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Color case hardening a frame: A Strip and torch job

Posted: Wed Jan 09, 2013 3:00 pm
by LouisN
Sorry if it's a stupid question.

Anybody thought about stripping a steel frame, and give it a color case hardening treatment, like shotguns's steel parts ? If there's something that's enduring the test of time over tough outside conditions with steel, it's that one...?

Image


I thought it might look really nice ? I'm planning on building a commuter/beater out of an old Peugeot (and maybe using that finish)...


I even think I saw something that looked similar on the gallery section, where the braze-ons were left "natural" on a road steel frame.

NOTE: I would only like to obtain the finish, and not go in the whole process about hardening the steel. Maybe I can obtain it by heating the tubes with a blowtorch, and either give it a "gun blue" finish, or even a matte clear.

Louis :)

Color case hardening a frame: A Strip and torch job

Posted: Wed Jan 09, 2013 3:00 pm
by Weenie

Re: Color case hardening on a Chrome-moly frame ???

Posted: Wed Jan 09, 2013 4:38 pm
by HillRPete
I don't think the blowtorch treatment will help with corrosion resistance. Would make for a unique look though. Cro-Moly (depending on the alloy recipe) is fairly corrosion resistant already, but why not clear coat, for extra protection, and carefree use, in bad weather, road salt leftovers in spring, etc?

Re: Color case hardening on a Chrome-moly frame ???

Posted: Wed Jan 09, 2013 6:11 pm
by GT56
why don't we collect all firearms, melt them and make bicycle frames out of them

Re: Color case hardening on a Chrome-moly frame ???

Posted: Wed Jan 09, 2013 11:22 pm
by LouisN
Found the WW thread:

viewtopic.php?

I'll try a call at Vanilla/Speedvagen....wish me luck...

Louis :)

Re: Color case hardening on a Chrome-moly frame ???

Posted: Thu Jan 10, 2013 6:12 pm
by LouisN
While waiting for answer...

....I weighed the frame : 2484 g................... :lol: :lol: :lol:

Though it would be cool to investigate if such a finish is do-able, I think I'll go a more simple route...


:lol: :lol: :lol: ....I'm afraid to weigh the fork now.... :lol: :lol: :lol:


Louis :)

Re: Color case hardening on a Chrome-moly frame ???

Posted: Fri Jan 11, 2013 5:49 am
by Geoff
Unfortunately, colour case-hardening would not be an appropriate finish for a bike frame. Interestingly, there was a Speedvagen frame a few years back that has an interesting look similar to that...

Re: Color case hardening on a Chrome-moly frame ???

Posted: Fri Jan 11, 2013 3:01 pm
by LouisN
I also asked people at Marinoni Cycles, a well known bike shop here in Canada.

I got a quick reply from Simonne who's been there for ever ( wife of Giuseppe Marinoni, and owner), giving the best customer service. I'll try to give an appropriate translation since the original message is in french:

" Does your Peugoet have brazed-on welds, or TIG weelds like the Speedvagen ?
We did that finish on our Strada model 5 or 6 years ago. With a blow torch on the brazed-on welds, and with the TIG on our TIG welds. But I can't tell you if you can do it without danger, because I don't know what kind of welds they were using. You still have to finish the frame with transparent primer, and clearcoat. It's more complicated than paint, and, to us, less resistant. I saw the color case hardening method on firearms at HOW IT'S MADE, and they don't have to paint them because they put them over heat treatment. You couldn't leave your frame without protection, it would rust immediately.
Regards,
Simonne.
P.S. Our winters are way too long for cyclists."


I think it looked like this:
http://www.woodcockcycle.com/photo_gall ... &photo=128"
http://velospace.org/node/15232"

Speaking of Marinoni:

http://cycling-passion.com/tag/giuseppe-marinoni/"

Louis :)

Re: Color case hardening a frame: A Strip and torch job

Posted: Sat Jan 19, 2013 3:03 am
by LouisN
I finally stripped the frame.

I liked the looks that I obtained actually. There's some primer residue that I can't completely take off, and a few rust stains remaining, but I think it looks cool this way.
I also passed the blowtorch over the welds to see what it would look like.

Here's the results.

Image

Image

Image

I'll just give it a matte clear, and build it like it is now.
For those interested, the frame lost 50g after the stripping. It now weighs 2440g :shock: .

Louis :)

Color case hardening a frame: A Strip and torch job

Posted: Sat Jan 19, 2013 8:06 am
by Wingnut
I've got an Reynolds 853 road frame I was considering getting stripped too, then clear coating...saw one years ago, didn't look too bad from memory...

Re: Color case hardening a frame: A Strip and torch job

Posted: Tue Jan 22, 2013 2:26 pm
by 743power
"raw" frames have been popular in bmx for a long time. Unfortunately, even on a bmx bike which doesnt see anything more then dry dirt and road dust, the finish degrades and leads to massive rusting. Your project is the perfect bike to try it, but I wouldnt bother on anything expensive.

Re: Color case hardening a frame: A Strip and torch job

Posted: Tue Jan 22, 2013 2:26 pm
by Weenie

Re: Color case hardening a frame: A Strip and torch job

Posted: Wed Jan 23, 2013 5:16 am
by wally318
Your question referrs to case hardening. Which is usually done by dipping the warm metal
in some powder and then after bringing it to a cherry red quenching it into water or oil, depending on the alloy. The quenching will make the steel tubes quite brittle and loose
cro-mo's elongation qualities or fatigue life. Case hardening in pure metalurical sense
is usually done for wear resistance such as pins and bearing races.
The blow torch treatment and cooling will also weaken your frame by burning out more
carbon. In effect an annealing action.
For gun parts this is acceptable (case hardening), for bikes no.