Pynchonite

Hello, all! I'm trying to refurbish an old Cannondale St-400 frame and one of the down tube bottle cage mounts has part of a bolt stuck in it. I've emptied an entire thing of Phil Wood Bio Lube into it and then tried to back it out with an awl and hammer, but nada. Any other ideas before I have to take a power tool to it? The bolt left a convex nubbin inside the boss, which is both stuck and difficult to get purchase on. Here's a completely unhelpful image of the frame in question and a cute dog. Thanks!

ridelikeaturtle

That should be easy enough to drill out.

02Giant 

+1, cautiously, with a left-hand drill bit.

wschruba

A good picture would provide more useful advice, but yes. Center-punch it (an automatic punch works best here) and use a small LH drill bit, working up progressively until you can either fit a small EZ out, or it backs itself out.

fietsbob

Have not put the BB in yet so maybe you can screw the stub in more
until it falls through and out the bottom ..

Rusted so much it broke taking it out? use grease next time.

C'dale uses Riv Nuts? You can drill those out and replace the whole thing..





...

Andrew R Stewart 

This one of the good reasons to have Rivnuts as bosses. You can remove the Rivnut's lip and punch into the frame the rest of the fitting (hopefully to have it rattle out the BB vent hole, if not then glue's your quite friend). Installing a replacement nis easy enough although I like to augment the pressing with epoxy.

BTW I have seen more then a few of these Rivnuts corrode to a bolt and become useless. besides the galvanic issues, often worsened by the electrolyte or acidic nature of sports drinks, too many shops and home wrenches don't bother to put a drop of oil on their cage bolts before installing. The soft nature of many Rivnuts (being AL) make the chance of cross threading too easy too.

This would be the time to check the remaining bosses for their tight fits into the tubes, repressing as needed. Andy

rumrunn6

following & hoping for pics

mrv 

+1 EZ Out https://en.wikipedia.org/wiki/Screw_extractor
- somebody remind me to give wikipedia $5 this year.....

Pynchonite

Thanks for all the replies!

Some important context that I forgot: there's no appreciable opening in either the head tube or bottom bracket shell to fish things out of if they fall into the frame, which is why I wanted to avoid using drills n' such. The frame came with both the down tube bosses messed up, each in its own unique way. Already fixed the other one, but this one's defied me so far. Drill it is. If you hear something like a jingle bell on the road and you turn around and you see a guy on a Cannondale swearing at his down tube, you know who it is. I'll follow up w/ better pics and progress.

Andrew R Stewart 

This is why I mentioned glue. Once the boss if freely floating about in the tube if you can't shake it out through a access hole in the shell (and most I've don could be although some required a lot of effort and needle nose pliers to pull what poke out a bit) then squeezing into the tube, via said hole, some glue is a quieting option. I've used sew up glue, contact cement and epoxy. Get a good amount in there and let the boss settle into the puddle. Andy.

Tamiya

wschruba

An important reminder: There's no reason not to start by trying to remove the screw. Left-hand drill bits are readily available (singly) from Grainger/McMaster Carr in the USA. If the stub doesn't come out with the drill bit, you can always proceed to a larger bit and take the whole rivnut out.

Just remember to centerpunch the stub, first.

WizardOfBoz

+1 on the centerpunch. And start by using a small drill to get a guide hole.

rumrunn6

I'm partial to straight fluted screw extractor bits with a proper tap wrench

fietsbob

Even says what pilot drill hole you need...

Pynchonite

That's an interesting idea - made me think of maybe using the heat gun on it. Also, wish I could say that that was my shop. I work at a shop in SLC, UT and someone had abandoned this frame before I started working there. Fixing it up in my spare time to use as a winter trainer. Trying to do one repair on it before each shift. And before someone mentions it, I work opposite the master mechanics, otherwise I'd just ask them for help

Le Mechanic

Tamiya

Pynchonite

Here're some pics. Brought it home. Literally haven't had the time to do anything else to it. After making a light mount for a dynamo light by drilling out a store-bought mount, I'm feeling much more suave with the drill, so we'll see how that goes. Just have to pick up some left-handed bits when I'm by Ace.

Broken bolt lurking within.


The whole shebang.

Pynchonite

Update: the broken bolt defeated my punch. Broke the tip off it before I could get anything like a recognizable divot made in the top of it. Tried drilling. Broke the bit, which, in hindsight, I should probably have seen coming (it was a 5/64", so not as stout as the punch). Next step? Different punch, maybe?

rhenning

Try drilling with a left had drill bit, the drill on reverse and there is a chance the bit will hook the remains of the bolt and unscrew it. Roger

wingless

rydabent

Combine several suggestions. Use the lightest oil you can find, even cut it with kerosene and let it soak. Tap in slightly, and warm the tube with a heat gun or hair dryer until warm to the touch, but not ruin the paint. Then if that fails center punch and use a left hand drill or an easy out. Above all be patient.

Pynchonite

Success! After a broken punch, a broken drill bit, and a few trips to the hardware store for ever-smaller tap wrenches, I got it out.




I used a version of this. Had to step up from a 5/64" bit to a 3/32" bit to get a good center hole and then finished with the 5/64" bit. Dumped a bunch of GT-85 into it before trying the extractor. Re-tapped the boss just to be sure that it was still functional (the bit had jumped around a bit when I broke it). Thanks for all the suggestions/tips/tricks and encouragement! All three bottle cage mounts accounted for!