K2 / Proflex Riders Group

General => Tech Forum => Topic started by: ReBeL on May 13, 2006, 08:32:17 am

Title: What type of aluminum is an 856?
Post by: ReBeL on May 13, 2006, 08:32:17 am

Hey guys!

What type of aluminum is a 96 Proflex 856 made out of?

I had my frame taken in to be welded up but they couldn’t do it because they didn’t have the right type of wire and it kept splattering so they gave up trying to fix it. I have a crack in the bottom of the head tub. Is the frame garbage?

Thanks for the help
Rick

Title: Re: What type of aluminum is an 856?
Post by: kiwi on May 13, 2006, 10:51:50 am

7005 tig welded?

Title: Re: What type of aluminum is an 856?
Post by: shovelon on May 13, 2006, 12:22:45 pm

Yep, 7005 self  hardening alum.  :)A decent repair will cost about $50.

It was problably spattering because of grease in the crack. [smiley=diaper.gif]

You have to bevel out the crack, remove the paint about 1/2 inch away from the weld zone. Using 5356  filler with no preheat, penetrate as much as possible from  the outside, then finish up on the inside with as little buildup as possible.

The weld shop should be using a 75/25 mix of argon and helium. If they don't know what that is, run.

After the weld cools, you can dremel or clearance the race seat to press in the lower cup. Do so, and let the bike sit for a week to allow proper stress relief, then go ride.

SAVE THAT FRAME!

Terry

Title: Re: What type of aluminum is an 856?
Post by: Oracle on May 16, 2006, 03:19:04 pm

Are all non carbon-fibre Pro-flexes (e.g 857) made from 7005 tig welded aluminium?

Title: Re: What type of aluminum is an 856?
Post by: shovelon on May 17, 2006, 03:18:13 am

Yep, 7005 is a high strenght, weldable, and self heat treating alum.

 The reason being is that the alloy is quickly self hardening as opposed to 6061 which must be aged hardened, either artificially or naturally. Naturally aged can take months, even years to achieve desired hardness and strenght. Artificial ageing is heat treating by heating and quenching in chilled water, and then deep freezing the part for many hours.

 7005 on the other hand because of the alloying elements that Easton chemists came up with, rehardens as soon as cooled. There still is a stress relief process of heating to 400 to 500 degrees for many hours, but most frame makers just powdercoat the frames and use that heat to mildly stress relief. Then the frames usually sit in assembly to shake out the balance of the stress. So 7005 comes out much cheaper to produce in the long run.

 The other nice thing is that weld repairing is a no brainer. After repair, the alum self hardens, you let it sit from a week to a month, and presto, you go ride.

Terry

Title: Re: What type of aluminum is an 856?
Post by: ReBeL on May 27, 2006, 03:25:12 am

Thanks for the help Guys!

Its at the shop getting dipped and welded!!!