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Drilling through enamel cast iron sink

SBColeman's picture

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Yes, I know I'm not supposed to do this but I started it and now can't find a tool (bit or hole saw) sharp enough to drill out a 1.5" hole for a water filter.

I started it using a carbide 1/4" and then 1/2" concrete bit and then used a sawsall w/carbide blade to try and widen the hole. Now I'm at a lose. Any ideas or tools I should go after. I do have an enamel epoxy repair kit to handle the scratches and any chips that result. I thought there might be something in the plumbing trade but haven't found it yet.

Thanks

(post #170863, reply #6 of 7)

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Yes, I know I'm not supposed to do this but I started it and now can't find a tool (bit or hole saw) sharp enough to drill out a 1.5" hole for a water filter.

I started it using a carbide 1/4" and then 1/2" concrete bit and then used a sawsall w/carbide blade to try and widen the hole. Now I'm at a lose. Any ideas or tools I should go after. I do have an enamel epoxy repair kit to handle the scratches and any chips that result. I thought there might be something in the plumbing trade but haven't found it yet.

Thanks

(post #170863, reply #1 of 7)

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I've never tried to do this but if I had to, I'd probably get an abrasive hole saw. It might cut the enamel without too much shattering and It will cut the cast iron (if the enamel doesn't hurt it too bad.)

(post #170863, reply #2 of 7)

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SB, The abrasive hole saw it the ticket for the enamel but I think you're going to have better luck with the appropriate size High Speed steel hole saw for the cast iron. Since you've already started a hole, you'll probably have to clamp a piece of oak or some sort of hardwood to the sink, drill through it and use it as a guide for the hole saw- the pilot bit on the hole saw has nothing to guide it. Once you pierce the enamel, swap over to the HSS hole saw for the cast iron and drill away. No lubricant- Cast iron cuts fine without.

S.

(post #170863, reply #3 of 7)

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I was into Boeing's surplus store quite a few years ago, (while I was a sculpture student.), and bought a carbide 'hog' bit. I have used it for hogging out holes to any size in any material, and for gouging and forming in cast iron, cast bronze, aluminum, copper, etc. I have no doubt it would work here. It is still going strong after all these years.

I don't know the exact nomenclature for the bit. But if you saw the bit, you'd recognize it. Looks like one of those stepped drill bits, but without the gradiated steps, (thousands of teeth and the taper from the tip to the shank is smooth). I suppose it was made to be used in a grinder, (Kinda like a giant dremel tool), but it works great in my makita 3/8 corded drill.

If you cannot get one of these, you CAN get a long. tapered grinding stone to be used in the drill. It will take a while to get the hole you want, but it would be safe, (for the sink), and with patience you can get the exact size hole you need.

(post #170863, reply #4 of 7)

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Had to drill a hole in a cast iron Kohler tub a while back. I used a diamond abrasive bit and a heat dispersing gel that I can't remember the name of. If the sink is still portable you might find someone who does core drilling to finish it up. Good luck Skip

(post #170863, reply #5 of 7)

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When I needed a hole in my new cast iron sink, I called a filtered water company and arranged for their installer to come over. He used two different hole saws starting with one that appeared coated with diamond or carbide and finishing with a toothed one. The first one had a spring on it that prevented direct pressure, just a constant pressure delivered via the spring. This cut through the enamel layer and the second hole saw finished up through the cast iron. I don't remember if lubrication was used.

(post #170863, reply #7 of 7)

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I saw that plumber dude on TOH use a diamond grit holesaw to enlarge the hole for the faucet on an old cast iron sink. It worked fine and quickly. Probably cost a few bucks more than carbide though.