TARGET Super Premium Dri Bit -- Depth 10", Size 4 Inches
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br /I used this bit to cut three holes through a brick block house. It was the right size for a dryer vent and a small exhaust fan pipe. The other hole was to provide outside air for a gas furnace - the 4" bit cuts the perfect sized hole for 3" PVC fittings.
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br /To use this bit with a drill, the Felker 420106 Jacobs Chuck Adapter is needed.
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br /My 18 volt Bosch Brute drill was not sufficiently powerful for this bit. Instead, I used a DeWalt DW235G Heavy-Duty 7.8 Amp 1/2-Inch Drill with the side-handle mounted. Whatever tool you use, make SURE you use that tool's optional handle - otherwise, when the bit binds, which it will, you could get hurt.
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br /Pros:
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br /-- Even though the masonry wall was 12.5" thick, the entire cut was made from the outside of the house. This was possible because the drill's chuck was inside the hole as the bit was breaking through the far side.
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br /-- The hole was very smooth -- infinitely better than would be possible with any other tool. From the basement side, where the bit finished cutting through the cinder block, there was no breakage at the hole entrance. Just a very smooth 4" hole, as though the block was made that way.
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br /-- The hole was a smidgen too small for a 4" galvanized steel pipe, so on one hole, I used the bit to increase the entire length of the hole, by honing off additional material.
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br /-- The bit cuts fairly quickly through brick, but goes like the dickens through cinder block. Obviously, for any hole more than 10" deep, the bit needs to be emptied of material as you go along. Wear a respirator when using this bit, as there will be lots of brick dust.
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br /Cons:
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br /-- No instructions come with the bit. I called TargetBlue dot Com technical support, and asked the recommended cutting speed through brick block. They said 1400 RPM +/- 200 rpms. This was important because I have right-angle grinders with 5/8 - 11 threaded hubs, but those tools turn at much higher speeds. TargetBlue also sells self-guiding dri-bits which use a small center bit to guide the core bit. Since this model is not self-centering, I was worried that the bit would "wander" so much and so fast, it would be dangerous -- at least until it started the cut. To prevent this, I cut a 4" hole into a 12" x 12" scrap of 1/2" plywood, then affixed the plywood to the house with masonry connectors, with the hole positioned properly. I slipped the dri-bit into the hole in the plywood and the bit didn't wander at all. Once the hole was about an inch deep, I removed the plywood. Check the bit with a level and/or square before you go too far. Minor alignment adjustments are possible at the beginning, but once you are several inches in, it's more difficult to straighten the bit.
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br /-- One of the bit's teeth snapped off during the honing step on the first hole I cut. At the point where the teeth are laser welded onto the tube, there are many tiny air pockets, which appears to be the result of incomplete welding. I'm not a welding expert, but it would seem that the welds should be stronger. The second two holes didn't need to be honed, and no teeth broke off.
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br /Summary:
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br /Without a core bit of some type, your only options are to pound or chip-away material to make a hole in a masonry wall. E.g., an air hammer with a chisel blade works, but the resulting hole is anything but smooth and neat and the surrounding bricks could be loosened with all the hammering. Using this bit will give you a smooth, nearly perfectly formed hole.
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br /I rated it at 3 stars because a bit's tooth broke off on the first hole.