What kind of bit to use to drill through quartz?
March 29, 2021 12:14 PM   Subscribe

One of these lasted about a minute. Carbide tip SDS bits last about has long, either with drill or hammer/drill. Yes I'm using water.
posted by falsedmitri to Home & Garden (7 answers total)
 
That bit in the link should be fine. The trick is relatively low pressure + high RPM + coolant flow. No hammering. Let the bit work for a bit and then release pressure and clear out all slurry. Be patient. You can make a little dam with playdoh so it's completely covered with coolant.
posted by Dmenet at 12:28 PM on March 29 [5 favorites]


I wouldn't use a hammer-drill (at least not in hammer drill mode)-- you want to abrade the surface rather then chip through it.

You're on the right track with the first link-- I think you just need to get a better one-- something more like: DAMO 1/2 inch Dry Wet Diamond Core Drill Bit for Concrete Granite Marble Hole Saw. That fits on a grinder spindle-- but you can get a adapter for a drill (slower hole making though that way)
posted by Static Vagabond at 12:31 PM on March 29 [1 favorite]


Agree with others, but I'd get a cheap Harbor Freight angle grinder rather than using a drill. (Or a decent angle grinder, if you plan to do this more than once.) The extra RPMs will make things less tedious.

Definitely do not hammer/drill or even press hard, it's not like drilling masonry. Don't think of it as drilling, you're really grinding a hole. Lots of coolant flow. Bigger diamond holesaws will actually have cuts in the side to let coolant in, but it looks like the 1/2" ones tend not to. So you'll need to pull it up out of the hole frequently, clear the slurry/debris out of the work, then resume.

Diamond bits shouldn't get hot in operation; if you pull the bit out of the hole and touch it, and it's more than warm to the touch, you are not using enough coolant / you're using too much pressure.
posted by Kadin2048 at 2:24 PM on March 29 [3 favorites]


Diamonds should do it, but no hammering/impact tool. Gentle pressure and lots of water to cool and clear the swarf/grit. Let the diamonds do the work, not your muscle. Too much pressure dislodges the diamonds from the cutter. It also creates too much heat, which can also dislodge the diamonds. If possible, use some kind of fixture or vise or drill press to keep the workpiece as immobile as possible.
posted by 2N2222 at 3:20 PM on March 29 [1 favorite]


I assume you're drilling a quartz countertop rather than native or cast quartz, and since the countertops are around 7% polymer binder, if you let the bit get hot it could melt or burn the binder, which could then coat the bits and stop them from cutting.
posted by jamjam at 5:08 PM on March 29 [2 favorites]


Response by poster: @several mefites:
Oops I was doing low speed / high pressure. I will set the drill press to high gear.

@jamjam:
I am not drilling countertop. Actual rocks.
posted by falsedmitri at 8:36 PM on March 29


Based on some very slight experience with these sorts of bits: 1. reduce cutting pressure a lot and increase speed somewhat and 2. the quality of the bit seems to matter hugely. The diamonds are held in a sintered metal matrix: if the matrix does a good job of holding the abrasive rather than failing and letting it go as grit, the bit will cut faster and last longer. I have an old Starrett hole saw that's outlasted every other cheap home-improvement-store no-name I've had.
posted by introp at 11:12 AM on March 30 [1 favorite]


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