New/amateur/garage/kitchen framebuilding discussion.

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  • I don’t think I’ve watched any of his brazing stuff but I was watching his machining vids for a while. Also watched a lot of Abom vids and was cringing when he got the brazing torch out for a job and made a total arse of it.

  • Nice NJS frame in need of a Geoff Roberts style repair, good opportunity for someone if it stays cheap...

    https://www.ebay.co.uk/itm/Level-Njs-Tra­ck-Bike-Frame-Forks-Hatta-Swan-BB-Headse­t-Snapped-Seat-Tube/293492240971?hash=it­em445580324b:g:xVEAAOSw3fFeVaLE

  • was thinking about adding a disc brake mount to a 631 frame. Have small gas torch, flux, and silver solder of varying grades already. Think I've got the ability to align mount/file and braze it on without fucking everything up, and interested to try it, but equally could just fling it at a proper builder to do.

    Yea or nay?

  • Yea, do it!

    Take your time, but do it!

  • ha! might be 'fools rush in where angels fear to tread' but am keen to try it.

    the frame is fillet brazed so mostly worried about possibly fucking up existing joins-think clamping on some kind of heat-sink to the drop out/seat stay where the disc mount will be brazed on is necessary or recommended?

  • Assuming the frame is brazed using brass, your silver solder has a much lower melting point, so I wouldn't worry too much about damaging the fillets.

    It wouldn't hurt to order a second disk mount or just a price of steel plate and practice soldering it to something other than a bicycle frame. Just to get an idea of the type of heat you need to focus into the mount rather than the thin tube.

  • Just don't get anything yellow hot and your brass frame joints won't be affected. Silver will flow with just a dull red glow on the steel

  • That said, I'd rather be using brass for a disc brake personally...

  • good to know, thank you.

    Will have a poke about on ceeway and be sure to have a couple of trials on scrap before attempting anything!

  • is that because it's more appropriate to the kind of join, just because it's stronger, or both?

    I was going for the silver mostly because the melting point is lower and would be less risk to the frame, but if not appropriate then obvs will look at brass again.

  • It just flows like a much thinner liquid when melted so it is difficult to build up a decent size fillet so you'll have less surface area of filler holding it together.
    Doable though I'm sure

  • gotcha, thanks.

  • Any recommendations on a pipe bender. Mainly for racks. I have used one of those £10 copper pipe benders and it worked okay but was looking for something with a bigger curve radius and just a bit more versatile.


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  • Anybody interested by a small cracked Kona Smoke? Free pick up from KT6


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  • Hello forum framebuilders! I come in need of your help. Would anyone (in London) be prepared to have a stab at TIG welding over this crack in my chainstay? It's a Sirius 653 frame with 0.6mm chainstays.

    I spent aaaaaaages carefully removing the seized BB from the frame but then found this crack while prepping to repaint! Before removing paint it looked like a thin line of surface rust in the paint - from where the rear tyre rubbed the paint away - so I'm hoping the steel on either side is still near 0.6mm thick.

    I can do any prep work, bring the frame to you and offer beer / cash bribes / parts / whatever. My plan B would be a replacement 631 chainstay from Winston Vaz (£100), but it would be nice to keep the 653 (i.e. 753) chainstays and of course nice to save the £££.

    @Dogtemple gave me some useful info and suggested I try asking fabrication forms or posting on a welding forum but I thought I'd ask here in case anyone felt confident.

  • Im happy to do it in exchange for hipster beer, but there's no nice way to do it and no guarantee that it will stay together, itll be super dirty on the backside and with no way to clean it, the weld will draw all the crap into the bead, which is not good. I would go straight to Winston, chances are you will have to anyway. I dont do lugs so cant replace the stay

  • @Biggles567 Thanks for offering and for the info.

    Yeah it's definitely dirty on the backside. I could have a reasonable crack at cleaning the inside of the tube because there's access via the BB shell. So I could get busy with a ball of wire wool on a coat hanger with some Kurust and then repeat with some alcohol.

    But yeah if you tell me it's likely to fail even given that prep then I'll take your advice and go to Winston.

    I also had ideas to just lay up some carbon weave over the stay (I've repaired carbon frames before) but that feels more like a bodge at this point.

  • If you’re going to put any more effort into the paint that simply rattle canning it then get the stay replaced.

    It’ll probably need replaced in the end anyway so you’ll only end up kick in yourself if you don’t.

  • 1) You don't wanna be tigging that crack. 753 is a Mang Moly tubeset meaning it will become brittle as f*ck in the haz with tig.

    Get it fully replaced or it'll crack again.

    2) maybe more photographs are needed, but that doesn't look like the crack has progagated through cyclic loading ... it isn't a big sharp sawtooth shaped crack. In this location a fatigue crack would be expected. It looks more like you have some corrosion issues.

    Again, replace. Winston!

  • Well the consensus here is reassuring.

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New/amateur/garage/kitchen framebuilding discussion.

Posted by Avatar for M_V @M_V

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