I sheared off a bolt fastening the dropout hanger to the chainstay on my Santa Cruz Blur Classic. It sheared off about 4 mm inside the end of the chainstay so I need to get it out without damaging the treads on the inside of the chainstay. My plan is to use a left handed drill bit inside a self-centering hinge bit to try to get the bolt out while protecting the threads in the chainstay at the same time. The bolt has blue Loctite on it so I’m hoping it will come out relatively easily. If not, once I’ve got a deep enough bore into the bolt I’ll try an extractor. If I can’t get it out I think I may need to retire my 15 year old friend. 
I’m looking for any suggestion that might help make this a successful operation. For example, should I use heat on the chainstay? It is aluminum and I’m concerned about heating it too much. What about cutting paste? Does it do anything other than extend the life of the drill bit? I don’t care if I ruin a $15 drill bit to save the bike. If I fail to get it out is there any place I could take it to get the dropout welded onto the chainstay? Is that a viable option?
Any suggestions are appreciated.
If she won’t move, and you love your frame enough, I’ve had a machine shop completely rebuild a cro-mo hanger one time on an old XC Diamondback frame. Cost about $200. They had to match the material exactly so it was a tad expensive.
Thanks @landandwater. The hanger is fine and easily replaceable. I’m impressed that Santa Cruz still sells them for 15 year old bikes. It is the chainstay which is at risk of becoming useless. SC used to sell rear triangles for these bikes too but no longer. Too old I expect. In this photo it the bolt on the end of the dropout going into the chainstay which sheared off inside the chainstay.
The revered drill bit extractor tool is probably your best bet. I’ve had mixed results with them. Still something a machine shop could fix. But it’s not cost effective for older gear. Dropouts are like bottom brackets. There are about 1000 standards, but many bikes use the same ones so they are not quite frame specific. Some exceptions though.
If you are confident in your own skills with tools I would suggest buying a few quality drill bits and a center punch. It can be very hard to stay centered when drilling a hardened bolt in a softer metal like aluminum.
Sounds like you are fond of this old beast. You might want to take the swing arm to a machine shop and get them to do it for you. Or find someone on the site who would do the job for beers 
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@darkmyth, from what I’ve read, the self-centering hinge bit should keep me on the bolt and away from the aluminum but I’ll keep a centre punch handy.
I love the bike but I’m also a stubborn old goat who should start squirreling away some money for something new which I’m sure I’d love just as much, if not more.
Thanks for the tip.
Is the bolt threaded into the chainstay or is it one of the fasteners? What size bolt is it? Hit it with some penetrating fluid a few times a few days before you plan on removing it. If your going to use heat I would use a soldering iron in the hole after you have a bit of a hole drilled into the bolt. Try to avoid heading the chainstay with a torch or heat gun, might damage the paint. I’ve had mixed results using “easy outs” but considering the material, torque and only blue locktite on the bolt it might be you best option first. If its really stubborn keep a can of that liquid air on hand, heat it up and shock the bolt with cold by turning the can upside down and spraying it. If all else fails you can drill it out and have it re tapped or have a heli coil installed. I’m a machinist by trade so if you have any trouble I could do any tapping or anything if it gets to that. Good luck
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I agree with the other folks in this thread. Nothing to lose by trying to drill it out. I had to do that on a seized expander bolt on my Yeti one time (in bloody carbon!). It worked, but I was scared to death.
Might be worth posting a wanted ad on Pinkbike for a Blur rear triangle, you never know what someone’s got hanging in their garage.
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@rhyno857, if I’d have to guess I’d say it is an M8 - 13mm long. I’ve been juicing it with PB Blaster for the last couple of days and plan to try to get it out tomorrow. Thanks for the tip with the soldering gun and the air. If I run into any trouble you might be hearing from me!
@brightwhite, good suggestion on the wanted ad if things go sideways. Somedays I wonder where everybodies old bikes go. We need a site like car-part.com but for bikes.
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The bolt came out a lot easier than I feared and I’m back on two wheels. I think the main reasons it was so easy was that the screw didn’t shear because the threads were seized. (I’m still not sure why the head sheared off). That and because the threads had been prepped with Locktite. So once I got a good hole drilled into the screw, the easy-out could get a good bite and it came out without any issues. I wasn’t able to find left handed drill bits in town. I think the screw would have probably come out with one of those. I centre punched before using the self-centering drill bit and those two steps made me confident that I wasn’t going to screw up the threads.
Thanks for all the tips. See you on the trails.
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