How to drill out chainring bolts?

[hypnos]

I have several hopelessly stuck chainring bolts, so I have decided to drill them out. Have tried several types of bits, including cobalt steel, without success. Does anyone have advice?

[otis]

If these are traditional chromed steel bolts/nuts I would try drilling them from the backside. The bolts will usually have a hole down the center so start with a drill just a hair bigger than the hole.

I would think any good quality HSS drill would work doing it that way, The plating should not be thick on the inside of the bolt. And they should not be hardened.

If you have some other type of bolt I guess it would be good to post a photo or description.

[ultraman6970]

u can use press drill, then you do like circles to get the bolt thinnner and thinner, at some point will crack off.

[rrudoff]

Left hand drill will sometimes break/spin it out if you can run your press in reverse. Also with drill bits you get what you pay for. Buy US made from a tooling supplier not hardware store. If you have a drill press can use carbide if you secure everything.


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[Veloo]

I had one "stuck" a few weeks ago. It was just spinning and the Park chainring nut tool wasn't any help. One of the nut notches was deformed/ angled.
For whatever reason, I decided to give my heat gun a try. Aimed at the problem bolt for a bit then took an allen wrench to it and it came off. Guess the nut expanded under the heat and grabbed onto the chainring, allowing me to turn the bolt loose.

[11.4]

If they're two-piece chainring bolts (front and back pieces) and are aluminum, use a countersink in a drill and work from the back. It just has to pop the rear flange loose and everything will fall out together. You can hold the bolt in place with an allen key or torx from the front.

If they're two-piece steel ones, use a conical grinding stone and do the same. The countersink or drill bit will catch and snap on the existing hole in the chainring bolt.

If they are one-piece bolts (typically alloy, and in most cases threading from the front, through the chainring, and into the spider in back), don't try to drill them out. You want to try to break the bond between the bolt and the spider. Hopefully you took the bolts out when you bought the crankset and used anti seize on them. If you didn't a heat gun is probably your best bet. On recalcitrant single alloy bolts I'll even use a propane micro torch. (Since newer one-piece bolts tend to be torx be sure you're using the right tool -- a casual look can make you use an allen key which won't hold well enough and will strip out the bolt.) I have a torx t-wrench that I can clamp into a vise with the torx tip pointing up. Then lower the crankset onto it, wrap the crankset in a heavy towel, and just lean into it. Sooner or later it'll pop free and typically come out intact.

[nicrump]

PB blaster and better fitting wrenches.

[hypnos]

Finally got them out. Thank you all for the advice.

[Peter P.]

Originally Posted by hypnos

Finally got them out. Thank you all for the advice.

You gonna tell us how or leave us in suspense?!