head tube distortion Fillet brazing

[Tally]

Hi guys,

I have had a few issues with my headtubes distorting once I have brazed. I leave 15mm from the tube to the end of the headtube and I am using Reynolds 44mm headtubes.

At the closest point to the braze (so rear of the headtube along its centre line) the tube has 'pulled' towards the rear of the frame. This is leaving a section that is uncut once I have reamed and faced the headtube.

I am fillet brazing with no heatsink.

I would love some advice on how to avoid this please.

Thanks
Tally

[EricKeller]

You also need to heat the front of the headtube

[rellis]

What is the wall thickness on the headtube you used? Most headtubes intended for fillet brazing are 1.3mm and thicker. I have used standard 1mm wall headtubes with reinforcing rings with very little distortion.

[Tally]

Hi The head tubes I am using are 1.25mm with a 5mm deep 1.8 section on each end (like a reinforcing ring) from Reynolds.

I Haven't been heating the front of the tube so I will try that on a practice head tube and see what effect it has.

Would a heat sink help or would it then become to difficult to keep the heat in the steel?

Thanks for the advice, this forum is a goldmine of info!

Tally

[j44ke]

This might reach other experienced fillet brazers on the Mentor part of the forum.

[e-RICHIE]

Tally - Add a first and last name to all posts and comments you make and I'll move the thread to a proper board.

Thank you.

[Tally]

Hi Richard,

I will add my name, sorry I hadn't realised I needed to.

Thanks

David Tallontire

[Blacklabbikes]

"I Haven't been heating the front of the tube so I will try that on a practice head tube and see what effect it has."

1. Even heating - Add a bit of flux to the front of the HT to see when it's up to temp.

2. Make sure your mitres are spot on.

[cblandford]

David -

I have this thread bookmarked and printed for reference:
https://www.velocipedesalon.com/foru...ion-43211.html

You'll have to draw your own conclusions, but as someone new to fillet brazing, I've found it immensely helpful.

-Chris

-
Chris Blandford
blandford.chris@gmail.com

[progetto]

Speed and pre heat is your friend my friend.

[steve garro]

David -

I have this thread bookmarked and printed for reference:
https://www.velocipedesalon.com/foru...ion-43211.html

You'll have to draw your own conclusions, but as someone new to fillet brazing, I've found it immensely helpful.

-Chris

-
Chris Blandford
blandford.chris@gmail.com

Thanks for that link - I still think the same thing(s) !!

- Garro.