enlarging 3/4" hole to 1 1/2" in clay pot

I helped a neighbor put a 3/4" hole in the bottom of a decorative clay pot for her fish pond. She enlarged the fish pond and now needs the the hole enlarged for a greater amount of water throughput to 1 1/2". I have a 1 1/2" hole saw, but centering it over the already drilled hole is easier said than done. Suggestions? Put a thin piece of wood over the hole and go through that? Put the wood on the inside (I can adjust how far the drill bit sticks out)? I'm sure some of you have had this dilemma before. I'm sure after I've broken the pot when I get done, someone will tell me "Oh, you just.... Thanks for any ideas people.

Oops Arbor? http://www.mcfeelys.com/product/HS-0...OOPSquot-Arbor

Take your 1" hole saw and cut a hole through a piece of 2 x 4. Remove the core from the hole saw and test fit it in the 3/4" hole. (you may need two cores) You might need to sand it down some to fit. Once it fits in the 3/4" hole slip the plug onto your 1-1/2" hole saw pilot bit, put the plug in the 3/4" hole and start drilling your 1-1/2" hole.

Drill 3 more 3/4" holes to get the same area.

(0.75/2)^2 * 3.14 = .44 sq in.
(1.5/2)^2 * 3.14 = 1.76 sq in.

Better, drill 2 of them and let her try it before doing the 3rd so you don't have to ask us how to fill a hole in a clay pot. :)

Glenn that Ooop hole saw adapter looks like the cats meow for his fix and a bunch of my old mistakes.

I've got to have that Ooops adaptor for future problems because I know they'll happen. Thanks for the heads up!

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Originally Posted by Matt Meiser

Drill 3 more 3/4" holes to get the same area.

(0.75/2)^2 * 3.14 = .44 sq in.
(1.5/2)^2 * 3.14 = 1.76 sq in.

Better, drill 2 of them and let her try it before doing the 3rd so you don't have to ask us how to fill a hole in a clay pot. :)

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This was precisely my first thought.

The SLOWER you can rotate the hole saw,the less you will ruin it.Have a hand brace? I've enlarged arbor holes through grinding wheels by running a lathe at the slowest back geared speed and just using a HSS drill. Preferably not my best HSS drill,as it MIGHT get a little tapered from this operation. It does work,though,and was the older recommended way to drill a grinding wheel. Your problem sounds similar.

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Originally Posted by glenn bradley

Oops Arbor? http://www.mcfeelys.com/product/HS-0...OOPSquot-Arbor

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That is such a neat idea! What I've done in the past is fill the hole with a plug (glued) and then re-drill.

Mike

Use a RotoZip spiral saw with a ceramic tile bit.....eazy-peazy.

Take a piece of plywood bigger than the pot and drill the 1-1/2" hole in it with the hole saw. Screw or nail some guides on the plywood to keep the pot from wandering after you have centered the new hole over the old hole. You can also use carpet tape to hold it in place. Then drill the new hole using the plywood as a guide to keep the larger bit from wandering. You are controlling the position of the new hole from the outside instead of the pilot drill.

What Floyd said. That's how I always enlarge a hole.

My thoughts are similar to Floyd, but sandwich the pot between two pieces of plywood, then drill the 1 1/2" hole through all three.

If you or a neighbor has a sandblaster, they blast holes of any size and shape in clay pots in about 15 seconds.

Perry

Do you have a 3/4 hole saw? You could maybe mount the 3/4 inside the 1 1/2 and use it to center the larger? Not sure if you can find one that little. Once started, remove the smaller.
Dan