Enlarging "reaming" sink hole in kitchen basin

Forums › Home Workshop DIY › Enlarging "reaming" sink hole in kitchen basin - seeking conical drill bit

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#1586321 5-Jul-2016 12:11

I got a nifty thing with a suction cup to guide diamond saws for drilling aquariums, perhaps one of those would be ok with a holesaw too?

Richard rich.ms

Mattmannz

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#1586345 5-Jul-2016 12:20

If you are having difficulty clamping something over/under the hole, you can try gluing a piece of timber underneath where the glue mark won't be seen. Cut a piece of timber about 20mm larger than the hole and glue it in place with a medium strength glue then perform your holesaw work. Before you get all the way through with the holesaw knock the timber out then complete the cut. Once the cut is reasonably deep you won't need the centre hole

Hatch

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#1586346 5-Jul-2016 12:22

Adamww:

Since you mentioned you have a dremel clone I would suggest shopping for a Tungsten carbide burr for it. The genuine dremel ones are pricy ~$30 but you should find cheaper ones for about $10. When you say "the dremel bits are too soft for stainless", that would probably indicate the one you tried was just a "high speed steel" or worse "Chinese HSS" that would overheat and soften quickly.

I was actually looking that up this morning. I don't mind spending $30 for a good quality bit which may have uses in the future. Have you personally used any of the cheaper ones yourself?

Hatch

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#1586350 5-Jul-2016 12:24

MikeAqua:

Drill a hole dead centre on your existing plug (use a nail punch to make a dent to start drilling in).

(I'm assuming one of those stainless plugs with a rubber rim and raised centre).

Insert the plug.

Use a holesaw with a central drill bit to drill the new hole.

Stick the drill bit into the hole in your existing plug and use this to keep the holesaw centred as you cut.

This is a hole for the tap/faucet. I don't think the plug will fit the existing hole for the old tap.

Hatch

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#1586353 5-Jul-2016 12:26

ubergeeknz:

Adamww:

Since you mentioned you have a dremel clone I would suggest shopping for a Tungsten carbide burr for it. The genuine dremel ones are pricy ~$30 but you should find cheaper ones for about $10. When you say "the dremel bits are too soft for stainless", that would probably indicate the one you tried was just a "high speed steel" or worse "Chinese HSS" that would overheat and soften quickly.

Have you ever tried this though? I have found that the burr just works itself loose, and this was on regular steel, but maybe I'm using it wrong.

So in your experience was the burr not able to grind regular steel at all? I tried a cheap bit that came with the dremel tool and it simply disintegrated whilst only barely "sanding" the edge of the hole.

Hatch

797 posts

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#1586355 5-Jul-2016 12:27

Mattmannz:

If you are having difficulty clamping something over/under the hole, you can try gluing a piece of timber underneath where the glue mark won't be seen. Cut a piece of timber about 20mm larger than the hole and glue it in place with a medium strength glue then perform your holesaw work. Before you get all the way through with the holesaw knock the timber out then complete the cut. Once the cut is reasonably deep you won't need the centre hole

Great idea, perhaps use some No More Nails. Even if it ended up being hard to remove I could drill and chisel the piece of timber afterwards.

Mattmannz

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#1586387 5-Jul-2016 12:57

Not sure if I would use no more nails as that is pretty permanent but yep you could chisel it off.

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Bung

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#1586390 5-Jul-2016 13:00

BTR:

This made mad laugh given your username is bung and we are talking about holes.

Bung: You've got the wrong hole as the actress said to the Bishop.

My username is a character out of The Wizard of Id.

Bung

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#1586396 5-Jul-2016 13:10

Hatch:

Mattmannz:

If you are having difficulty clamping something over/under the hole, you can try gluing a piece of timber underneath where the glue mark won't be seen. Cut a piece of timber about 20mm larger than the hole and glue it in place with a medium strength glue then perform your holesaw work. Before you get all the way through with the holesaw knock the timber out then complete the cut. Once the cut is reasonably deep you won't need the centre hole

Great idea, perhaps use some No More Nails. Even if it ended up being hard to remove I could drill and chisel the piece of timber afterwards.

Depending on how much real estate you have around the hole I'd consider gluing something that could stay there as a stiffener after the mixer is fitted. You may have a good quality sink that doesn't need it but the last I fitted is very thin stainless relying on various ribs etc to stop movement. The mixer spout can flex.

jpoc

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#1586441 5-Jul-2016 13:45

The correct tool for this job is a knockout punch. I have had to do exactly this job in the past and that is what I used. Works just fine.

You will get a much better finish to the hole than if you use some form of spinning cutter and there is no risk of overheating anything.

Hatch

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#1586522 5-Jul-2016 16:26

jpoc:

The correct tool for this job is a knockout punch. I have had to do exactly this job in the past and that is what I used. Works just fine.

You will get a much better finish to the hole than if you use some form of spinning cutter and there is no risk of overheating anything.

I know that a chassis punch is one tool which will do the job properly, but they are rather expensive. I have however found them for hire for $15 for a half day, but not at the diameter I need. http://www.nhhire.co.nz/equipment-item/130

Hatch

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#1586526 5-Jul-2016 16:37

$8.00 + GST hire a day in Christchurch.

http://www.smithshire.co.nz/equipment/plumbing/chassis-punch-38mm.html

Bloody Auckland.

Martynnz

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#1586559 5-Jul-2016 18:02

The other thing to try is a nibbler. I used it on thick stainless to cut straight and also a hole in the centre. Mark out the outer circle and then cut inside out!

https://www.hirepool.co.nz/nibblers-to-3-2mm

andrewNZ

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#1586565 5-Jul-2016 18:23

Where in the country are you.

If you're in Dunedin I might be able to find a punch the right size and do it for you.

Edit: never mind, Auckland

ubergeeknz

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#1586812 5-Jul-2016 21:41

Hatch:

So in your experience was the burr not able to grind regular steel at all? I tried a cheap bit that came with the dremel tool and it simply disintegrated whilst only barely "sanding" the edge of the hole.

Yep, it was completely useless against steel. Impossible to exert enough control over the dremel body. I think these are designed for things like bone and hardwood.

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