Built a larger fuel tank for my boat

Ed.

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Another part competed, needed to put in a larger fuel tank in the boat, old one was 200lt new one is now 330Lt, went down to my local scrap metal recycling yard and picked up 2 sheets of 2.4 x 1.2mt aluminium 5083 H116 sheet, didn't know it at the time but one was 4mm and the other 5mm thick, (was after 4mm for both), anyway went to a sheet metal shop to try and fold them but because of the its temper when we tried to fold a test bit, it cracked in half, so new plan, we made a series of 6 part bends to get the curve on the corner. So the tank has two straight 90 degree joints and 2 radiused bends. 2 baffles on the insides, made the 5mm plate on the bottom and one side and also the ends caps. 4mm plate for the baffles. Incidently the reason I used that thicknes of sheeting is that I could only buy new 3mm sheet at 1.5 to 2 times price of the 4 and 5mm sheet from the recycler place,

Machined up a short 50mm Aluminium tube for the inlet, welded it to a square piece of 5mm plate though a hole and then welded it to the inside of the tank end though another hole. A bit of 10mm tube for the outlet at the top, same thing, though a hole in a square plate and then again welded to the inside, a bracket 3/4 of the way down the tube to sop it vibrating and fatiguing to connect the tube to the wall of the end cap.

One inspection hole from 5mm welded to the outside which has a 7mm plate with 8 of 6mm screws to hold it down, a hole for the fuel sender, this was made on a piece of 16mm plate as I needed to raise the height of the sender due to the type I used, being made in certain sizes only. (300mm or 350mm with nothing in between). The type of sender I used is a reed type, ie; a floating round float which goes up and down around a S/S tube, unlike the other type which has the float which pivots on an arm.

The other end has just one air outlet which I machined from a bit of 16mm aluminium round and welded the same as the other connections. The reason for the overhang on the bottom plate is to allow some screws to lock it down to the floor of the boat so it wont move when under way.

Although my TIG welding sucks, I feel reasonably confident that it will be leak proof but I still have to give it a pressure test to see if it leaks, better now than after it has fuel in it.

Baffles 1 IMG_0761.jpg Baffles 2 IMG_0757.jpg Fuel outlet IMG_0770.jpg Fuel tank breather end IMG_0809.jpg Fuel tank Inspection and  sender hole, intake and outlet tubes IMG_0801.jpg Inside fuel tank weld IMG_0771.jpg TIG weld on end IMG_0803.jpg
 
Ed,
That is some great work. I wish my aluminum passes looked half as good. What equipment are you using?

Randy
 
Thanks guys, Randy, the machine is an Everlast 256 and set at at about 130-150 amps pulsed, 2.4mm 2% lanthanated electrode 2.4mm 5356 filler. I was hoping to do it with my MIG but for the life of me I cannot figure out why my MIG doesn't weld Aluminium to my satisfaction. I spent about 4 hours varying all the settings, going from one extreme setting to the other and it would not do a weld I was happy with, so for the time being I just gave up and used the TIG but the MIG would have been about 80% quicker.

Cheers

Ed.
 
Ed nice tank, The problem with mig welding Aluminum is that it doesn't push very well. What you need is a spool gun to do Aluminum with.

If you know someone who has one see if you can try t you'll really be surprised.

Paul
 
Thanks Guys,

Highpower,
The shielding gas I use is straight argon.

Old iron,
the spool gun isn't an option for me because of my MIG, it is a Miller Auto Invision 456 which was designed as a power source for a robotic welding machine, to get it to work as a basic welder I had to have the top circuit board, which controls the robotics disabled along with all the bells and whistles and the wire feeder cable is connected directly to the internal loom, this was because on this model there was no provision for a normal wire feeder to connect to it on the outside of the case. However I do know of and have seen results of spool guns but as I said I don't have the option.

Today I went over to one of my mates place and played around with his Kemppi Fastmig 350P which is a pulse machine, and did some welds with the synergic pulse settings on and also off, didn't have any problems with either through his normal MIG torch, in fact I preferred the pulse and synergic off welds I did, I like the smooth hot glue look if you know what I mean, but getting back to mine I think it is something simple that I am missing or is going wrong, whilst I was over there, I was trying to narrow down the causes, at least it wasn't my welding technique which is a relief. :biggrin: . But there are 3 possibilites left which I hadn't considered, the teflon liner which is new,the new roll of wire which I bought and lastly the torch I assigned to use for welding aluminium is a NB35 binzel type with a Euro fitting which is plugged into a converter to use on the Miller S-74 , I don't really think that it would be the wire and more likely the liner but I now highly suspect the Euro fitting converter as it has a copper/brass inlet which may be scraping and slightly jamming against the Aluminium wire as it goes though, you never know it might anyone of these or all together. I will play around some more over the next few weeks when I get some time to spare. I think I will get a new teflon liner for my normal Tweco #4 torch and remove the converter, however that torch is about 4 meters long so that may also cause problems. Will keep you guys posted if I get good results.

Cheers

Ed.
 
Ed, what size of tip did you use on the MIG torch. Since aluminum expands more than steel when heated, you need a larger hole in the tip than you would use for steel wire. The expanding wire would tend to jam up soon after you got started with the 'normal' size tip.
 
Ed, what size of tip did you use on the MIG torch. Since aluminum expands more than steel when heated, you need a larger hole in the tip than you would use for steel wire. The expanding wire would tend to jam up soon after you got started with the 'normal' size tip.

It was the 1.2A which is the one designed for that size aluminium wire, I drilled it out a bit as well but didn't seem to make any difference, so I still suspect the problem is between the tip and where the wire leaves the rollers, with the converter looking like the most likely culprit.

Ed.
 
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