Customer Reviews for Drill America 1/8 in. x 6 in. Cobalt Aircraft Extension Drill Bit

Use this to drill a 40 degree angle through a 4x4. Because the cutting edge is not all the way up, I had to pull the bit out so it could clear the cuttings.

These bits maybe cobalt, but they are pretty crude. The flutes are poorly cut. The bit tip was poorly sharpened and even damaged. The butt end of the bit is hand ground/sanded. Even the cobalt on the bit is hand written and of course, there is no country of manufacture, which I think is illegal. There is certainly no American in these Drill America bits. Photos compare Drill America bit to a real American made Co drill bit.

This is a bit that for all kind to steel products and hard metals like stainless steel or nickel alloys. The cobalt gold oxide helps improve the performance when cutting harder metals. It has a 135-degree split point is self-centering. When I use it on stainless steel it cut very well and it went through the stainless steel will very little effort. Great bit!

I have used hundreds of drill bits over the years. The first thing I noticed with this bit is it doesn’t walk off on the metal you are cutting which is a huge plus. I used it to cut through a metal gate to install small diameter fencing onto the gate with u bolts. The performance is very good. The heat resistant cobalt works far superior to other drill bits we have used. Plus the extra length comes in handy! So far we are very happy with this drill bit!

This is a high-quality brand name in cobalt alloy twist drills, designed to cut hard metals and to last longer and withstand more heat buildup in use than conventional carbon steel bits. In checking it out, I found that minimal research on the internet among user reports confirms that it can be found rated as among the top five brands for performance and long lasting durability. Selecting the right twist drill for the job at hand is everything, as there is no such thing as a general-purpose twist drill that will do a good job and hold-up in all materials. This cobalt aircraft extension drill bit has a self-centering 135-degree attack angle, and a six-inch length, so it can reach into recesses and cut deeper bores than a traditional drill. The significance of a self-centering cutting tip is that it reduces the annoying tendency of many drills to skip off center when you are attempting to start a hole in especially hard or curved metal surfaces, that can make it difficult to achieve a clean hole and a surface that is not damaged by false starts. Aircraft drills are commonly available in both six inch and twelve-inch lengths. The longer length can be difficult to handle, especially in smaller drill diameters, because they can bend under relatively light drilling pressure, that can result in producing holes that are not true and straight. They are also more prone to false starts due to skating across the surface before getting a bite into the metal. Friction between the drill bit and the work piece, and the high working temperatures it can produce, is the enemy of your expensive tools, including cobalt. When working with hard steel and some alloys, always keep the work surface and the drill bit well lubricated with suitable cutting oil, and keep adding it as you work to keep it cool and well lubricated. Household lubricants like 3 in 1 or sewing machine oil also work well. This will pay big dividends in longer service life for your drill bits, prevent heat discoloration in the workpiece, and help keep the metal filings contained right on the drilling surface, instead of flying all over the floor and becoming a hazard. Cutting oils will also start to smoke when the heat builds up, telling you it is time to rest the drill bit, and add more oil before continuing the bore. The use of a drill press vice, an inexpensive accessory, will also produce better results, and will offer a lot of protection from serious personal injury while working with high speed drills and smaller metal parts that might get away from you if the drill bit binds and the piece starts to spin.

The longer length is certainly a big help to me. When restoring old cars getting the drill into tight spaces is sometimes impossible so a longer bit like this can be a lifesaver. Drilling out spot welds and broken off bolts are very challenging because they are rarely in open areas. While this bit is well made and seems durable, using a drilling lube is essential if you are dealing with a deeper penetration when heat buildup can kill even the best bit quickly.

Drilling holes into metal requires the right tool. This bit is the perfect tool to drill 7/32" holes. The 6 inch length allows for you to reach into tight and small spaces and or drill through thick material. The point is 135 degrees and the cutting flights extend upward for 2 inches. Makes quick work of the job. I would suggest this bit is better suited for a drill press rather than a handheld drill due to its longer than normal length. Be sure to use proper cutting oils to increase the life of the bit. Overall, performs as intended.

This is a good drill bit, and sharp as any I’ve used. I don’t normally need a bit this long, but I was having difficulty drilling a hole into a wall for a door hinge using a conventional shorter bit. The shorter bit would not allow me to drill straight into the hole because the housing of my cordless drill would not clear the hinge hardware (see picture). Using a longer drill bit like this extension bit was the perfect solution, allowing me to extend the drill bit past the door hardware so that I could approach the hole at a 90-degree angle, and straight into the desired hole position. I seldom face this type of challenge drilling holes, and sometimes I make a mess of the hole or the hardware by using short length drill bits. This longer bit solves the problem nicely and is reasonably priced. I would recommend it to a friend for similar circumstances.

This is a very well-built drill. The flutes are consistent, the tip grinding is spot-on, and it seems to hold up very well, in my limited testing. It stood up to a significant amount of bending without problem (I deliberately drilled off-center from a previous hole), and had almost no tendency to walk, even though it is longer than a standard drill.

You may wonder what is a Cobalt drill bit good for? Cobalt drill bits are constructed and designed to be able to drill particularly hard exteriors such as cast irons, titanium or treated stainless steels. Cobalt drill bits are made from steel and cobalt. It is made to withstand high speeds and be long lasting. One feature this drill bit has is a 135-degree split point tip to prevent "walking" when drilling a hole. This 6-inch long 3/8-inch Cobalt Aircraft Extension Drill Bit is manufactured to National Aerospace Standard 907. When using this drill as with any high-speed tool, using protective goggles is a good practice to follow, and don't rush, take your time. When I used this drill bit on a home project, it worked very well for me.