I want to cut a hole in a metal petrol tank.

[rustic]

I want to cut a hole in my boats' metal petrol tank, to fit a fuel gauge sender in.
The hole needs to be 43mm diameter.
I was thinking of using a rotary hole saw.

BUT:-
Saw + Metal = Sparks + bang :eek: :eek:

I thought I could empty the tank and fill it with water to remove ALL traces of petrol and vapour.
Then drill the hole even under 1/2 " of water above the tank, as long as I don't electrocute myself. :eek:

I looked on youtube, several people do similar, has any body tried this and survived.
The tank will be taken off the boat and done in the open.

While looking on youtube, I found this clip of a guy mig weding a petrol tank with fuel in it, he did put some carbon dioxide in it first.
So I don't trust many things on youtube, but this is suicidal..


http://www.youtube.com/watch?v=aOqgDaV8UR4

Health and safety would panic if they saw just some of the things he did :eek::eek:


Any advice please.
best regards,
Rustic

[zippy656]

try a plumbers centre, ask about a tank cutter.

adjusable has small centre drill and a n arm the cuts the hole.


http://cgi.ebay.co.uk/Priory-201-C-Straight-Shank-Tank-Cutter-4in-/300361743859?pt=UK_DIY_Materials_Plumbing_MJ&hash=item45eef47df3

others are about too, just to show what i ment

[(RIP) PLANK]

I would drain it, leave it empty overnight and then use a hole saw, I have drilled holes in empty propane bottles with a hole saw and you can't wash them out! i'm still here, though my eyebrows aren't! - not just joking, a day evaporating and it should be fine, i would steer clear off water in the tank as it will take a lot more to get rid of it!

Though i knew a bloke called Gus in devn years agon and he reconned he had welded many fule tanks using the co2 method and he had a lovely head of curls!

so maybe before you start blast a wiff of mig welding gas in the tank if you have any!

[Peasgood]

Usual trick when welding petrol tanks is to run a pipe into it from an exhaust at the same time. Same as the CO2 method I guess.
And you can wash propane bottles, just unscrew the valve assembly. Although that bit is easier said than done.

[solarman216]

If you do not have co2 then fill it with water to be safe, hole saw is OK but in thin metal they tend to make an over sized hole, as they only center in the pilot drill which even if not on the cutting flutes still wears quickly into a larger hole so allowing the cutter to wander, I usually cut at an angle, break through about a third of the diameter then gradually straighten up to a little less than vertical on final break through, I have gas welded diesel tanks with fuel in them with no problem, but would not trust petrol, likewise have cut old propane bottles with disc cutter but full of water first, when you have done empty the water out and place it somewhere warm is will soon evaporate, Rick

[rustic]

Thanks for all the replies guys, I have some Co2 for my mig, never used it yet, as I have only used the gasless wire.
I also read that to get rid of water to rinse with meths, and then dry as this will seek out the water.

So it looks like a green light.
It will be a few weeks before I do it, I'll advise how I got on.
If I don't renew my membership in February...... don't ask.. :doh

Thanks again.
regards,
Rustic

[(RIP) PLANK]

And you can wash propane bottles, just unscrew the valve assembly. Although that bit is easier said than done.

you can also wash them by cutting a hole in the side with a hole cuting saw first :augie

[tezzer]

does the tank have another hole that you can get your hand into, if so you need a 43mm tank cutter, 2 pieces of steel that bolt together, as you tighten it cuts hole, no sparks, you could even do it with fuel inside if you wanted, i do have few cutters but not 43mm, sorry. :thumb2

you could ask at a plumbers merchants.

[rustic]

does the tank have another hole that you can get your hand into, if so you need a 43mm tank cutter, 2 pieces of steel that bolt together, as you tighten it cuts hole, no sparks, you could even do it with fuel inside if you wanted, i do have few cutters but not 43mm, sorry. :thumb2

you could ask at a plumbers merchants.

Good idea, but the 43mm hole will be the biggest hole when done, with the hole punches you still need to drill a 6mm hole first.

[tezzer]

Good idea, but the 43mm hole will be the biggest hole when done, with the hole punches you still need to drill a 6mm hole first.

yes you will need to drill a hole first, but use a cordless drill and there wont be any probs, but if the 43mm is the biggest hole, then it's back the drawing board.:rolleyes:

[(RIP) PLANK]

i know im thick but, a two piece hole cutter that bolts together, you tighten the bolt and it trims a hole like a set of round tin snips? i have some in my shed.

but how do you get the half on theat goes inside the tank? you cant put your hand through the 6mm hole?

no a hole cutter is the way, go a couple of mm under and file it to precise size!

[tezzer]

thats why i asked if there was another hole, as you say cut smaller and file to size. :thumb2:naughty

[(RIP) PLANK]

thats why i asked if there was another hole, as you say cut smaller and file to size. :thumb2:naughty

ok i've read it now! :doh and i don't have one of those punch thingies anywhere near that size so i can't help.