“I was very happy with my purchase of the tough drill bits, they allowed me to drill out some broken off tensile bolts form a 25 year old motorbike cylinder head, failure in this would have meant finding a new head or abandoning the project.”

1 2 npt threadsizes

If you disable this cookie, we will not be able to save your preferences. This means that every time you visit this website you will need to enable or disable cookies again.

“These drills perform exceptionally well. They’re far superior to anything I can buy locally. Delivery is extremely fast. I was able to finish drilling a 3/8” hole through 1-1/4” hardened bar stock. I must have gone through a dozen conventional cobalt bits before purchasing this kit. Love ‘em.”

NPT threaddimensions PDF

“They are fabulous. I still haven’t had the time to use them for their actual intended purpose – drilling out exhaust manifold studs, but I did try them on a couple of bolts to see how they did and was very impressed! Told a bunch of my friends about them. Hoping to get a joint order together. I want more sizes or one of the sets!”

1 NPT threaddimensions in mm

This website uses Google Analytics to collect anonymous information such as the number of visitors to the site, and the most popular pages.

1/4npt threaddimensions in mm

“I’ve been at this a long time and I have never seen bits this good. On my test, they breezed through gr 8 bolt on the press with cut oil. When I tested with a chord drill, I found that you could break the bit if you weren’t perfectly square. On the car with the broken exhaust stud, it was fantastic, they bite like crazy. I’m going to give them as gifts to my wrenching friends.”

You should read our 6 step guide to drilling through metal because the same rules apply to drilling harder grade alloys.

Watch videos of hardened metal being drilled with TTP HARD cobalt drill bits. You will see how easily Hardox 450 can be drilled using the correct speed, pressure and pleanty of libricant paste. Likewise a 12.9 cap head bolt is easily drilled when the drill bit is allowed to do the work and rest periods prevent the drill bit from overheating. Finally you will see a BMW flywheel and even JCB tow plate steel being drilled without any effort using correct speed, pressure and lubrication.

“These drills perform exceptionally well. They’re far superior to anything I can buy locally. Delivery is extremely fast. I was able to finish drilling a 3/8” hole through 1-1/4” hardened bar stock. I must have gone through a dozen conventional cobalt bits before purchasing this kit. Love ‘em.”

1 2 npt threadsize chart

If you can drill metal then certainly you should not fear drilling hardened steel because the same techniques apply. Read below what customers say about their experiences drilling hardened metals and then watch the videos of TTP HARD drills in action.

1/2-14nptdimensions

“I was very happy with my purchase of the tough drill bits, they allowed me to drill out some broken off tensile bolts form a 25 year old motorbike cylinder head, failure in this would have meant finding a new head or abandoning the project.”

“I’ve been at this a long time and I have never seen bits this good. On my test, they breezed through gr 8 bolt on the press with cut oil. When I tested with a chord drill, I found that you could break the bit if you weren’t perfectly square. On the car with the broken exhaust stud, it was fantastic, they bite like crazy. I’m going to give them as gifts to my wrenching friends.”

This website uses cookies so that we can provide you with the best user experience possible. Cookie information is stored in your browser and performs functions such as recognising you when you return to our website and helping our team to understand which sections of the website you find most interesting and useful.

We have selected some customer reviews to give you an idea of some of the hardened metals and steels TTP HARD cobalt drill bits will drill through. You will see that whether you are drilling a hardened 12.9 bolt or an exhaust manifold stud once you follow the basic drilling principles you should have the same level of success.

1/2 npt threaddimensions in mm

Because of allowable tolerance of plus or minus one turn on both the male and female threads, the actual thread engagement length / threads of the assembly will vary from the engagement dimensions shown in the chart which are based on “perfect” threads.

NPT threadchart

You should read our 6 step guide to drilling through metal because the same rules apply to drilling harder grade alloys.

We have selected some customer reviews to give you an idea of some of the hardened metals and steels TTP HARD cobalt drill bits will drill through. You will see that whether you are drilling a hardened 12.9 bolt or an exhaust manifold stud once you follow the basic drilling principles you should have the same level of success.

Watch videos of hardened metal being drilled with TTP HARD cobalt drill bits. You will see how easily Hardox 450 can be drilled using the correct speed, pressure and pleanty of libricant paste. Likewise a 12.9 cap head bolt is easily drilled when the drill bit is allowed to do the work and rest periods prevent the drill bit from overheating. Finally you will see a BMW flywheel and even JCB tow plate steel being drilled without any effort using correct speed, pressure and lubrication.

“They are fabulous. I still haven’t had the time to use them for their actual intended purpose – drilling out exhaust manifold studs, but I did try them on a couple of bolts to see how they did and was very impressed! Told a bunch of my friends about them. Hoping to get a joint order together. I want more sizes or one of the sets!”

If you can drill metal then certainly you should not fear drilling hardened steel because the same techniques apply. Read below what customers say about their experiences drilling hardened metals and then watch the videos of TTP HARD drills in action.

ANSI B1.20.1 Standard provides both “Hand Tight” engagement (L1) and “Wrench Make-Up” (L3) dimensions. The L1 basic hand tight engagement applies to NPTF threads. It is the theoretical length of assembly (hand-tight) if both parts had perfect thread form and taper and were exactly at the nominal size. The diagram and table below show standard L1 lengths (Hand-Tight Engagement) for pipe threads as well as the L3 (Wrench Make-Up). For convenience we have added L1 + L3 which is the total thread engagement when wrench tight.