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Alutight for a fuel tank?
Slimy38 - 6/5/18 at 07:52 PM

So the only thing I came out of Stoneleigh with was a length of the alutight stuff that the Swedish guy has been selling for the past few shows. The reason is that it seemed like something to make a fuel tank out of.

Obviously the demo was only with small pieces of metal, and there are several comments about it being brazing or soldering rather than welding, but has anyone actually tried it on something substantial? Does anyone know what it actually is?

Oh, and on another note, now I've managed to get to a point where I could order a Healey body, the current mould owner is nowhere to be seen...

BenB - 6/5/18 at 09:08 PM

I'm assuming this is a friction stick brazing thing (same as Technoweld). If so I've tried it and it gives a strong bond but the issues are mostly related to the nature of aliminium- namely conduction of heat. You have to get the workpiece flipping hot (pre-heat in a toasty oven) otherwise the blowtorch heat just get dissipated and you stop brazing. The second challenge is trying to braze one fillet without your other fillets melting and the whole thing turning into a melty mass of flipping hot ali sheet.

I ended up rivetting the pieces together, the brazing then using a super fine super toasty blowtorch to plug the rivet holes.

It's quite tricky but if you manage it the strength is impressive.

Mr Whippy - 7/5/18 at 09:03 AM

could maybe cover the tank in fireproof insulation (rockwool) to limit the heat loss, but I have used technoweld before and it's best used for small items and we found the welds quite brittle when flexed

ianhurley20 - 7/5/18 at 05:34 PM

I've used a similar product to ?braze? aluminium together and the biggest problem is heat. It dissipates very quickly indeed. My torch will give 1600 deg C from normal fuel which sounds enough but isn't. I found that using two torches, one from each side got me to the amount of heat I needed for the thickness of aluminium I was using (about 1.5mm I think). I have been spoilt really by using oxy/aceteline and you can get a lot of heat in quickly and it works very well so the issue is indeed heat.
The guy at the show was using very thin ally when I went past him yesterday
When you need to replace the rods you have there are lots of overseas suppliers on ebay that sell rods cheaply that work as well

Slimy38 - 7/5/18 at 06:21 PM

quote:
Originally posted by ianhurley20
The guy at the show was using very thin ally when I went past him yesterday
When you need to replace the rods you have there are lots of overseas suppliers on ebay that sell rods cheaply that work as well


yep, I did wonder whether him just using small plates was part of the story. It was 1mm thick so it was the same thickness as I was going to use, but really didn't take much to heat up.

Thanks for the heads up on the alternative sources though, I wasn't in any doubt that it could be obtained in the uk but I had no idea what it was called.

MikeR - 7/5/18 at 06:28 PM

I've wondered if you could sandwich a rod between the two bits of Ali, then heat. It melts and joint made.

907 - 7/5/18 at 07:53 PM

Would you really be happy about 30 odd litres of volatile liquid half a meter from your bum
held in place with something susceptible to brittle fracture?



Paul G

ianhurley20 - 7/5/18 at 08:27 PM

quote:
Originally posted by 907
Would you really be happy about 30 odd litres of volatile liquid half a meter from your bum
held in place with something susceptible to brittle fracture?



Paul G


Paul - I must say I agree with you - I would want 3 mm ally for a fuel tank and don't think I could get the heat in the right place for it to work properly at that thickness. Using a TIG though.........
Good point.

I've used it to make things like a boot for my seven which are a lot less critical