[Closed] Flattening tubes/bars (metallurgy content)

I'd be happy doing exactly that. I assume it aluminium rather than steel? Not that it really matters other than bashing the paint off. I also guess you'll not be putting silly loads on it.

Aluminium "work hardens" when hammered and thus is more prone to stress fractures. To normalise the worked item you can heat it to the point where if you stroke it with a match stick (not the red end), it will leave a black mark.

Squashing with a vice (if you have a decent one) might work better? Depends on the strength of the tubes though.

solid bar - id be more likely to file it flat again.

ps vices are not presses 😉

Yah but most people lack presses. Kind of skeptical about it being solid myself otherwise I'd say yeah grind it flat.

If it's a car rack, probably pretty unlikely to be solid bar. I'd go for squishing it in a vice - more controlled and you run less risk of crumpling.

ps vices are not presses

Aye, but in 20 years I've yet to kill a vice by using it as a press 😉

I read its a pannier rack no molgrips ?

I have broken the bottom off a record one tonne using it for inappropriate pressing :/ boss wasnt too chuffed.

See when it lets go make sure your feet aint under the vice, it lodged its self into the osb floor.

Got access to 50 and 400 tonne hydraulic presses now 🙂

Ah, I was thinking car rack for a hybrid car 😉

In that case yes, probably solid alu, vice won't do it.

Yes, pannier rack. I thought I was posting to the bike forum 🙂

I could file it flat, but I'd be worried that I'd lose too much material because I think the flat section is wider than the bar/tube. Other option is to cut a section out halfway up and re-join it with an internal tube if it's hollow. Or an external one if it's not. That's probably better and easier isn't it?

I think it's likely to be hollow since it's quite fat rather than the traditional skinny job.

Whatever option you decide upon, please sit down and think !

Is the outcome going to add value ?
Are you aware of all associated risks and can they be eliminated ?
do you have a regression plan if things wrong ?
Finally ensure you have the correct equipment before you start !
Good luck

please sit down and think

I spend all day doing that 🙂

The rack is spare, since it doesn't fit well enough on any of my bikes. Well, it fits but because of the aforementioned size issue it's too wobbly for any decent weight.

I have been using a Blackburn Mountain rack instead which works better because it's smaller, but it's quite weedy and now I've fit all my gear on the rack instead of my back it's wobbling a bit too.

molgrips - Member

I think it's a solid bar

Ah.

molgrips - Member

I think it's likely to be hollow

Ah.

TBH you can't really plan a thing til you know, too different and what works for one will either not work at all or trash the other.

Yeah I don't know do I?

I'll pop down to the garage but I don't know how to check other than saw it in half. I think my cut and shut idea will work regardless though, just have to use an internal or external sleeve depending.

Should be able to get a good idea by tapping it and listening/feeling, does it clonk or bong. Out of luck if it blonks though.

I reckon, if it was me I'd try and squish it first, because if it's solid, that'll just do nothing while most of the other options will be trouble if its the other way round.

Just set about it with a hammer, what's the worst that can happen?

It turns out to be an ancient arcane bell which, when rung, summons The Dark One from his infinite prison.

Just not risk assessed this have you?

Just not risk assessed this have you?

I once set my own hair on fire with an oxyacetylene torch, and I have a big scar in my ankle from trying to take a jumper off while riding no-handed. Does that answer your question?

Lol 🙂

If it's alluminium, make sure you anneal it first to soften the material and avoid work hardening it (and cracking it)

(you need a blow torch, a bucket and a bar of soap to do this)

This is the rack:

[img] [/img]

It appears to be tubular, the flat part seems to be stamped on with a die. The ideal place for the new hole is just where the first weld is, which is of course not ideal.

However, if I position the rack exactly where I want it, the existing holes line up perfectly with the chainstay, about 2" before the dropout........ Looking at P clips now. Crazy?