5mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 2pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO

Why did you pick this product vs others?:I like the durability of cobalt bits for hardened steelDurability:When used with oil, these will last several low speed drilling projectsValue for money:Cheaper than big box hardware storesSize:I use alot of odd metric sizes and these always offer the size of hole i need to createI go through a ton of drill bits and I have found that the cobalt bits found on Amazon are the best value for my money. If you use a tapping oil these will cut cleanly and leave a nice hole fairly quickly. I use these drill bits around 500 rpm or less for the best results.

I used the 8mm bit to drill 2 holes into the aluminum pole of a patio umbrella. Now the weighted base's hand-screws that secure the umbrella pole to the weighted base can go directly into the umbrella pole for a MUCH MORE secure fit, rather than just a friction hold. Now, the only way the umbrella pole will come out of the weighted base is if both hand-screws shear off at the same time. Which is highly unlikely.Secured the aluminum umbrella pole into a vice. Slowly drilled into the pole until I got a hole started. Then slowly applied more pressure and speed. By going slow and steady, the drill bit went through the aluminum pole very easily without an issue. 5/5 stars.

I had to drill lines of holes for 5mm fasteners along the work hardened edges of stamped 3mm thick steel parts. Because the material was so thin compared to the hole diameter, and because 2.4mm pilot holes had been pre-drilled (a mistake), the drill would catch every time it started to break through the material. In spite of having to reverse the drill multiple times and hit the material repeatedly each hole to break through, I got 64 holes drilled with only minor chipping on one flute of a single drill.

I was looking to ease my struggles from using regular bits sizes to metric sizes. No longer having difficulty in making sure the drilled holes match exactlynto my pins. Was exactly what I needed and the price is perfect for my budget.

Bit is straight and sharp. I used this in a drill press to put holes in some aluminum plate (8 ga) and it performed flawlessly. This is not much of a test given how soft aluminum is, so I will update my review after seeing how well it holds an edge on hot rolled steel and other metals.

Perfect! Went through my aluminum bike frame like butter. I use this for riv-nuts. The nuts fit perfectly. Very sharp and good quality!

Item arrived on schedule. I used it to drill through 1/8" 4130 steel which it did with ease and minimal chatter. I could see no wear after drilling four such holes. Not a comprehensive evaluation but it did what I needed.

As described