Bosch HDG4 4 in. Diamond Hole Saw

Bought to drill a 1/2" hole in a polished granite kitchen countertop to install a faucet for an under sink water filter. Diamond grit edge cut smooth and steady, and it removed a solid plug of granite that was just the right size. The bit showed no appreciable wear when done, and should perform well for a while. My basic DeWalt cordless drill/driver managed the job just fine. Important to follow instruction diagram to start bit at an angle to create a crescent shaped cut on the polished surface to guide the bit before tilting it up to vertical or else it may wander. Also good to have a water bottle handy to wet the bit and the cut as you proceed. This serves to keep the bit cool and to stop flyaway dust. I highly recommend this product and I would buy it again.

I was very pleased at the performance of the bit will drilling through tile that would have been impossible to replace due to its size. Just start the hole on a 45 degree angle then gradually go perpendicular to the surface. Use patience and a slow speed with plenty of water spray to flush and cool the bit. Don't worry about the core plugging it will easily push clean with a small nail since there is a slot in the side of the bit. Clean often while drilling. 4 holes showed no change in performance. Buy a brand you can trust.

It works very well

Worked great for my dryer vent through brick. -1 star only for having to use their proprietary arbor/mandrel (I read you can remove it with a special tool but I couldn't get it off)

I’m going to be honest this high density porcelain tile that I picked has been rough for this project. It’s been very finicky if you don’t cut it perfectly and tends to chip. The aggressive nature of the saw had me worried but Amazon has it for half the price anywhere else so I decided to take a chance. If you look at the close-up picture, I have to say I am more than impressed and if you follow the directions (low speed and water) there is virtually zero chipping. AMAZING! Now for the four-star ease-of-use. The center guide bit you need to order separately has some problems. Again this has nothing to do with the Saw. The center guide has at least an eighth of an inch either way tolerance and bottoms out on the top of the tile buy just under 1/16 of an inch and makes it nearly impossible to go all the way through straight without rocking the saw that can cause additional chipping. Now the bottoming out of the center piece I have not resolved but I found with the accuracy I needed for this project I just used a piece of Wedi board, used the saw to cut a hole in it and then clamped it to the tile to make a perfect guide for the saw. Incidentally this also helps with water retention and helps cool the blade for a faster cut.

This bit did what we needed it to do. We needed to drill through a quartz counter to install the faucet for an under-counter water filter. We only needed to drill one hole so I can't say whether it would hold up for multiple holes, but that one hole went through quickly and easily. I used a corded hammer drill but didn't put too much pressure on the drill so as not to stress the bit of the counter. Another reviewer named "Al" had good suggestions on how to make the hole. Look for that review for advice on how to use it.

We used this for a non typical situation... so our results may vary from what you will experience. We needed a 1.5" hole to install our Aquor hose hydrant. We have 4" thick limestone slab skirting around our foundation, with terracotta structural block behind it in this particular section. The previous hole for a frost proof spigot was 1". Knowing that 100yr old terracotta block and limestone can be sensitive we needed to minimize blowout, so went with a brand name vs one of the random ones listed here. The price was cheaper than a coring bit, so figured why not. (* If you need to install an Aquor* The sizing is accurate on this, so that's a positive! It does fit so that you have just enough meat left for pre-drilling holes for screws, if your in the same position as us trying to fit the fat portions of the circle faced Aquor into Masonry. Hopefully you have a newer construction home that's just a brick veneer with regular concrete and plywood framing. ) [Considering a bulk of the stone was already removed, it seemed reasonable this should work effortlessly.] Despite water and keeping the diamond teeth clean by continually removing build up, pausing to allow it to cool down... it struggled. This with a Bosch Brute Drill and a Dewalt 20v XR. It started great, the diamonds seemed to loose effectiveness quickly, while in the limestone. Once it hit terracotta it was done. So longevity for us was short lived. Value for money in our particular situation, I would say no. One thing to note, it kept getting unscrewed from the arbor, this seemed odd as to remove it from the quick connect base it came with, I had to use a vise and small pipe wrench. (Both in such a mannerism to prevent tweaking it.) So if using in a place that if it untwist, you could loose it, continually check for tightness if not using the quick connect fitting. [ I ordered a 12" Bosch arbor with the SDS+ end to use with our Bulldog, however the threading spacing was different, correct size just a different thread pattern. ***We used a Master Force #3 arbor with their extender so this could have been part of the problem***. It didn't fit the Spyder or Dewalt Arbors we already had.] I ended up switching to a 1.25" Lennox diamond saw to finish, It went through effortlessly, with the same arbor and extender. (I should have just bought one specifically for coring, lesson learned. If you have reinforced bomb proof/ bridge grade concrete basement walls... 100% just get a coring hole saw. We have two others to install that go through limestone and extra strong concrete with #11 & #14 rebar... we won't be using this hole saw. 😂) If you're using this for thin material you should be fine. I do not recommend using this on porcelain tiles though! Get a continuous diamond coated edge vs teeth.

Works great. I had bought cheaper cutters for drilling ceramic tile. They did not work well. The Bosch did the job. It was worth the extra money

Para mármol, tiene su truco , aprendiendo lo ya es más fácil , se desgasta rápido

Had I read through all 437 reviews I’m sure I would have eventually found an answer to the questions I had about this tool, but somewhere around review 92 I grew bored and threw caution to the wind and ordered the tool anyway. My aim was to run this 4” diamond tipped hole saw bit on a grinder, as I do with a 2” bit. The 2” holes are for venting and the 4” for light plates and the material is 1” thick Hardie. 1” or thinner. I’d already learned the hard way that the 2” bits mandrel thread wasn’t compatible with that of my grinder, and remedied that with an adaptor from Milwaukee (link at bottom), but would it work with the 4” as well? Much to my delight I found that the 4” shares the same thread pattern as the 2” once you’ve removed the mandrel housing adaptor (I don’t know what the part is actually named so that’s what I’m calling it) that comes screwed into the hole saw. Understandably, these hole saws are meant to be run on mandrels in drills turning at appropriate speeds, not on the business end of a grinder spinning at slightly faster speeds, and so this 4” is shipped with an adapter screwed into it so it’s compatible with the mandrel. But again, to my delight, that adapter spins right out, and then hole saw spins onto the Milwaukee Grinder Adapter which is spun onto the grinder. So long as everything keeps turning to the right, it should stay that way. Though I do offer a warning (it can get a little western cutting 4” holes through 1” Hardie at questionable rpms) I also leave a strong recommendation for this set up. Until they come up with a better way, this is pretty good. The bit lasts longer than any other. It’s super fast. The plugs either fly right out at dangerous speeds or, at most I have to tap the bit a couple of times to shake it out. And it’s easy on the grinder as the bits doing all of the work. So I really hope someone gets something from this, should they have the patience and time to sift through the 438 reviews. That adapter can be found here... Milwaukee 49-56-7105 Milwaukee Angle Grinder Adapter, Large https://www.amazon.ca/dp/B00KZHGE12/ref=cm_sw_r_cp_api_i_yG8nEb5GSG71M

AMAZING!! I'm so happy with the product. It cut through 1.5" natural stone. I had someone with a spray bottle adding water every 3 seconds. Made 8 holes with medium pressure, med-fast speed. Need to by mandrel so you dont spin out. First drill a 5/32" hole with different bit then stick mandrel in with hole saw. Start low then pick up speed. Once the insition is made with hole saw pop out pilot bit and finish hole with just saw.

Excelente broca, cara pero sirve muy bien

Perforó la cerámica perfectamente