Hi, Ive been following this forum for a while but this is my first post. My question is re making the chassis, as I dont have a welder I wondered about using that Chemical metal because it claims to be as strong as the metal around it. Ive searched on here but not found any info. Also, with regard to cutting the tubes, would a 9" grinder be ok or would this not really be accurate enough.
Your help would really be appreciated on this one.

Gordon

it probably depends on how you used the chemical metal. I dont know much about it but id be amazed if it passed the sva test.

9" grinder is a bit big for accurate cutting, maybe a hacksaw is more suitable?!

I once had the pleasure of seeing a roll cage joined with chemical metal, the scrutineer took around 3 blows from a sledge hammer to completely demolish it, that was diagonals, stays front hoop ...

This is not a realistic replacement for welding. It may be okay with static loads but will not last 5 minutes in this application.

I have 9" grinder, 4.5" grinder power hacksaw and plasma cutter, ended up using the humble 12" hacksaw with a decent blade.

Regards Mark

Hi and welcome,

do you mean you would consider using chemical metal to join the chassis tubes together instead of welding them?,

if this is the case the answer is easy....

NO,NO,NO,NO,NO,NO don;t even consider it, not in a million years


HTH

Ray

[Edited on 27/8/06 by rayward]

[Edited on 27/8/06 by rayward]

I agree it's a bad idea, but a test would be good to help convince yourself. Get a small tube of the stuff and "weld" two tubes together. Now have two identical tubes welded the regular way. Now either hit them with a big hammer or squeeze the joint in a vice. In either case, the joint should be able to be bent over on itself without failure.

Eventually someone will come out with some stuff that might work, but I suspect the problem will be with preparation. It's similiar to composite construction. If the chemical mixes, temperature, and surfaces to be joined aren't exactly right, it'll snap right off, as will this stuff you're describing.

Cable ties are the best. Nothing beats them. MY mate once was missing a few head bolts so we fastend 127 zip ties and it worked.




You cant do better then welding. Do what all the pros do is a good idea to take. Unless something is proven dont do it.

would probably cost more in chemical metal than you could buy a ready built chassis for anyway

Ray

JB Weld even has weld in it's name so that must be good as well and I've seen some adverts for wallpaper paste where a man was hung out of a helicopter pasted to a board, that wasn't you was it?

Dont do it

Get a kit and learn the bassics.

[Edited on 27/8/06 by big_wasa]

My sarcasm-o-meter has hit overload. He's a locost novice! Bet he doesn't post here again after that chunk of sarcasm!

come on jeremy beedle out you come

maybe i answered a little seriously then! I was thinking of being sarcastic but thought he might actually be serious, plus i suppose you probably could stick a monocoque together with the stuff!

Glue is fantastic stuff when used right. Glueing metal to metal jsut doesn't seem right. I know that Lotus glues its elises and I have even seen several chassis in the factory but I still don't believe it.

The only glues I have ever seen that don't break with hand force is PU adhesive on GRP and PVA on wood. The wood breaks before the PVA joint does on anything I've tested and I'd expect the GRP to go the same way before a good seam of PU.

Metal to metal joints? Solder braze or weld.

nothing better than getting burnt by welding. elbows hair and neck are the best. I learnt to weld building my car. I know my welds are good because iv had to grind them off when iv messed up.

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Originally posted by smart51
Glue is fantastic stuff when used right. Glueing metal to metal jsut doesn't seem right. I know that Lotus glues its elises and I have even seen several chassis in the factory but I still don't believe it.

The only glues I have ever seen that don't break with hand force is PU adhesive on GRP and PVA on wood. The wood breaks before the PVA joint does on anything I've tested and I'd expect the GRP to go the same way before a good seam of PU.

Metal to metal joints? Solder braze or weld.

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The lotus chassis is glued where sheet ali meets sheet ali on a large surface area. The glue is just used in copious amounts, thats how they make it work. Theres also a fair amount of big fat rivets.

As for the locost chassis, i think people think welding is just a glue....

maybe theyll come up with some kinda chemical weld which chemically melts and bonds the join??????

Thermite wil chemically melt metal.
But it might not be flaming hot enough for you know who.

Chewing gum may be a better alternative, after all, have you ever tried getting it out of a carpet..... It will not move for anything

The Aston Martin DB9 has a nice glued together chassis.

If its good for them its good for anything, just not for me thank you.

I would ask if brass brazing is an alternative to migging the chassis up?

Not sure what the technical term is, but cateringvan's are 'brazed' or something similar together. Not sure on the actual term, but it's not mig in the way most use it.

Bronze welding is the term least likely to evoke a flame war

Cateringvans are now produced by Caged so mig and/or tig welded. They only changed over from Arch Motors a year or two ago.

A good description of the process is in this book -> link <-

Not quite true...I hear Arch are still producing the majority of chassis. Take a look for threads on this on blatcaht.

They do already use thermite for welding train tracks together. I guess it oculd be scaled down a bit....

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Originally posted by stevebubs
Not quite true...I hear Arch are still producing the majority of chassis. Take a look for threads on this on blatcaht.

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It could just be that caged are having problems with Trevor the welder. He's a robot and may have not been set up right yet?

He looks to be going hard at it in this thread.

http://www.locostbuilders.co.uk/viewthread.php?tid=46376

Poor lad, hasn't even got a visor on!

Mike

Perhaps he's gone at it too hard and gone pop?! Is Trevor doing mig/tig or the 'bronze welding' in that vid that can be seen on the bare chassis?

Bronze welding is an oxy-acetylene process so it's not that

Looks like MIG to me.

So what's the golden coloured stuff on this chassis then? Not being picky/awkward, just curious.
Rescued attachment chassis1.jpg

Looks like bronze to me maybe they have a funky way of migging with bronze wire? That robot was certainly electrically welding not holding a torch.

Arch are always using gas torches in their pictures I've seen (green flames since they were adding flux to the gas).

http://www.archmotor.co.uk/history.htm

Later: Google shows it is indeed possible to MIG with bronze.
http://www.mig-welding.co.uk/brazing.htm


[Edited on 29/8/06 by iank]

Looks like that could be a trick worth learning.

Hmm.. after all that I'm still wondering about brazing. Does it put too much heat into the chassis

I know its more flexible than welding but is it strong enough?

The reason I ask is because I have gas bottles and no mig. Lots of brazing kit but no MIG kit.

I've also got an arc welder but thats something else...

On that website he cracks/bends a weld, but the steel breaks at the edge of the weld rather than the weld itself cracking. As for thicker stuff, I don't know what would happen.

It puts much less heat into the chassis, since the melting point of the filler rod is much less than steel. Thus very little distortion. It also means if you bend a tube you can remove it buy melting out the bronze rather than cutting and grinding.

Need to be careful with the term brazing since it's the name of the process and is often associated with using brass as the filler, which isn't up to the job of chassis construction. This terminoligy thing has caused flame wars on this subject before.

Try to get the 750mc book I linked above from the library (probably not worth buying just for the chassis costruction section).

You'll be lucky to buy a copy of that 750 book - last time I saw one on eBay it was going for stupid money!

It does give a very good description of the bronze-brazing technique, including how to set up the metal to create the strongest joints. It's quite a different technique.

The authors also illustrate the strength of the technique by describing how one of them piled into the end of the pit wall at 100+ mph and survived, protected by a bronze-brazed spaceframe!

quote:

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Originally posted by David Jenkins
You'll be lucky to buy a copy of that 750 book - last time I saw one on eBay it was going for stupid money!

...

The authors also illustrate the strength of the technique by describing how one of them piled into the end of the pit wall at 100+ mph and survived, protected by a bronze-brazed spaceframe!

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quote:

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Originally posted by Locost Novice
it claims to be as strong as the metal around it

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quote:

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Originally posted by iank
He only just survived that crash, needed his heart restarting by on track guys IIRC.
The spaceframe survived extremely well IIRC, but the body just can't take that kind of deceleration.

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Originally posted by mcerd1
brazing is better than the glue stuff, but you'd be as well to borrow, hire or buy a mig - its far stronger as well as easier to do

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It's worth bearing in mind that bronze-brazing isn't the answer to life, the universe and everything.

The bronze rods are quite expensive, joints have to be far more accurate, the parts need to be cut and shaped differently when compared to welded joints, and cleanliness is paramount. You also have to deal with oxy-acetylene and flux.

I wouldn't mind giving it a try though, as I've done loads of silver soldering in the past and the technique isn't so much different.

David

quote:

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Originally posted by David Jenkins
It's worth bearing in mind that bronze-brazing isn't the answer to life, the universe and everything.

The bronze rods are quite expensive, joints have to be far more accurate, the parts need to be cut and shaped differently when compared to welded joints, and cleanliness is paramount. You also have to deal with oxy-acetylene and flux.

I wouldn't mind giving it a try though, as I've done loads of silver soldering in the past and the technique isn't so much different.

David

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Sorry - didn't mean to lecture you!

Just trying to give everyone a clear picture of bronze brazing... it's not a simple and easy alternative to MIG welding, as it has its own skill requirements, and 'ups-and-downs'.

[Edited on 30/8/06 by David Jenkins]

I brazed my sump pan together when fitting my zetec. Tricky to get right when learning but once you get the knack it's great.

Steve,

I guess that's ordinary brass brazing, rather than bronze brazing?

David

I've done what I thought was "brazing" before, but know I don't know if it was or not! I used an oxy-acetylene torch with brass coloured rods and flux, the steel had to be heated red hot to get the brass/bronze to melt and fuse the joint together.

Brass runs like solder, thinly coats the sheet.
It's used for capillary joints, i.e. tube slid inside another tube.

Bronze forms a weld bead, hence it's called bronze welding.


Not to be confused with silver solder which is, as far as surface tension is concerned, a little more bead forming than brass.


Confusing ennit.

Paul G

Yup! This definately formed a proper bead, was used to join some chassis members on a kart I built years ago.

Might be just me but I think brazing is easier than Migging! You have more control and can see easier whats going on.

Thanks everyone, I was meaning brazing with brass rods but didnt realise bronze brazing was stronger.

I have gas bottles here but no MIG welder so thats why I was asking.

Cheers
Steve

Has anyone used TIG for bronze welding or brazing? I would like to know the trick to this so I can retire my oxy acetelene kit

TIA

Caber

quote:

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Originally posted by coozer
The Aston Martin DB9 has a nice glued together chassis.

If its good for them its good for anything, just not for me thank you.

I would ask if brass brazing is an alternative to migging the chassis up?

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Brazing can easily be stronger than fusion welding. The secret is the surface area.