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For drilling soft (terra cotta) to semi-hard (vitrified clay/ceramic) material, the 3-point/spear point bits are far superior to (and faster than) masonry bits. If the material I'm drilling is relatively soft, like terra cotta or glazed clay, I generally use water as the coolant. I either submerge the pot I'm drilling in a larger plastic tub so the drilling surface is just beneath the water (no need to stop drilling periodically, the object/tool interface won't heat up using this method); or alternately, I'll fill a contact lens solution bottle with water and apply a slow, continuous stream of water to the cutting tool interface area as I'm drilling. For harder material, a 50/50 mix of antifreeze and water, or turpentine, are among the best coolants likely to be handy, and will add considerable life to your cutting tool.
For extremely hard and/or thick material, I'll use a diamond impregnated core drill with water as the lubricant - for glass, granite, highly vitrified pottery. Though I have a drill press at home and several at work, we/I usually prefer a battery operated 18V drill such as that made by Milwaukee, DeWalt ... for drilling. Applying lots of pressure isn't necessary, as you should be letting the tool do the work. Also make sure, if your drill has one, that the hammer function is out of play as it would increase the odds of fracture significantly.
BTW - there is no advantage in having more than 1 drain hole insofar as the end result is concerned. Good 'drainage' is a function of soil choice, not the number or size of drain holes. 1 unclogged drain hole at the lowest part of the pot is as effective as 100. The only advantage in having more drain holes would be if we got some degree of satisfaction from seeing the pot drain in 30 seconds instead of 45; but the plant won't care.
Thanks for the information!! I copied to my favorites so I can save it for other applications.
See, This is why I subscribe to Dave's Garden. You never know what kind of information you