cudak888 

A while ago, I picked this 1975 Raleigh Pro Mk.IV up, along with "Leo" the Bottecchia from an LBS. Local guy would chrome these things for the shop about five years ago, until said chromer retired.



It doesn't look like a bad job - except for the plated-over headbadge. But I have no idea whether this thing was baked to get the hydrogen embrittlement out of it.

The worst thing is that he had a chromed time trial funny bike that had been crashed too...and the BB had cracked all the way around on it.

Now I'm paranoid - enough that somedays I wish this beautiful thing would turn into an SBDU instead

Opinions? Am I building up a tubeset of inevitable failure? Throw it together and throw caution to the wind (easy to say when it's not your wallet)? Chuck it up on the alternate forum to get it to someone willing to make it wall art? Hem and haw over it for the next 10 years?



-Kurt

Pcampeau

Nice! I say do your best Cromovelato Mink Blue interpretation, then build. Look hard at the inside of that bottom bracket shell before riding.

cudak888 

I have to ask: What am I looking for?

-Kurt

Pcampeau

You mentioned the bottom bracket on a Time Trial bike breaking, I assumed you meant the shell possibly from being chromed? I could be misinterpreting. Just looking for cracks ahead of time.

cudak888 

Gotcha. Yes, exactly.

In all fairness, the time trial funny bike frame had been crashed though, and I noticed this only after repeatedly having trouble cold-setting it. I also wonder whether the BB may have been overheated by the builder to match up with the straight-up tube.

Before:



After:



Oops.





-Kurt

himespau 

Did the crash lead to the pinch in the seat tube too?

USAZorro

Was the seat tube already curved before it was "fixed"? That before picture looks like there's plenty wrong with it and I'm skeptical that the chroming had anything to do with the failure - though it likely hid the evidence for a while.

cudak888 

​​​​​
It was there when I started. I don't know if the crack was there or not. Discovered it when the seattube wouldn't stay on plane.

-Kurt

USAZorro

Just on general principle, it would seem that there would be fewer stresses on the bottom bracket of the MK IV than that atrocity of a TT frame. Unless you have some indication that the MK IV had been damaged and needed to have joints torqued or re-brazed, I wouldn't be concerned. The cursory inspection of the internals of the BB (as suggested upthread) should be sufficient to give you peace of mind.

repechage

Hydrogen enbrittlement... does not show until it shows.

Why I am wary of replating.

ascherer 

I get that failure due to embrittlement can't be predicted but is there any rule of thumb about how long it might take for that to show up, or is it more of a surprise guest without any development period? Asking for a friend...

cudak888 

Kinda my point with this thread - is there any way to know what one is dealing with, or is every 3rd-party chromed frame without history a gamble?

-Kurt

T-Mar

It's just like an overheated joint. It's impossible to predict when or if failure will occur. That failed joint could be due to overheating during brazing. lack of baking after plating or a combination of the two. If the plater typically performed plating of non-structural products using lower strength steels, it not have been baked post plating.

bikeaddiction1

It is going to be dependant on use. If you leave the bike sitting in a nice environment and never ride it you may never visually detect anything. If it is ridden hard structural deficiencies will show sooner. I don't know how you would know for sure without testing in a metallurgical lab, which would involve cutting test pieces which would render the frame useless anyway.

To me, if I had no history of hydrogen embrittlement relief of an aftermarket chrome plating job I would not risk riding the frame in any aggressive way. If you are just going to putz around on it and monitor for cracks/damage regularly, maybe, but what's the point in that?

cudak888 

What drives me nuts is that unlike most failure modes, there's virtually no rough documentation of frames that have failed due to (presumably) hydrogen embrittlement in the past.

-Kurt

Bad Lag

So, bake it out. If the hydrogen is still trapped in there, it can be baked out.

That Pro looks to be a VERY worthy frame. Do it.

T-Mar

I used to work for a company that manufactured military product for Hughes Aircraft and others. There was a time limit for baking to start, in order to be effective. I forget exactly what it was but it was quite soon as the parts were plated, maybe 2 or 3 hours maximum.

cudak888 

See T-Mar's post above in regards to baking.

As for the Pro's worthiness, it's the third I have. I'm a bit spoiled in that respect. I probably wouldn't have picked it up if it wasn't for the novelty of the chrome.

Also just realized how ridiculous the process would be to cromovelato the panels on this turd. I wonder if it could be done with an overlaminate transparent wrap and still look proper around the lugs.

Exactly. According to what I've read, 2 hours max.

Way past that now

-Kurt

non-fixie 

Hem and haw over it for another ten years. By then you'll be old enough to not care anymore and you'll just build and enjoy the bike.

cudak888 

Don't worry, it only took a year before I applied that logic to my other '75 Pro Mk. IV: https://www.bikeforums.net/classic-v...l#post21544824



Top tube paint be damned.

-Kurt

Mad Honk 

Kurt,
Most of those home guys only did a quick bath and electroplated, and didn't care about the environmental damage of the chemicals they used. Odds are it was a "quicky" job and not a good one. I doubt there is damage, but if it makes you feel better send it to me and I will dispose of it properly. Smiles, MH
BTW Did you ever get around to documenting my recently acquired Raleigh? Thanks

ascherer 

Well, shoot. Ive been riding the crap out of this 1970 Mark I. I haven't seen anything askance with it, now I'm gonna wonder.

Bad Lag

Do you guys have any understanding of why that is true? I am going to read up on this.

Sometimes the conditions, the context, of a caveat or maxim gets lost and all that is remembered is the conclusion. The maxim may be true when in a low cost manufacturing environment but may not be true in general.

For instance - if you need this process to cost less than $10 and take less than 1 hour, you have to do it within 2 hours of coming out of the plating bath. If you wait, you might have to bake longer to get the hydrogen to diffuse out and that may not be cost effective. If this is true, it can still be done.

In the world of C&V restorations, a long (slow) bake might not be a problem.

The key question is whether it is effective.

Bad Lag

One more point - if this was being done commercially and with some regularity by a plating shop for a bike shop, I would bet the baking would have been done. The default would be to bake it.

Why are you concerned it wasn't baked? Is it because you don't have a record of the bake out?

Bad Lag

From Wikipedia -
"If the metal has not yet started to crack, hydrogen embrittlement can be reversed by removing the hydrogen source and causing the hydrogen within the metal to diffuse out through heat treatment.[18] This de-embrittlement process, known as "baking", is used to overcome the weaknesses of methods such as electroplating which introduce hydrogen to the metal, but is not always entirely effective because a sufficient time and temperature must be reached.[19] Tests such as ASTM F1624 can be used to rapidly identify the minimum baking time (by testing using design of experiments, a relatively low number of samples can be used to pinpoint this value). Then the same test can be used as a quality control check to evaluate if baking was sufficient on a per-batch basis."

19. Federal Engineering and Design Support. "Embrittlement" (PDF). Fastenal. Fastenal Company Engineering Department. Retrieved 9 May 2015.

From reference 19 - "ASTM F1941 has a hydrogen embrittlement relief requirement for coated fasteners made from steel heat treated to a hardness of HRC 40 or above, case hardened fasteners, and fasteners with captive washers (SEM screws) made from hardened steel. The exact time and temperature of the bake is not specified, but times between 2 and 24 hours at temperatures between 350 and 450°F are listed as suitable depending on type, size of fastener, geometry and other variables. "

I'll look around some more. brb