Hymnorq 7/16 Inch Dia. x 5.51 Inch Long M35 Cobalt Steel Twist Jobber Length Drill Bits 2PC Set, 135 Degree Split Point, Extremely Heat Resistant, for Stainless Steel and Cast Iron

I got these to increase some hole sizes on hardened car suspension components. I read online that other people tended to go through two drill bits for this purpose as the bit would get dull. Not with these! I was able to drill out everything with just a single bit. Recommended if you're needing to work with hardened material. Note that due to the diameter of this bit you'll want to check and make sure that your drill can handle it. Most can, but some compact drills have chucks that won't be able to open wide enough to accept larger bits like this.

I ordered these bits for a custom tooling job. My customer bought one of the very first Shopsmith lathes to ever roll off the factory floor just after WWII. The spindle size on every Lathe manufactured after this first experimental model have 5/8” 20TPI (threads per inch) but on this first model they machined a hardened drill stock 1/2” 24TPI.The customer needs a collar adapter with f 1/2” 24tpi to m1” 8 tpi. After checking the treading bore bit recommended bit size I ordered these bits.They are the perfect size, they cut 440 stainless without too much heat. Though not high speed steel cutters they maintained an edge for a total of 3_1” holes each before needing resharpening and reshaping.While they are not the usual production shop quality they will cut the needed 6 adapter holes and get me by until my new small bore boring bar arrives.I recommend these for the home shop. They cost about 1/10th the cost of professional grade bits and they pull a clean cut when your in a pinch. I ran them at 58’ her second and used lard oil cutting fluid for cooling and flash freeze hardened the surface 50/1000 of the tool after threading.Absolutely perfect size bit for these fine machine threads. I certainly recommend them.

I had to drill 32 holes, 3/8" diameter, in 3/8" thick steel. I bought the five pack of these bits expecting to have to use a new bit every 8 holes (more or less). I did not drill pilot holes, just center punched the steel and drilled. I ran my drill press at 760 rpm, and applied cutting fluid before starting each hole, and each time I cleaned the cuttings away (about six times per hole). I did not apply a lot of pressure, just enough to spin out short spirals of steel. I was able to drill all 32 holes WITH ONE BIT. The bit was not performing perfectly the final four holes, but I thought I would just push it to see. There is damage at the offset point, but the cutting edges are still quite sharp. Very happy, and pleasantly surprised.

Sin problemas Hasta Ahora

Last long and cuts great

These drills dull after plenty of use on dense, exotic wood (ebony, bocote, and so on). However, they lasted longer than I expected. Given the price, I was pleasantly surprised at their performance.

I got these because I had to drill about 20 holes in mild steel tube and 1/4" plate , they worked great. Got 2 and the first ones still sharp, used a little cutting oil with my drill press on 550 rpm and it went right thru the steel. Would by more for job lot quantities. Made in China but 1/2 the cost of expensive bits.

I bought these 1/2" drill bits because I needed to drill a hole through 2 pieces of 1" thick 304 stainless steel. Needed only one bit to do the job. I ran the drill press at 320 RPM and used plenty of cutting oil. Had both holes drilled in about 10 minutes. When I was done I closely examined the tip of the bit I used. It looked as if it were brand new (No kidding!)!!