Erzulis Boat 

Frame has the Italian chrome plate (under paint style) and I need to remove/replace a cable guide.

Have always fluxed heavily, heated and then removed. Do I need to abrasive blast the area to expose the solder, or will the flux and heat bypass the thin chromium and let me remove the crushed quide?

Thanks-

CliffordK

Do you know what the original brazing was done with?

It may be easy enough to grind/file the old guide off.

This should leave you with a tiny patch of exposed solder/brass/steel that you might be able to solder back onto.

unterhausen

it's very unhealthy to raise chrome to brazing temperatures. Look up hexavalent chromium. The best practice is to remove enough chrome that it doesn't get heated up.

CliffordK

@gugie has successfully silver soldered a chrome crown without damaging the chrome. Lots of flux.

Thus, grinding/filing off the old cable guide to avoid excess heating, especially if it was originally brazed with brass, then using a low temp silver solder to re-affix.

gugie 

I wouldn't braze onto chrome. I wouldn't trust the adhesion of the chrome to the underlying layer. It wouldn't look very good at any rate, and you'd repaint over it. I often remove top mount chain stay cable guides and braze a new one the bottom. I do this so I can route the derailleur cables under the BB. It's just cleaner looking to me that way. The upper ones get ground, filed and sanded clean, the bottoms get the chrome sanded off. Chrome dust ain't so great for you, so I wear a HEPA filter mask for that operation.

My procedure to protect the chrome from heat, and me from the chrome:
1. Lots of flux, enough to create a barrier.




after

2. Use a proper respirator.

3. Use good ventilation

I work in the semiconductor industry for my day job. Some of the gases we use are deadly. I deal with high current, high voltage systems. Understanding the dangers and how to minimize risks is the very first job at work. I didn't do the above job without doing my homework.

pwyg

Just file down the guides and sand away the chrome, either way you need to get to bare steel for silver to stick, bronze which I do not recommend can be done directly over chrome mainly due to the heat since it will cook off any chrome. If you do the latter you will want to avoid breathing in fumes the chrome fumes are bad. The first is the best option if you have a heat paste (anti heat) it will limit extra damage to the surrounding chrome and extra exposure to chrome fumes. I just recently re did a canti boss on a new frame where the owner tore it off. I limited the paint damage to within 1/2" around where I re-brazed the canti stud.