JINGLING 2.5mm 3/32" inch Diamond Small Drill Bit Hole Saw Masonry Tools for Glass Tile Stone Pack of 20Pcs

The tip of my bolt extractor snapped off when using it on one of the bolts on the underside of my lawn mower deck (the bolt head broke off), the bolt was old and rusted. Two days of penetration oil didn't do enough. So, the bolt extractor was used to get the bolt out...that was a no-go when the tip snapped off and was fully stuck in the pilot hole.These bits were purchased to see if they'd help in wearing down enough material to get the bolt extractor tip out before I drilled through the bolt and re-tapped it. The extractor being a far harder steel made using my usual drill bits a no-go in attempting without something like diamond coated hole saw bits. So, with as many as come in this pack, I figured why not? It's cheap and a useful test.I went through about 4 of these, ensuring I kept the bits cooled with a container of water (dipping the bit in ever ~5 seconds of drilling), over the course of about an hour. Gotta go slow, don't apply more than a very light pressure if any, let the hole saw do its thing by abrasing the metal slowly. Worked great, the extractor tip fell right out eventually, and I've got a bunch more of these for the next time!

Work so much better than regular diamond drill bits. They do clog up fast and I found it’s best to clean them out often.

Nice value for the money

I have only drilled 6 holes so far, but I am still using the first bit. I have drilled marble, slate and granite all with the same success. If you are drilling a deeper hole, snap off the column created by the core bit so it does not bottom out in the bit. Also, use a small wire to keep the bore clean. Sometimes you have to crush the material in the core of the bit to get it out, but just insert a small screw driver or nail - i uses a masonry nail sharpened to a point - and the bit keeps on going. Don't press hard on the tool and you will see the water get cloudy around the bit as it cuts through the material.

Para perforar vidrio son buenísimas y sobre todo el hueco de 3mm

I bought the 2mm version of these bits which seem to have a design flaw. The VERY shallow hole (perhaps 1 mm deep) at the business end of the shaft almost immediately fills with the debris of whatever you are cutting through. As soon as this happens you cannot drill any deeper. You have stop and try to dig out the debris and get back to business. Very tedious. Ultimately though, I was able to drill a very small hole through porcelain tile and that was my goal.

I've struggled with multiple types of diamond encrusted drill bits with no success, but I'm thrilled with these. I've been drilling holes in 6mm or more glass pendants all morning with no problem and much quicker than solid bits. To add to the pleasure of working with these bits, I've had no blow out on the back side. Just nice clean holes all the way through.There is an occasional noise when drilling that I think is the core moving up into the bit. Don't let that bother you.The only problem I have now is my lousy judge of the center of a thing but even that I can fix with these. I just gently push in the direction I should have gone and make a wider hole. Then I make a bail to keep piece from sliding within the wider hole.

These are terrible. Won't cut through anything unless you want to wait a month for it to make it's way through the material. Would not recommend. Would not buy again.

drilled into rock as hoped would buy again

I was easily able to drill a hole in the bottom of a glass vase. Obviously I made sure that there was lots of water for cooling. Would recommend.

Great for drilling through our beach rocks, sea glass and shells. Found these to work best so far. We use in our drill press and they last a long time. I ordered more.

JINGLING 3 mm 1/8" inch Diamond Hole Saw Core Drill Bit 's outdo what they advertised.I used the diamond bits through quartz crystals & they worked really wellI'm impressed !

Keep the bit wet and you'll be fine.Looks cheap, works great. I drilled 6 holes with 1 bit in ceramic floor tiles to see how far a bit would go