic screws it came with rather than the metal ones already in my frame. I then knocked the cage and the screws snapped off - leaving me unable to use the frame for a bottle cage. I've taken to two cycle shops but their only suggestion was to have the frame re-threaded but both shops were adamant they were metal screws (they definitely weren't).

Any thoughts on how I could get these out? After getting a kitchen blow-torch for my birthday a thought popped into my head....... but then I imagined black melted paint patches on the frame and thought again.
If those screws were indeed plastic, Pale Rider has solved your problem. However, I suspect they are aluminium. Aluminium screws broken off in the frame's rivnuts (those crimped threaded inserts in the frame) spell trouble and is a job for a skilled mechanic. Aluminium, through galvanic corrosion, swells up and jams in its available space. This prevents it from turning. A plated steel bolt in there can actually be made to turn using a sharp instrument of sorts, but aluminium not.

Several bolt extractors exist, including the Ezee Out type that comprises a tapered carbon steel, reverse-thread device, a Grabbit and fluted rods. All of these require good access, which the frame's inner triangle does not provide. Imagine getting a drill machine in there and then drilling with precision into that small 4mm bolt. It is virtually impossible.

The solution is to remove the rivnut by cutting the flange that lies flat on the frame in three or four places, folding it up like a flower and dropping the rivnut into the frame. This then comes out the bottom bracket. After that, the rivnut has to be replaced.

I would hesitate taking the bike to anyone who hasn't done this before. The fact that they perhaps own a Ezzee Out is not a good indication that they know what they're doing. As Martin said above, breaking an Ezzee Out off inside the bolt is a disaster. They are extremely hard, but brittle and nothing in turn can drill those.

Let's hope it is indeed plastic in there.
 
Heat the tip of a small screwdriver - you get to use your blow torch for that.

Press screwdriver into the plastic bolt and hold.

There's a good chance you will have melted a suitable slot in the bolt and be able to wind it out.
This is how we remove broken off nylon wing fixing bolts on model 'planes! We use nylon bolts so that in the event of an 'arrival' the wings (or undercart) breaks off and reduces the collateral damage.

Just as PR says, it works a treat - but once you've pushed the blade into the end of the bolt, wait a minute for the blade to cool a bit, then try turning it. Otherwise, you simply melt away the slot you've just formed!
 

Cyclist33

Guest
Location
Warrington
Does the frame have a second pair of bottle cage fixings on the vertical choob?
 
OP
M

MattDB

Senior Member
Wow so much advice fantastic. Hadn't thought of heating up a screwdriver and melting a groove, that sounds like a starting point!
 
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