Cobalt Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16"-1/4"

I bought a 10 pack because where I needed to use them, there was no store to buy replacements if it turned out these were junk. In the end, these (this) bit was as pleasant surprise. I drilled 30 holes in a steel I-beam with only needing a single bit and it still drills effectively without needing excessive force. The holes were drilled fast and easily with clean breakout on the backside. The drill bit cutting edge was does show some damage (see closeup image) after the 30 holes but it still drills effectively. I have no doubts the bit would drill another 10 holes on the same bit. I am surprised there is rust on the cutting edge since the HSS and cobalt is pretty rust resistant… I wouldn’t expect rust after sitting just a single day. The hardness of the bit must vary from the tip (very hard) to the shank end (soft) since there is a lot of damage where the bit slipped in the drill jaws a couple times (see close-up). Whatever the hardness range is, I’m happy with the combination of hardness and ductility and the overall drilling results. The bits come in a nice plastic case that can expand in length so it will hold a variety of bits including longer bits. The case opens easily to grab a replacement (I didn't need to) and closes tightly enough to not worry about spilling any. The case is right sized and not too big for the typical handful of bits needed. Overall, I'm very happy with these bits.

Good drill bits. They cut through metal (stainless steal sheet metal) with no problem. Good quality bits and good value for the price. The plastic case is a bit flimsy though.

I use the MACXCOIP cobalt left hand drills to remove broken bolts, studs, and fasteners. They’re very hard so they are subject to breaking. Don’t use them too agressively or with a very high speed on metal. They seem to be good quality and very sharp. These are special purpose application only and should last.me for many years. The set came in a plastic index case to keep the jobber-length bits together and easy storage. Good value.

Very impressive on its functionality. I purchased before Milwaukee and Dwall drills and they did not performed correctly, as a matter of fact, they got broke and it took kind of long to perform the drilling. With this MACKCPIP cobal drill bit set, i drilled like 5 holes with out any issue. Except for the smaller drill bit got broke, but the other one i used worked more then great!!!

Seem to be very good, solid case, great price

impressions following first, succesful, use. - bits are sharp and straight. - bits are capable of cutting deep into snapped stainless bolts without observable wear. tips: - the metal set case is tightly clipped together when closed and hard to open. instead of force, i've used a small pry tool. - drilling metal: i've started small, slow, then gradually ramped up speed and size - careful throughout. - reminder to drill "backwards" with left-hand bits. in the photo: the two bits that i've used to extract the snapped bolt, also shown.

Good set of bits

They were alright. Great for the first little bit(granted I was drilling a hardened steel head bolt that was work hardened) they fell a bit short faster than I'd have hoped but again. I was drilling hardned steel. I should have been using m42s these were just a circumstance of time. The case was handy. Over all quality was great for the price paid. The durability was pretty decent. Multiple times a bit would snap these held their own against multiple binds. Walking was minimal.they could have been longer but shortness gives it more room before they snap. All in all decent bits. Would buy again if needed for small basic drilling. Or I guess I'll just sharpen the ones I have :D

For so long I went with just whatever came with the drill. These bits are so hard, and with a little bit of oil cuts super well and stays sharp. Left hand is extra handy to drill out broken/welded in screws. Love them. Would bring them to bed if I were allowed.

Bastante satisfecho con la duración, es similar a las brocas Milwaukee titanio pero a un precio menor para ser de cobalto esperaba que duraran un poco más pero aun así muy satisfecho

No era lo que esperaba muy caras y son de medida muy pequeñas, no llegan ni alos 10mm. Yo buscaba de 8mm. sta 14mm. Pero la descripción está muy confusa

Nothing

I purchased this particular set because I needed a #30 wire gauge drill bit for a project that used 1/8" rivets . The only other option for a SINGLE bit on Amazon was stuck in "neverland" and other sites wanted $30USD for a single bit which was not reasonable. So I found this set for a good price rather than buying them singly. I am significantly impressed with the quality and strength of these bits on 550 stainless and lubricant... Though my unsteady hand meant some failed starts and controlled rpms on my hand drill. (These are probably better on a drill press). Starting the hole was easy enough as was finishing through the mixed materials and the bit did not overheat or wear. I cant say about Cast Iron or Titanium though but your mileage may vary. These would go through pretty much anything else easily as long as you had the right lubrication and Pressure/RPM control. ALL small bits (and these are all smaller than 1/4 of an inch) will break easily so just be mindful of that and go slow and steady without overt amounts of force. The bits are all neatly organized in its index and a small pull tab brings them out as well. Each bit is labelled as is its index for easy use. My only complaint (and I took a star off for this) is that the front label is upside down with no indication or sticker as to which side goes up. Otherwise I had to open my bit box on its side so they didn't all spill out on my table (thanks to reading reviews). I think these are factory rejects because of the label as the bits work just fine and are probably more expensive if the label were to be placed correctly. Otherwise I'm happy with keeping this set for what I will use them for. Though "Wire guide number" bits will not be used too often for me, this set will be very useful in the future.