On Wed, 26 Feb 2020 12:51:49 -0800 (PST), jbeattie
wrote:

On Wednesday, February 26, 2020 at 9:18:30 AM UTC-8, Tom Kunich wrote:
On Wednesday, February 26, 2020 at 7:26:35 AM UTC-8, jbeattie wrote:
On Tuesday, February 25, 2020 at 3:39:12 PM UTC-8, Tom Kunich wrote:
On Monday, February 24, 2020 at 10:21:41 PM UTC-8, Jeff Liebermann wrote:
On Tue, 25 Feb 2020 10:41:06 +0700, John B.
wrote:

I an a bit afraid of the term "anti-seize", in this case, as so many
anti-seizes contain some sort of metallic particles to aid in high
temperature uses. Not very useful in preventing galvanic corrosion.
One of the most useful "stuff" I used on the boat was basically
lanolin with some sort of thickener.

The purpose of an anti-seize compound is to:
1. Electrically insulate dissimilar metallic components from each
other.
2. Squeeze itself into the tiny surface cracks and crevasses to act
as a reservoir in case the fastener looses anti-seize (or thread lock)
compound.
3. Reflow slightly when hot or under pressure.
4. In the absence of oxygen, polymerize with metals to form a
"sticky" bond. For anti-seize, this bond is rather weak. For thread
lock, rather strong.
"Basics on Anaerobic Adhesives and Threadlockers"
https://www.reliableplant.com/Read/24136/anaerobic-adhesives-threadlockers
You can use greases to insulate and block electrolysis, but will be
missing the benefits of #4. Some greases are also not so good with
#3, where heating and solvent attack will soon cause the anti-seize to
wash away and disappear.

Incidentally, the need for cracks and crevasses for lubricants and
sealants to function is why bearing and glued surfaces are not
polished to excessive smoothness.

The last ditch solution is to (carefully) drill the stuck fitting out
and re tap the hole but I hesitate to recommend that as it does
require a certain amount of skill, the proper tools, and so on.

Nope. Try that with a threaded insert (rivet nut), and the insert
will spin out of the CF frame before the screw is drilled out.
Everything will be fine, until the drill starts to break through the
bottom end of the insert. The drill will then jam, and the power of
the drill and inertia of the chuck and armature will rip the insert
from the CF frame. If the drill has a torque limiter, it might work,
but wouldn't want to take the chance. The nice thing about doing such
things by hand is one gets some feedback just before things go
horribly wrong. Experience is all about recognizing this feedback.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

It turns out that the screw was stainless and that it has a stainless "nut" cast into the frame. I removed the other end and looked at it. So there isn't any area for electrolytic dissimilar materials to interact in any way to seize the threads.

I guess the idiot who owned the frame before simply tightened a 2 mm screws way too much. I was wondering why I got the frame and all of the additional frame pieces for so cheap - 2018 for $500 and another $50 shipping. Two small paint knicks, one that is plain down by the off-side chain stay where I believe the off-side crank arm struck. I also have to discover why the new cranks hit the chain stay. One thing I know - a standard bearing for those BB-90's is supposed to be 37 x 24 x 7 mm. Trek (who is opening a local factory store!) uses a non-standard 37 x 24 x 7.3 mm bearing and chances are that is the problem.

The bike is a breeze to build. I hope this doesn't turn into one of your months long, agonizing wrong parts buying frenzies. BB 90 is a standard 7mm bearing width. They use a bearing shield, which you're probably missing. https://www.youtube.com/watch?v=mix25T4PdnY. If you still have play after installing the shields, then use a shim. If the crank arm is hitting, and there is no play in the system, then you have the wrong crank -- which would be impossible if you're using a Shimano Hollowtech road crank, but I fully expect that we'll go down some rabbit hole until you disclose that the crank is in backwards.

-- Jay Beattie.

The bearing was installed when I got it and the shield in on. Hambini made a point about the Trek using the none-standard bearing width so I am assuming that someone replaced the bearing with a standard BB90 bearing. Either that or the frame was made with one of the bearing cups too deep. Easily fixed by purchasing a Hambini BB90 Bearing. But these can only be installed after all of the wiring is installed since they are one piece and the Trek is three (actually four There are two shield cups that fit together.) pieces.

Which gives me the idea - Perhaps the cups were install reversed.

Groan. A standard BB90 bearing is 24X37X7 -- that's what your Trek uses. Rabbit hole here we come. The cups (bearing seats) are moulded into the frame. There is nothing to install backwards. The internal plastic shell is not structural and just a moisture guard, and the lip fits into a recess. Please tell me you are not using a GPX crank. In fact, WHAT CRANK ARE YOU USING?

Bearing replacement is a ten minute operation. I've done it . . . in ten minutes.

-- Jay Beattie.

Something I've always wondered about those pressed in BB bearings. In
normal practice pressed in bearings are usually intended to be a one
shot deal. Press them in and leave them for the life of the item, but
from what I read here replacing BB bearings is a common thing to do.
Is there any indication how many times one can replace a BB90 bearing
before the hole becomes sufficiently oversize that the bearing is no
longer held sufficiently tight to prevent movement?
See https://amesweb.info/press-fit/inter...alculator.aspx
for innumerable calculations regarding pressed in bearings and shafts.
--
cheers,

John B.