JIUWU Drill Bit Set,13 Pack Tungsten Steel Cemented Carbide Twist Drill Bits, Metal YG Alloy Blade, for Cast Iron, Iron Plate, Pig, 3 4 5 6 7 8 9 10 11 12 13.5 14 15 mm

These bits are great for hardened steel. It will cut through leaf spring steel, axle steel, stainless steel and just about anything. The down side is that they are carbide, so they break easy if you aren't really careful and easy with them. They have carbide inserts, which are non reusable once broken. In other words, they can't just be resharpened and put back to work.

I had looked at the reviews for these drill bits and what made me buy it was someone had mentioned that they had drilled through a rail road anvil no problem with these bits and had pictures to go with it. I was pretty skeptical about buying these, not a lot of positive reviews but somehow a descent rating. I had a leak in my truck's exhaust (1997 Ford F150 4.6 liter) right under my drivers seat and it was pretty noisy. The break wasn't part of the piping of the exhaust but a flange coming directly from the engine (The driver's side manifold, about a foot or 2 away from the actual engine) that had normally 2 posts coming from it in which the pipping clamped on to, one was missing, the other was solid. So when I drove it around and hit bumps it would spread open time to time, it gets loud. A shop said they wanted to replace the manifold (A lot of work, potentially days worth if posts break). I opted into buying these bits and just drilling a hole through the flange and slap a bolt in that mofo. Worked like a charm, quiet as can be. I didn't even drill a pilot hole. The drill bit that matched my bolt just sliced through that almost 1 inch steel flange no problem. My advice though (I used a basic plain jane drill, a black and decker from Walmart costing nearly nothing) wear long sleeves and eye wear. The shavings get everywhere on your arms etc. and stays for days. Otherwise, great drill set. It slayed what I wanted it to do and I only used one of the many many bits. This one time buy was well worth the fix versus shop costs. Added pics with.

Purchased these to drill through grade 5/8 broken seat bolts in my trans am. With the set I was able to drill about 1.5 inches worth of material. In the end I dulled the bits I used (even with cutting fluid). I only used the four smaller sized bits. In the end I accomplished what I wanted and saved myself some cost verse the alternative. I used a hammer drill for this application. So in the end I burned the cost of the set to drill out 3 broken bolts. I would recommend this set for a limited/specific job rather than a tool box keep set. Thanks

These things saved me. A threaded stud post was seized in my turbo, and the stud remover snapped the stud off at the base of the flange.Using these carbide tipped bits and a cheap off-brand cordless drill, I drilled through the 1” of hardened steel in the course of about 15 minutes. Without these, I would not have been able to fix my exhaust leak and it would have set me back over $1000 in labor to remove the turbo, machine out the stud, and reinstall.It is vitally important to take a slow and steady approach when using these. Use a punch to center the bit, then start with a relatively small bit. Use plenty of lubricant (I used leftover automatic transmission fluid ATF) and take breaks to let the bits cool off. Re oil, then go at it again. Started with 3mm, then went to 5mm, 6mm (this one I tried to rush and snapped the bit), then to 7mm, 8mm, 9mm, then 10mm.I will always keep these things on hand now. I don’t often do metal work, but they are really good to have in a pinch.

I received these just today and I immediately started using them on a cable railing project. As I drilled some of the posts, I noticed that some of the hardware did not fit in the holes I drilled. So I used 2 different digital micrometers to test them and here are the results: 10MM = 8.4MM, 12MM = 10.7MM, and the 13.5 and 14MM bits are both identical at 12.7MM! Needless to say, I had to re-do many holes and at least 4 hours of work! They cut well, the price is excellent, but C'mon Folks, these are machine drilling products you're selling here. The last thing I expected was to find that a third of these "drill bits" were the wrong size! Since I used some of them already I will keep them and not bother with a return. Unless you enjoy re-doing your work, and re-labeling drill bits, I advice that you not buy these.

Went through alot of name brand drill bits. This did better than all of them on stainless steal. Saved me a ton of time. Cannot beat it for the price. These are low speed bits. They will burn up like most if you drill fast. Take your time.

Thdy are good but not the high quality that the seller claims

I purchased these drill bits because I needed to drill out broken exhaust manifold bolts in a cylinder head. They cut through the bolts pretty well. I went slow with the drill speed and used ample amounts of cutting fluid. It took about 20 minutes or so per bolt. They appear to drill better and quicker than my colbalt drill bits. I realized that I could use a drill bit closer in size to the hole to start drilling. Doing that ment I only need to use two or three drill bit sizes, instead of progressively moving up in size from smallest to biggest Overall they worked very well for me, I think they were a good buy.