Gdogpdx

Are there are any accepted fillers for filling small inconsistencies at a joint? Low temp solder or epoxies (bondo?). This notion of filling with anything other than metal makes my toes curl a little but this is not for anything structural only slight blemishes. I would be interested to know how other builders handle these types of things.

Thanks in advance.

Andrew R Stewart 

Many techniques exist to fill gaps, pock holes and dents. Which to best use depends. Does the filling need to be heat resistant like in powder coating baking? How about "sand" blasting resistant? Will there be any metal plating done?

Bondo is probably the easiest but not too durable to heat and abrasives. Solder works well too but is soft. Brazing filler is perhaps the best if there's to be blasting or plating done after. many builders will use filler rod as it's already there and who knows how the frame will be treated in the future. Andy.

Gdogpdx

I'm planning to paint this frame, no powder coat or plating involved. What solder, if any, will bond to steel without reheating the joint to full brazing temp?

Thanks in advance.

Andrew R Stewart 

Solder typically doesn't need the temp level of brazing. Common plumbing (lead based) solder only needs around 450*F. Clean all just like brazing, flux where you want the solder to stay and practice first. Andy.

unterhausen

I see no issue using silver brazing filler

Gdogpdx

I did a little experiment last night with a tin/silver solder on a scrap tube and made a nice blob no problem, with minimal heat. It files nicely, very hard and is definitely adhered to the steel.

ksisler

[SUP][/SUP]Ah...just saying; Pull the tube out and cut another one to fit better/correctly? The too-short tube can be recycled without loss for another later frame that is a cm or so smaller.

Sorry I digressed without understanding the context as you stated it.

Yes, as long as the area is cleaned well a bit of bondo can be wiped in with the tip of the finger to fill a little cosmetic blemish. This is probably covered in some other forum on "body work" for cars. A bit of filler is much perferred to attempt to reheat the joint and add more brass, imho.

fwiw; /K

MassiveD

The first or second welding job I did was new handles for my garden shed. The design consisted of angle iron to which I attached some rod. Made a very attractive handle, but more importantly a much stronger one than the plastic pieces one was expected to trust when secured with a padlock. The handle was nice, the welds where horrific. So I bondoed them with 5 minute epoxy and some microballoons. 10-15 years has gone by and the look is perfect, nothing has pulled away or cracked. I would not normally trust 5 minute to have the adhesion.

While there is a prejudice against fillers, one I share given the adhesion issues with steel, it is still pretty common to fair these surfaces. I would not do it on a customer bike, because of reasonable expectations, and the fact that frames work quite a bit more than garden shed handles, but I might try it on one of my own bikes. It seems to be cool enough to bond structures to metal these days, just not to fill pinholes. Admittedly there is a difference between wrapping a tube with carbon to take the load off, and filling holes. The wrapped structure is not going to spall off... But the the pinhole fix is not going to fail catastrophically which is not always my feeling about some of the carbon/Al parts...

MassiveD

I remember when this guy used to show up on Monster Garage. I love how he makes a living filling with lead, and that cigar is always there... I woul dhave died at 45 with that combo:

https://www.youtube.com/watch?v=jQ_85fp1avs



I didn't watch that particular segment, but I love how the guy's main fixtures visible in the opening segment are stolen milk crates!

MassiveD

"When they took the mercury out of it, it wouldn't work good..." Classic!

Cassave

I love watchin' old farts do their stuff.
Re-lit his cigar with the torch. LOL.

Mark Kelly 

Car bog seems to have worked well enough for Cinelli.