Manitou clinic

[cimmerianbloke]

I found this website where a French guy actually got a broken Manitou HT frame for 50 euros and got a welder friend to fix it. Not bad considering most secondhand Manitous would have some kind of damage, and knowing that at such a price, there is little chance to have a decent aluminum frame for sale...

http://amiral44vtt.free.fr/manitouHT.php

 

[hydorah]

Cool

Sounds like a good score

Although I hope he got it heat treated afterwards

Did you know that welding destroys 80% of the mechanical strength of Aluminium

For example 6061 T6, after it has been welded is reduced to the stregth of basic 6061 approximatel 3 cm in any direction from a weld

But heat treating (or years of aging) will restore the original strength

If you're feeling geeky; Read this:

http://www.pinkbike.com/news/article1117.html

 

[BoyBurning]

Is it actually possible to 're-heat-treat' an aluminium frame though?

BB

 

[BoyBurning]

Is it actually possible to 're-heat-treat' an aluminium frame though?

BB

 

[hydorah]

Is it actually possible to 're-heat-treat' an aluminium frame though?

BB

It is yes

Afer repair, heat and quench just like first time

 

[B3]

Manitou frames are made from 7005 Easton program tubing, this is the choice of a lot of the niche brands of the 90's as 7005 doesn't have to be heat treated after welding, it can be artificially age hardened by heat treatment to speed things up but this is only to save time. If you left it a few weeks it would do it itself.

 

[marin man]

That was a good buy for him but a very....erm........lumpy repair it is.....does it really need so much....meat :?

 

[sunchaser]

Repaired aluminium frame, hmm.. it's cheap for a reason. I'd avoid it like the plague.

 

[hydorah]

Manitou frames are made from 7005 Easton program tubing, this is the choice of a lot of the niche brands of the 90's as 7005 doesn't have to be heat treated after welding, it can be artificially age hardened by heat treatment to speed things up but this is only to save time. If you left it a few weeks it would do it itself.

Age hardening does happen natrually but this is over YEARS

All aluminium alloys lose the larger percentage of their stiffness where welded because they are locally annealed where joined

This is local heating to melting point to fuse material

This causes the structure of the material to lose existing bonds, to align uniformly, aiding ductility but killing tensile strength and stifness

Heat treating is is high temperature (but nowhere near welding), uniform and is followed by quenching

Which looks the structure of the material in a more random orientation of bonds - Hard and strong to a controlled degree

Read about age hardening here:

http://www.keytometals.com/Article39.htm

"In contrast to the relatively stable condition reached in a few days by 2xxx alloys that are used in T3- or T4-type tempers, the 6xxx alloys and to an even greater degree the 7xxx alloys are considerably less stable at room temperature and continue to exhibit significant changes in mechanical properties for many years."

 

[hydorah]

That was a good buy for him but a very....erm........lumpy repair it is.....does it really need so much....meat :?

haha awesome! I just looked at the pictures, I was only talking about the mettalurgical principles

Didn't really look at this specific repair

I think with the amount of 'meat' on there it ain't really so much of an issue!!

Certainly won't be as strong as it was, though

There are loads of cheap '90s trend hopping bikes that were aluminium in some cases even '7005' just fabbed up then assembled, not heat treated back up to 7005 afterward

Plenty still running about the streets