Carbide Burr Set 8pcs JESTUOUS 1/4 Inch Shank Diameter Double Cut Rotary Files Metal Grinding Polishing Carving Tool Drill Bits for Die Grinder Kits

I saw this product on Project Farm on Youtube. This is what you want if you need to enbiggen (TM) a hole or make a slot, etc in carbon steel. I paired these with a corded die grinder from Harbor Freight and they work great. Great value!

I would definitely buy again.

So far the one bit I’ve used has worked great!

Got a chance to use a couple of these burrs to grind into a very hard metal. They did their job, did not break. It's nice to have them in a convenient, strong case. Just open it up and see all the shapes available. Use one. Snap it back in when done.I rate high for Durability and Longevity based on when I see in the quality. It is hard to evaluate since I only just received them and used them a couple of times.

These are very tough bits but not capable of grinding through hardened steel. I breach old payphones as a hobby, which have two locks (top for phone, bottom lock for coin box). The bottom lock is super hardened steel and these did nothing to it. However they shredded the top lock and had no signs of wear at all. The one pic on here of the worn bit looks like it was somehow spun in reverse (must not have used a real die grinder for the bit) or maybe didn’t use any cutting lube. Even on the hardened steel despite not making any considerable dents, the bits still didn’t get damaged or worn.It would have taken 12+ hours of grinding away at the hardened steel with these and still not sure they would be able to do it. Not any fault of the bits. It’s more a testament to those dang locks! Lol. Hardness matters. Perhaps diamond tipped ones are what I’m looking for.

Great bits. It took me destroying one to figure out the truck with these. I got these to clean up welds on inside corners of a project I'm working on. 1. Make sure you wear goggles AND a face mask. This is not grinding it is cutting chips off and will fling them at you. 2. Don't push hard on the item you are cutting, let the rpm of the grinder do the work.I pushed too hard and the bit grabbed and slammed into a side which created chatter and chipped my first bit. Once I figured this out my next bit worked 20x ties as long to finish the entire project and is still sharp.I used an electric die grinder with an rpm of 22,000.

I’ve ground metal with one of the bits maybe 30-40 times or so and you can’t tell. They weren’t big grinding projects. Just modifying a screw hole slightly. Still. You can’t tell. No broken pieces. No wear. It looks like it’s brand new and seems just as sharp as the others. I’m impressed and I would definitely recommend them. I have another 1/8 inch set that didn’t hold up to this project. I bent the 1/8 inch bit on my first or second hole.

A very warped exhaust manifold. Used one to fix the issues that prevented it from mounting to the head. It would have worked if I could have found a machine shop to resurface the flange faces. Gentle pressure only, let the bit do the work. Used the same one all over the manifold and it felt as sharp as when I started. I think it's a good investment.