Tortoiseshell 51-Piece Metric Index Drill Bit Set, 1.0-6.0 mm, HSS with TiN Coating

I’ll admit that I wasn’t expecting too much in the way of quality with these drill bits; the price was very low for a full set like this. But my expectations were proved wrong. These are excellent drill bits and extremely precise. I use them mainly for musical instrument making on wooden instruments, but they seem to work just fine will aluminum and steel. Highly recommended!

Relatively precise hole diameters, and initial sharpness is satisfactory. However the tips dulled faster than expected, indicating any coating is pretty skimpy. Decent value here, but be prepared to replace bits piecemeal after a couple uses if you need to drill harder materials. These are usable bits, but not particularly high-quality or durable.

Most bits are 0.03mm under size which is good enough for me. Few bits are 0.05mm under sized. Because of the invisible embargo on metrics in the US (last country on earth with Canada not metric in every day life), I am already happy that I could purchase metric drill bits. I got a second 3.4 instead of the 3.3. The seller is sending me a 3.3 bit right away.

Everything about this kit is smack dead average. The box is a little rattily, awkward to open and the way the bits are placed is not bad but hard to see the numbers. The bits themselves are not the correct size. As others pointed out, if you're looking for precision this is not the right place. For example, my 4.0mm is actually 3.941mm (measured with a certified Mitutoyo 293-185-30 Quantumike Micrometer). Also, two of the bits I got already came with chipped tips. I'm giving this 3 stars instead of 1 since they're actually super cheap (<$2 each) and I can always measure for which one will get me close enough and then I'll just use reamers or boring tooling to get me to final dimension.

work great and cheap.I wouldn't use them for any heavy drilling but great for finishing prior to tapping.

Many pf the drill bits were unfinished/dull, and the ones that were sharp failed quickly when working with Al/steel/other-materials. Diameter measurements may be accurate, but I did not measure. This is one of those stux-net style products made to waste time and harm production. There is nothing more damaging than the IUU; if one gets in they will destroy your entire culture.

OK, you'd expect that of a machine drill bit, but the last bits I got from Amazon would not cut brass, so I'm very excited that these do.

I use these for sizing small holes in 3-D printed. They work very well.