Steel Charlie

Is there any non-distructive method to get a star nut out of a carbon steerer?

TIA
Charlie

cyccommute 

You could try to bend the wings of the star nut or try to cut them off. But a star nut in a carbon steerer has probably already done more damage than you can by trying to remove it.

Trakhak

You're trying to reuse the fork, it would seem, so what I'd do is (1) drive the star nut down further and (2) insert a compression plug or expander plug or whatever it's called.

Dave Mayer

Star nut in a carbon steerer? This is an absolute no-go. Would I ride a fork into which a star nut had been installed? Nope.

SoSmellyAir

Nah, could still get worse.

If (a) star nut is not inserted too deep and (b) OP does not need the full length of the carbon steerer, maybe cut the steerer just below the star nut?

icemilkcoffee 

Can you access the bottom of the steerer tube? If so screw a long bolt in from the top, and then at the bottom, slide a wrench socket up the bolt and use a nut to tighten the wrench socket against the bottom of the star nut. The socket will push the tabs inwards and then you can get it out.

Crankycrank

Drill out the center with as large a bit as you can fit and hopefully the "wings" will collapse or be bendable enough to break the nut apart. Just be careful that the drill bit doesn't catch the nut and start spinning it around in the steerer which could act like a saw blade.

Iride01 

Typically you just push it down further so the new star nut or expander plug has room. Or even out the bottom if the hole in the bottom isn't smaller or have a rim brake bolt through it. If this is a carbon steerer tube, you might be certain that it is in fact a star nut. Because you'll likely mess up trying to push an expander plug down. Also you should check to see if the maker of that fork is okay with star nuts being used in it. If not, then decide what risk it is to you if the steerer tube should one day become two pieces.

WizardOfBoz

As noted above your fork may already be dead and you just don't know it. That said, if you don't know how to say "This is messed up, I'm not taking any chance and am buying a new fork" you could try a hole saw. For a 23.45mm id carbon steerer, use a 22mm hole saw. The smaller the teeth the better. Possibly even use a carbide grit model. Replace the drill bit (they are replaceable) with a bronze rod turned down (on a lathe - I never said that this would be easy!) so that one end of the rod fits in the hole saw securely, and the other end is smaller than the star nut thread. Lubricate the bronze rod with grease. Then using minimal pressure drill away. If you are more of a manual hand-on person you could try to find a file. You'll likely need a very good one - the salient quality of a star nut is that it is springy. Springy steel things are usually higher carbon steels and are heat treated (that is, the star nut is likely a pretty hard steel). I could be wrong about that though.
In any case, gentle pressure, check frequently, and keep the bronze rod lubricated.
This is speculation - I've never done this. But if I absotively had to get a star nut out with minimal damage this is what I would try.
After you are done, if you want to ensure that the damage to the tube won't end up depositing you chin first onto the pavement, there are (for some sizes) glue in inserts made of solid metal bar stock. This one is from Zinn, for 23.45mm ID:

Andrew R Stewart 

WoB beat me to this suggestion, of a glued in pressure plug to address the scared and possibly damaged carbon steerer's ID. Andy

cyccommute 

Driving it down can make it more worser but, for the most part, the steer tube is already too damaged.

Possibly but it would be hard to tell if the steer tube is damaged by the outward pressure of the driving the star nut into the tube or how far down that damage might go.

base2 

Some forks with carbon steerers have a full length aluminum insert. Wound up and Cervelo come to mind. If that is the case, then carry on as normal as if it is any ol' aluminum steerer. Else wise Whoever installed the star-fangled insert did you dirty.

The good news is there is always a lighter fork out there in the world to upgrade to.

I would not trust a plain carbon steerer with knife edge loads in a safety sensitive application.

veganbikes

If there is a full length insert as base2 suggested then you can remove it normally but if it is a carbon steerer tube and there is an actual star fangled nut in there, I WOULD NOT use that fork. I just wouldn't trust it and trust whoever installed the SFN to have done it right because with carbon fiber there is no right way to do it because SFNs are designed for metal only. Sometimes you have to accept you just need a new fork and luckily there are TONS of great options from Whisky Parts Co. Enve, Columbus, Ritchey, Wound Up, Salsa Rodeo Labs, Cinq ...in tapered, straight, 1" with mounts for anything cages, fenders, quick release, thru-axles...basically there is probably a fork for most things aside from some really funky funky stuff.

I would get a new fork I can trust with all the warranties attached and make damn sure that I follow the instructions to the letter for install and what compression plug to use and make sure I take care of my stuff.

FBinNY 

The safe way to remove a star nut is to drill out the center then take the two leaves out one at a time.

As noted, a star nut MAY damage a carbon steerer, though not necessarily enough to matter, but why raise the odds by pushing it farther down or otherwise fooling with it.
Whatever damage is done is done, can't be fixed, cut could be made worse. Either leave things alone or remove it properly to not cause more damage.

Kontact 

I would think a reinforcing tube of carbon epoxied in to the damaged area would effectively "fix" it.

I make insert plugs out of stainless nuts, strips of cotton cloth and epoxy. It makes that last 1-1.5" of steerer effectively solid.


A step drill might be a good choice for drilling out the star. I imagine the star itself is something like spring steel.

FBinNY 

The problem with fixing it, besides probably not being necessary is that the repair will be in the same place as whatever expansion plug you plan to use. However if you go with one of those longer steel tube expanders, it will essentially act as a splint stabilizing any damaged area. For my part, I always try to position expanders so they straddle the place between the headset and stem or lowest spacer. This is the most stressed place in the steerer, so whatever support I can muster is welcome. (though not necessary unless the fork's maker says it is)
-----
Yes, star nuts typically have two spring steel leaves on an aluminum hub. The hub is easy to drill with a conventional drill. It's been a while but I believe I used a 5/16" or "N" drill. Either way you're not drilling the leaves, just the hub .

Iride01 

Have any of you actually drilled out a star nut? I'd think it'd start to spin when the torque from the drilling get's up to a certain point. And then there'll be gouges on the inside of the tube for certain.

I don't know. Just imagining that. I've never drilled one out myself. But I have had other stuff that I'm drilling out start to spin.

FBinNY 

Drilled out many. Never had the blades spin. Keep in mind that it's about torque and leverage. The blades are pressed hard into the wall at 3 diameters compared to the soft aluminum hub.

A reminder ---- do not try to drill the plate. A twist drill will seize and try to rip the plate out.

BTW. For those worried about accidentally catching the plates, you can use a spotting drill or countersink to remove the lip above the upper plate and expose the diameter before going farther.

WizardOfBoz

There's a first time for everything, Andrew. You made my night!

Steel Charlie

Thanks for the thoughts.
This is in ref to a potential purchase so just passing on it is certainly a possibility.
The first method that came to mind was a step drill to take out the center. Glad to see that drilling is a recommended approach. The glue-in sleeve looks to be worthwhile as well.

Thanks again for the suggestions
Charlie

ericoseveins

I've never had occasion to remove a star nut. If there are concerns about drilling I wonder if an oscillating tool with a thin carbide blade would be a good choice here.

wheelreason

Star nut in a carbon steerer, nice....

FBinNY 

I agree that it's less than ideal, especially with the wide assortment of expansion plugs out there. However, I believe the concerns to be overblown in most cases. OTOH expansion plugs aren't perfect either, and can also damage forks if poorly installed and over expanded.

If I should happen upon a fork with a star nut installed, I'd eyeball the the steerer for evidence of gouging as the plug was pressed, and absent of clear indications of an issue, would have no qualms about using that fork.

Duragrouch

This is not in my wheelhouse of experience, but based on the engineering mechanics of things, can you cock the star nut by holding under one side with a hook or one of those tools that looks like a small icepick with a 90 degree bend in it, then push down on the opposite side, until the nut is on edge to the bore axis, then hook the center hole and extract?

Regarding damage to a carbon steer tube, if damaged, I would think, it should be evident in fracturing of the resin?

FBinNY 

Definitely not. These starnuts are specifically designed to prevent camming. They use 2 spring plates separated on a hub, so they are essentially a cylinder.