Topic: Braze it or MIG it

[mick7504]

I've had to replace the rear foot peg holders that were a bit mangled up on a 750 frame.
What I did was to machine some round bar slugs to fit inside of the tubing and lock it all together to keep it squared up.

I'm leaning towards brazing because I reckon that it's going to be strong enough with the round bar inside.
Any thoughts?

[AJK]

That would be a neat repair the way your've done it with that solid internal support. I'd be erring to braze it as it would likely flow better on the inside making for a more robust joint. That said, mig would work as well but i'm thinking you might have to V-groove your posts a bit more if you go mig.

[trueblue]

Mick, I would lean towards the mig, but I would turn the heat up to ensure you get penetration through into the slug.  I can't see why brazing wouldn't work though.  It should be strong enough, but you would want to ensure you have good flow onto your slug.  The one in the pipe, you don't want to flow braze onto your other one .

[mick7504]

Mostly I'm thinking about having a clean finish when it's done.
Another idea which is probably overkill was to run a 3/16" drill in a couple of places through the tubing and spot weld  the slugs with the MIG and then braze the joints.

The 2 longer slugs are a wisker smaller than the other 2 so that they can be pushed right into the peg holder and then tapped through into the frame tube when it's lined up.
They're still an interferance fit but can slide inside with a few knocks.

[calj737]

MIG or TIG. And do drill thru and weld fill it for full and proper strength. Leave the brazing for non-stress bearing elements.

[faux fiddy]

If the brazing  doesn't work you have to clean off all the material involved before you try to weld , which could be a serious drawback to using brass.  It might herp to get the slug good and hot with a torch before you start welding.

[754]

Please drill out the slugs to same wall thickness or thinner, they will concentrate stress in that area.  I would not plug weld the sides, absolutely unnecessary. And. Way more cleanup in this application ..
 I think brazing will be quicker cleaner, faster. Job..

[Steve F]

If it was mine, I'd TIG it with a 1/16 mild steel rod to fill the groove and smooth it down after with sanding disc.
I'd also do the drill and rosette weld about an inch away from the weld joint.

[TwoTired]

Please drill out the slugs to same wall thickness or thinner, they will concentrate stress in that area.  I would not plug weld the sides, absolutely unnecessary. And. Way more cleanup in this application ..
 I think brazing will be quicker cleaner, faster. Job..

This would get my vote.
 The plug is going to suck a lot of heat away from the join.  The brazed joint will be stronger than the original tube.  I'd worry about stress cracking if welding with steel alloy rod, unless you heat the frame components near to welding temp during the weld.

[Ichiban 4]

Before there was MIG or TIG..all bike frames were brazed at the various connection points.  When I worked for a Schwinn dealership (who at one time also made Henderson and Excelsior motorcycles BTW)..a good brazed frame would break somewhere other than the braze joints..before breaking at the braze joints.  We also used to test the braze joints by periodically putting them in a stress press..to see how much force it took to break the braze.

Point I'm suggesting is..that brazed joints..reinforced by sleeves or lugs..can be stronger than parent metal.  The limitation to brazing nowadays is the extra time and equipment required to do a good job (some requires pre-heating and "tinning").  But that's more of a production consideration nowadays..not quite so critical for us wrench monkeys..I suggest..

Cheers

Ichi

[mick7504]

I've bored out one of the slug/inserts.
The wall thickness is .08mm less than the frame tube wall thickness and I'll braze them in which will give it more than enough strength for a foot peg/muffler mount.

Thanks for your help and suggestions gents.