How to blank off a hole in a barrel?

[goodolpete]

I bought a 50 litre blue mango chutney barrel off eBay as a beer making boiler. I successfully installed two kettle elements through 30mm opposite holes, then I went to drill a 20mm hole for the tap. This went wrong, leaving me with a

20mm x 30mm oval jagged hole. I need to blank this off well enough for it to stand 90 min boiling without leaking. Any ideas please how to blank off this hole in a 38cm diameter barrel made of roughly 3mm thick brittle plastic? The other alternative is to buy another barrel and kettles ruining a lot of work, which I don't want to do. TIA, Pete

[Huge]

It will almost certainly either melt or taint the contents. Throw it away & buy a Baby Burco. I have 2 of these;

[Richard Conway]

I would go for a 1" BSP blanking plug and a backnut like so:

and

The major thread diameter of 1" BSP is around 33.25mm so you'll have to make your hole bigger (and don't mess it up this time!) You'll need some kind of washer on whichever side you put the blanking plug on (I'd probably put it on the inside) - you can cut one to size from a silicone baking sheet that will happily withstand the temperature.

Hav> I bought a 50 litre blue mango chutney barrel off eBay as a beer making boiler.

[TomSawer]

[Richard Conway]

There's plenty of folk have used these barrels for brewing although I agree some element (no pun intended) of caution should be taken. For example I'd be reluctant to use one in the house in case it did go during a boil! A 50 litre stockpot can be sourced fairly cheaply on eBay as can 3kw elements and q max cutters for making the required holes. That'd be my recommendation.

[Richard Conway]

Well one would assume mango chutney would come in a food grade barrel :)

[Roger Mills]

Indeed. But he may have been referring to the plastic used for the repair.

[TomSawer]

Quite so - but plastic fittings for other purposes may not be.

[Tim Lamb]

Couple of big stainless washers, 2 *food grade* sealing discs (old inner tube?)

Stainless bolt through the middle.

[Brian-Gaff]

I've never successfully managed to plug holes in plastic containers as the flex and the glue often cracks and leaks. I'd imagine heating it will only make this problem worse. You don't say where the hole is, if its on a flat part then making the hole bigger and inserting a fitting of some sort might work, but if its on the outside, forget it. Brian

[goodolpete]

Thanks for all replies. Richard. Bought these components from ToolStation. I will buy a "PTX Bi-Metal Holesaw (Dia) 35mm" from B and Q. I already have the central drill for this, but obviously there is no material for the central drill to go through, so the 35mm bit will just hit the plastic full on. Have you or anyone any suggestions on how to make this a successful operation, as I can see the drill slipping about and making an even bigger hole in the side of the barrel.

[Tim Lamb]

In message , goodolpete writes

IME hole saws tend to make an overlarge hole in thin material.

Often because the pilot drill flutes are trying to support the hole saw teeth rather than the drill shank.

Perhaps you could wedge (hammer in) a roughly shaped plug to suit your bodged hole and use that as a hole saw support.

Somewhere in my accumulated tool store I have a kit for creating holes in plastic water tanks. After drilling a pilot hole you fit from inside a threaded disc which is larger than the intended hole and has a circular groove to match. An external threaded spigot secures this to the tank side. The cutters are similar to a hole saw but with many fewer teeth and, guided by the spigot, rotated by hand to cut the hole.

[Roger Mills]

Can you get at the inside of the barrel? If so, fix a piece of wood across the hole, and use that to guide the pilot drill.

[Chris Hogg]

You might be better off with a chassis punch, aka knock-out punch. Much easier to control than something whizzing around on the end of a drill. Slow, steady pressure. All you need is an Allen key to tighten.

[Syd Rumpo]

Use the holesaw on a piece of wood first - say 1/2" ply - then hold/tape/clamp this large hole over the plastic to guide the hole saw by its blade instead of its pilot drill.

Cheers

[Peter Andrews]

Use a carpet blade (the hooked one) in a stanley knife, easy to cut any size hole over 20mm in a plastic tank.

Peter

[stuart noble]

+1. It's what I used many moons ago. A doddle to use and not expensive, but what the hell was it called?

[Richard Conway]

Sounds like a q max cutter more usually used for punching holes in metal: