I am a frame builder AMA

Thanks for the replies!

Yes I think the tube has thicker walls than the frame I will eventually torture, so that should be easier I guess.

I think I just need to practice more. Good to know that the metal needn't be glowing red for this to work!

What kind of flux would you recommend?

Thanks!

Either of these.

The green what I started with and it’s fine, bought the blue one quite recently on the recommendation of another builder. He reckoned it’s more resistant to burning up than the green one. Don’t know if I’ve particularly noticed.

Can’t remember what they cost, £20-30 maybe? Last a long time though so it’s worth it.

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Having tried both, I'd also recommend the stainless light flux over the system 48

Yeah, Good idea. I know a few welders so this could be easy enough.

Its a shame the local framebuilder just shoved it off and didnt talk solutions.

Hi Tube Wranglers
Anyone have an idea of what frame builders there are in London?
Stayer?
Varonha
… help

Haiku bikes? Jim is great

Spoke to a welder I know - said he would weld the bridge back together no problem for me once I've straightened the frame.

Shame the actual "framebuilder" at the local shop wouldn't bother or think of solutions considering that is his ACTUAL JOB

Thanks

Please any more names gratefully received

This website is a great resource for soldering and brazing. They also have a book that is very informative, and sell the consumables. Just knowing you 100% have the right flux and rod is half the battle won isn't it.
https://www.cupalloys.co.uk/

Not sure where to post so hopefully I can get a little guidance here - I have a genesis day 02 (7005 aluminium) with a little crack at the bottom of the headtube. From what the internet tells me, 7005 can be welded a lot easier than 6000 series alu can - was just wondering if anyone could give me a ballpark on what this would cost me and if anyone magically knows of someone near Kings Lynn capable of the work…

It's quite hard to get firm information about heat treating and repairing aluminium amongst the non-facts and guesswork that circulates - particular filler rods etc.
I was once given an incredible booklet from a place that did some heat treating for me, I'll see if I can share it.

I can weld it and have a powdercoating oven that can go to 250deg big enough for a bike frame, so can do some of the flavours of heat treating if needed, but it's expensive to run a big oven these days.

If you want a quick weld, it'll only take 10mins while you wait. (I'm the other side of Norfolk) - it'll probably be fine. It just need a good clean up in that area first. Most metal workshops could do that for you. I guess they'd want anything from £20-50 depending how stressed/friendly they feel.
But offering a warranty would be alot more expensive for it to be worthwhile.

Not sure it this belongs directly here, but looks like people have answered similar! I managed to destroy both my axle and dropouts by sucking in a rock during tracklocross (a week after powder coating).

I have access to TIG (and limited experience) and was wondering if anyone had any tips re. settings, or insights into penetration - aesthetic side I do not care about at all, and due to the cost of the frame a 'proper' drop-out replaement is not really worth it.

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It would be difficult/impossible to TIG a joint that has been brazed before, the brass has a lower melting point so burns into a mess before you pool the steel. The whole thing becomes a contaminated faff.
You'd have to remove all traces of the brazed brass filler first which may not be possible without cutting open the tube etc.

So best to braze it again really.
You could DIY braze it, but it's quite pricey by the time you've got gas and a torch for a single repair.
Go for it though! You'll be brazing a complete frame together before you know it 💪🌞

Framebuilding studio share - found on FB Marketplace - I have nothing to do with it

Link: https://www.facebook.com/marketplace/item/155196310967968/

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How do people get an oval mitre on the canti bosses to go on the oval profile of the forks? I bought the 3 types in the attached pic from ceeway and the oval ones (J+3 and J-3) kind of fit but not all around, which I would like.

I worry that if I start dremeling and fileing freehand that i might get them to fit but they wont be identical.

I could get the workshop at my work to toss them in the wire eroder but for that I would need the exact profile of the 531 fork legs in cad. Not impossible I guess, but not my preferred choice...

Any ideas? Thanks guys in advance!

PS I think this is a silver soldering specific problem, the gap is likely small enough that you could bridge it with a brass fillet

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Careful filing. It's tricky but it can be done.

damn, sounds like I just need to muster up the patience...

Thanks for your answer!

It worked!

Gotta say it's a bit addictive...

@M_V, when you make stainless racks, do you also use 10mm OD and 8mm ID? Is soldering stainless any different from regular steel?

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Is soldering stainless any different from regular steel?

You have to use silver rather than brass for the brazing so it all happens at a lower temperature. And is much more expensive. But it's basically the same. If you're fillet brazing with silver I'd recommend Fillet Pro brazing rods.

Use 30% silver. It's much cheaper than 55%

Par exemple

https://www.cupalloys.co.uk/store/430-Silver-Solder-1-5mm-dia-x-500mm-5-Rod-Pack-p276411675

ah good shout! I used38% for the canti studs and it flowed just fine.

Silver brazing and stainless is not a great combination when exposed to chlorides. Intergranular corrosion is a real thing and tends to unglue the joint over time. A decent coating will slow or halt the deterioration.

I am interested in this. Have you got some literature or links to back this up? There are quite a few framebuilders out there building with silver fillets on stainless steel tubing

A friend of mine was doing winter 600km brevets in northern England on his midlife crisis bike, fillet brazed stainless (eutectic silver). After it came unglued a couple of times, he consulted with the metallurgists at his work. Their response was that palladium was the correct brazing material to absolutely avoid intergranular corrosion but brass was better than silver.

His bike manufacturer started clearcoating their stainless bikes and that seems to provide enough protection. A couple of other UK framebuilders have swapped from silver to brass after some of their frames came unglued. No issues with brass that I know of, other than increased heat distortion.

Have a chat to Reynolds.

Can brass do stainless to stainless but not stainless to ferrous?

Isn’t it something like really stainless stuff you can’t do with brass but ‘stainless’ cycle tubing has so many impurities (or something) in it that it does work?