Metric 5% Cobalt Step Drill Bits(4-32mm/15 Steps)

All metal bits are consumable in my opinion. But this one is lasting a really long time. Very sharp, and with proper tap oil cuts very clean holes in aluminum and steel. Price is great, so I’ll buy another in anticipation of eventual failure, and will probably continue to buy more.

I am a Journeyman sheet metal worker (retired). I had my tools stolen and I needed a uni-bit for stainless. Good thing: it starts itself. That first penetration takes a bit of time ( keep the oil up!) but once it does it really rips. Be careful that once the hole is started slow the speed and lighten up on the pressure, Otherwise this will bite hard and possibly warp your work (and hurt your wrist) depending on thickness. I was drilling a 18 ga. backsplash. I got a few minor distortions because this bit bit hard. The trim piece for my faucet covered them. I have had other cobalt bits before but this is the best.

If drilling thru stainless use cutting oil and this will last. This drill did the job.

I needed this bit to set the pilot hole to open up some axle flanges to fit GM metric studs(12mm). I used the 12mm step to pilot the hole then used another regular cobalt bit to drill through. Axle flange was made of hardened steel about 3/8 thick. The bit made quick work of the 10 holes I did. I lubed the hole with cutting oil.

I bought 2 of these expecting both be trash at the end of my project. I had 56 holes to drill into 2 stainless steel cabinets. Hole sizes 14mm 16mm and 22mm. The bit started out cutting through 0.75in thk. 304 Stainless like butter. Figured I would get about 10 holes done before it started to wear. Much to my amazement I was able to complete the job. The last 8 were difficult but only at the 14mm step. All of the other steps were still cutting well. After all said and done only needed 1 bit. 1 thing to be noted. I did not take it easy on the bit. I horsed this through the metal. It got very hot but just kept going.If you ate thinking of buying one. Think no further. Just remember to use a little cutting oil and you will be very happy with the results.

Needed to drill through 3mm Stainless Steel and have varying hole sizes for the task. This bit provided 20 holes at varying diameters. It cut through the first 10 holes with little degradation. The last hole drilled was degraded by approximately 20% from the first, which is better than I had anticipated.What makes this bit great is that it works and provides different diameter drilling with just one bit.

Bought this to install some additional bungs in my exhaust. Does a great job with piping. Haven’t tried anything thick. But it works for small gauge stainless steel.

Was surprise on how well it drilled within a 1/8” steel plate. I did use cutting oil with this bit. For the price it is not too bad. Held up really well.