Countersink Drill Bit (7 PCS), Drill Bit Set with One Hex Key, High-Speed Steel Drill Adjustable Carpentry Reamer Plated for Wood DIY (3-10mm)

Sorry to be giving these a bad review, but my experience was none too good. I was drilling pilot holes into 3/8" plywood in order to attach the sheet to 2x3's. First off, the countersink had a hard time boring the plywood and sometimes slipped on the bit. Finally the bit itself broke after 8 holes. I can replace the bit with one of my own which is why I bought this set. I'm no novice when it comes to pilot holes so for once I can't blame a tool's failure on my own ineptitude.Edit: I should give the seller's customer service credit for quick action. They have offered a replacement or refund.

Used the smallest two bits first. The metal collar spun so I had to tighten it, the Allen set screw wasn’t squared off enough for the Allen key provided. Or any Allen key to be honest. Not sure what the issue was but it was like they were “stripped”. After carefully tightening it, still don’t know how I did it, I began to drill the hole. About halfway down the 5-6 hole, the bit it snapped. Drilling straight, soft enough wood etc. I took out the next size up and same thing. Disappointing to say the least. The next size up was too big so I ended up using the “nub” because I was in a bind. I ended up grabbing a bit from a local hardware store (for the price of this whole set for one bit) and it worked fine for the remaining 15 holes. So it wasn’t the wood, the drill, me or anything. I thought these would be a great set as they se hefty enough both in the picture and in person.

This product comes in a small cardboard container lined with durable foam as shown. Each counterbore bit comes with the appropriate size boring bit and an allen wrench to tighten the set screws that hold the boring bits in place.Check for tightness before using as it is much easier to adjust and tighten that wat. The screw on the #8 bit held onto the wrench for dear life and it took pliars to remove it.This set is unmarked, so you will need a handy gauge to figure out the size.It’s also hard to tell how deep the counterbore hole is. This is easily solved by flagging the bit with tape, but i like the “built in” markings on the more expensive bits.When drilling, you need to apply more downward pressure than you might expect. The picture of drilled holes shows how ‘rough ‘ edges are on left and how the #8 broke off in fairly soft treated pine 5/4 deck board.I gave it two stars — one for rapid delivery and one for decent packaging. Unfortunately, my first use was after the return window closed.

This product is cheap for a reason. Every single countersink is the exact same size. The skinniest drill bit has a mondo countersink. I need one the size of a normal screw head. Not one that’s huge. The return policy is non existent which I wish I knew ahead of time. I will probably never use these. Sad. I’m going to have to buy locally because you can never tell what you’re going to get from 3rd party Amazon sellers.

PROS:1. You can slide the countersink attachment up and down the solid part of the drill bit shaft to set drilling depth to a degree;2. You can replace the drill bits with higher quality drill bits.. but you might need to.CONS:1. Quality is terrible - there are filing marks on the countersink attachment slots;2. The drill bits don't center in the countersink attachment holes when held down by the grub screws;3. The drill bits seem good for soft wood only, but are replaceable.4. The item is non-returnableBuy DEWALT instead. You probably dont need 7 different sizes and DEWALT has hex heads for driver use:https://www.amazon.com/gp/product/B0000225OU

My bots came in and I immediately used two of them on a project. The first one broke almost immediately. The second bit worked but the countersink portion was not straight. No matter how many times I tried to adjust the set screw it was always cockeyed. Disappointed to say the least

I was building a triple bunk bed for my kids with 2x6, 2x4, and 1x5, and I was using these to drill holes for the screws, and two of bits broke, and the countersink section isn't very sharp burning the wood at times. At the beginning, it worked pretty awesome, but it appears these bits get dulled pretty fast, which is probably the reason two of them broke and burned the wood.

The two smallest bits broke under slight pressure. The countersink cutters are not sharp at all and it takes considerable effort to make a countersink. Monkey Fart.