If you are working on a detailed job that involves the works of nuts and bolts, a tap and die set should be among the desirable tools. Although many ignore the significance of a set, I suggest not to do that because you never know when these small elements will come into play. The best quality tap and die sets are not necessarily the most expensive or lavish ones on the market either.
As there are so many sets to choose from, you can easily end up getting the wrong or inappropriate set. So, I’ve put together a comprehensive list of the top ten tap and die sets with critical reviews of them plus a practical buying guide.
We Handpicked and Tested 10 Best Tap and Die Sets
We have put together a comprehensive product list and review of each set. This will make it easier for you to compare and decide upon the right choice.
01 GearWrench 3887 75-Piece (Editor Choice)
This kit provides the most value for the money. Its 75 pc carbon steel tools are strong, and durable; and it comes with a gear T-wrench plus adapters.
The case is blow molded so it will not bread easily but store various tape measures. This keeps all of your important accessories for your kit in one place.
The patented Twist Lock Guide System keeps the dies nicely in place and centered for cutting. The system also cuts down on “walk back” of the guide. The handles have auto locking features that facilitate the safe removal of tap adapters.
The product also has a GearWrench lifetime warranty. This warranty covers materials and workmanship. Hex shapes, as well as round shapes, can be worked on by the die adapter
The pass-thru® ratchet along with the socket and its accessories work with the die adapter. The large tap adapter has quick release, thanks to the spring-loaded cap that machinists find so much useful.
Specifications
- Material of Tools Carbon Steel
- Set pieces: 75
- Storage Case: Blow Molded
- Made in USA
- Made By GearWrench
- Weight of Set 7.22 lbs.
- Set Dimensions 11.8 x 3.9 x 19.7 inches
- Set Measurements SAE/Metric
Pros
- Durable blow-molded case
- Large set with a wide variety of taps and dies
- Has both Metric and SAE measuring systems
- Tools are made from carbon steel
- Lifetime Warranty
Cons
- The depth of threaded has limitations
- Not ideal for large industry use
Our Verdict
According to our tests and experience. this is simply one of the most versatile tap and die sets you’ll find today. Because of the 5° ratcheting arc with a reversing lever, it is easy to turn without having to use hand-over-hand type turning. The die adapter also works on both hex and round dies.
Cutting threads is easy due to the smooth back and forth movements afforded by the ratcheting handles and adapters. The set including the case is designed to last and it comes at an affordable price for a 75-unit carbon steel tap and die set.
02 Efficere Best Choice 40-Piece SAE Inch Sizes (Budget-Friendly)
This is not an excellent choice for wood but is definitely good for such metals as brass, copper, cast iron, stainless steel, and more.
This 40 piece kit is excellent value for money with its excellent cutting performance of teeth cut to precision by a CNC Machine. They are then heat treated to 60 HRC (Rockwell hardness). This is the temperature that gives the desired results for these tools.
The design has tapered coarse taps and dies for both coarse and fine settings. The kit includes all the popular devices and accessories. This makes it versatile with a wide variety base. You can even try rethreading bolts and holes with this choice.
The tools are made from a strong and durable industrial grade GCr15 bearing steel construction. This means that your tools are going to endure all the work and knocks they will take in their heavy duty carry case.
The heavy-duty carry case is smartly designed to keep all the bits inside sorted into their own neat compact. This is one product to look into should you be looking for a cheaper option.
Specifications
- Set pieces 40
- Storage Case Durable Plastic
- Made By Efficere
- Weight of Set 2.95 lbs.
- Set Dimensions 12.8 x 8.2 x 1.6 inches
- Set Measurements SAE
Pros
- Durable strong plastic case
- Good selection of taps and dies
- Tools are made from Industrial Grade GCr15 bearing steel construction
Cons
- There may be problems with the wrenches
- Only SAE measurement system
Our Verdict
This is a high quality tap and die set for sale. Most of the reviews of this product are rated 5 stars. That is a lot of customer satisfaction with this kit. There are also comments on the helpful service when there was a problem and how quickly they got the problem solved. It is not the biggest of kits, but it is a decent size and has most of what you need in it.
03 Irwin 26376 76-Piece (Advanced Choice)
This is a good choice that can also be a nice yet useful gift item for the machinist in your life. The kit is ideal for auto work and for machinery work. It is also great to have around the garage and your house.
The product comes in a case that is both convenient for portability and it stores your tools in neat compartments.
They are great at both industry standards and private standards. This is definitely the tap and die set for professionals. It is made from tough durable steel and is easy to use.
The mechanisms all work together as they should, and the product gets excellent ratings and reviews. Well, now we know why. The machine has both metric and fractional for even more convenience.
It comes with an Energy Star certification and a great user manual. For any problems, they have a help desk that will answer any queries or advise you on any faulty tools.
Specifications
- Set pieces: 76
- Storage Case: Blow Molded
- Made in USA
- Made By Irwin Hanson
- Weight of Set 7.25 lbs.
- Set Dimensions: 20.3 x 13.7 x 3 inches
- Set Measurements: Fractional/Metric
Pros
- Durable Plastic portable case
- The set is quite large and contains a nice selection of taps and dies
- Tools are made from High carbon steel
Cons
- Problems with thread alignment
- Sending of incomplete sets or duplicate parts.
Our Verdict
Despite some of the angry reviews over receiving wrong parts in their kit. This is not a bad set for the price. It also carries the Irwin name with it and that counts in America it is an American company. Many complain about the wrench that is included with the system. Be sure to test the product thoroughly when you first get it to ensure that any problems get sorted out sooner rather than later.
04 GearWrench 82812 114-Piece
This GearWrench 82812 is 114 pieces of value for money. It has fixtures for nearly every threading possible. With all the various bits that go with this incredible set you are sure to have what you need on hand when you need it.
This 114-piece carbon steel tap and die kit is durable and it comes with all the patented GearWrench gadgets, warranties, and adapters. There is a durable blow molded case to keep the 40 pieces of the tap and die kit neatly sorted in place. This makes your tools organized, easy to find and carry.
The Twist Lock is ideal for tight spaces as it cuts down on the back walk of the die guide. With a 5-degree ratcheting arc, the reversible lever and superior grips help cut back on hand over hand turning.
The handles are equipped with auto locking handles that safely enable the removal of tap adapters. The carry case is a durable blow molded case designed with a sleeve to fit every one of the 114 bits. The case is easy to pack and carry to wherever you need to take it.
Specifications
- Material of Tools: Carbon Steel
- Set pieces: 114
- Storage Case: Blow Molded
- Made in USA
- Made By GearWrench
- Weight of Set 1.3 lbs.
- Set Dimensions: 21.5 x 14 x 4 inches
- Set Measurements: Metric/SAE
Pros
- Durable blow molded case
- Complete set of Metric and SAE taps and dies
- Tools are made from carbon steel
- Ratchet eliminates hand-over-hand turning
- Lifetime Warranty
Cons
- Not ideal for large industry use
Our Verdict
This is an excellent product by GearWrench that comes with a manufacturer warranty. GearWrench has proven to be quite a competitor in the ever-growing tooling industry. With tap and die sets being no exception to that rule. Their products are made out of high-end carbon steel that is built to last and endure heavy duty use. They seem to take their products reputations seriously and are more than happy to help with any questions.
05 Irwin 26377 117-Piece
ional tap and die sets and it is good value for the money. Made from high carbon steel (HSS), it is durable and built for the long haul. It is a nice sized set giving you plenty of sizing choices. You have a wide variety to choose from allowing you to easily get any threading job you need to be done.
It’s 117 pieces, tough durable case with tool compartments makes this set easy to carry and work with. It keeps all the kit bits neatly organized as each bit fits into its own sleeve.
The case is made out of high-quality durable plastic that is built to last and take a good few knocks on its journeys with you. It includes parts such as drill bits, spiral screw extractors and adjustable wrench amongst a few of the many items that come with the kit.
Specifications
- Material: High Carbon Steel
- Set pieces: 117
- Storage Case: Blow Molded
- Made By Irwin tools
- Weight of Set 10.35 lbs.
- Set Dimensions: 22.5 x 14.5 x 3.8 inches
- Set Measurements: Fractional and Metric
Pros
- Durable tough carry case
- Good choice of dies and taps
- Has both Fractional and Metric measuring systems
- Tools are made from steel alloy
- Manufacturer’s Warranty
Cons
- Some quality control issues on the dies and taps
- Not ideal for large industry use
Our Verdict
This product comes with mixed reviews and is a product that you either love or hate. They seem to have had some early issues with their product control such as duplicate sizes, imperfect tap and dies.
But it has seemed to have been sorted out and the customers mostly give it a five-star rating. The customer service is quite good and the company is more than happy to sort out any imperfections or issues you may have with it.
06 TEKTON 7559 39-Piece
This is one of the finest choices from TEKTON. The set is made from milled alloy tool steel which has been designed to last and endure the toughest of challenges. It comes with 3- and 4- plug taps and dies these are for use with hand threaded applications.
It has various sets of taps and dies in the kit including taps and dies that are easily started due to their tapered coarse and fine edges. These will also prevent you from over-threading.
It comes with a durable tightly sealed carry case. The individual sleeves in the case are for placement of each part to keep the set neatly organized, easy to carry and transport. You can thread PVC with it but threading pipe is not possible unfortunately.
Specifications
- Set pieces: 39
- Storage Case: Durable Plastic Case
- Made By GearWrench
- Weight of Set 3.04 lbs.
- Set Dimensions: 12.8 x 8 x 1.8 inches
- Set Measurements: Choice of SAE or Metric
Pros
- Durable Plastic case
- Smaller set with a good choice of tools
- Choice of either Metric and SAE measuring systems
- Tools are made from milled alloy tool steel
Cons
- There may be a casting flaw in the tap chuck
Our Verdict
This is a fine product for a first time tap and dies kit. It has the potential to be added to as parts are usually readily available on the internet. The product does, however, have a few minor flaws such as some of the handles may be a bit finicky. But it is perfect for the milder duty tasks than the heavy-duty ones. They are great for around the house, garden, and garage.
07 ABN Tap & Die Set 60-Piece
This is a well-priced set that is great value for money. It has quite a few parts that are more than enough to get you started.
Designed from hardened alloy steel this product is really tough and the comprehensive kit is designed to meet all your cutting and renewing thread needs. Their precision design makes the ability to easily cut aluminum, copper, brass, stainless steel, cast iron and steel to name but a few.
It incorporates both metric and SAE standard tap for convenience.
Auto Body Now is a company in South Dakota that is a family owned and run a business. Their products are of the highest quality and they provide the Midwest with over 50 000 online sales per month. Their loyal repeat customers stand testament to their reliable high-quality products.
They provide fast friendly service and are always happy to help and sort out any problems as fast as possible. For anyone buying their first tap and die kit, this set should be on your list to check out unless you are preferring a left hand set.
Specifications
- Material: Hardened Alloy Steel
- Set pieces: 60
- Storage Case: Heavy Duty Plastic Blow Molded Case
- Made in USA
- Made By ABN
- Weight of Set 1.96 lbs.
- Dimensions 16.5 x 9 x 1.8 inches
- Set Measurements SAE/Metric
- Set Contains Thread Gauge, Tap Handle, Die Handle, Small tap chuck, Metric tap and dies, Fine and coarse threaded and numbered taps and dies, Fractional taps and dies.
Pros
- Durable case with compartments for tools
- Large set with a good selection of tap and die tools
- Has both Metric and SAE measuring systems
- Tools are made from hardened alloy steel
- 1 Year Manufacturer’s material defects warranty
Cons
- There may be a slight problem with tap and die, holder
Our Verdict
For a long-lasting tap and die set, this set is real value for money. There are hardly any negative reviews on this product, and it can be used anywhere in the house, garage, hobby shop and on your automobile. The carry case is sturdy and will keep all the bits neatly organized and easy to carry around. The support staff is friendly and helpful for any problems that may arise.
08 GearWrench 3886 40-Piece
This 40-piece carbon steel tap and die kit is durable and it comes with a gear T-wrench plus adapters. Durable blow molded case to keep the 40 pieces of the tap and die kit neatly sorted in place This makes your tools organized, easy to find and carry.
The “Twist Lock guide system” is a patented system that keeps the dies centered in place for cutting. The guide minimizes walk back for a more accurate cut. The auto-locking handle features are excellent for enabling the safe removal of tap adapters.
The die adapter works on both Hex and round shapes with perfect ease while the jumbo tap adapter has a spring-loaded lid for quick release. The pass-thru® ratchet, the socket and its extensions work fine with the die adapter.
Specifications
- Material of Tools Carbon Steel
- Set pieces: 40
- Storage Case: Blow Molded
- Made in USA
- Made By GearWrench
- Weight of Set 1 lb.
- Dimensions: 12 x 7 3 inches
- Set Measurements: Metric
- Set Contains 17 Dies, 17 Taps, Metric Set.
Pros
- Durable blow molded case
- Tools are made from carbon steel
- Ratchet eliminates hand-over-hand turning
- Lifetime Warranty
Cons
- Not ideal for large industry use
- Only the metric measurement system
Our Verdict
This set has a 5° ratcheting arc and reversing lever that makes it easy for use without having to use hand over hand type turning. This set and its case are made from high-grade materials designed to last. They are tough and ideal for the workshop and garden. The die adapter also works on both hex or round dies. The ratcheting handles and adapters make for a smooth back and forth motion.
09 Efficere Best Choice 40-Piece Metric Sizes
Made from premium steel alloy the tools are hardy and strong being industrial grade GCr15.
Their precision machined teeth have been treated with Rockwell 60 HRC for good quality threading. It has a strong and durable carry case with molded insides with a pocket for each tool in the set.
This tap and die set is great for designing new nuts and bolts as well as for the repair of damaged threads. The taps and dies will cut most metals, such as brass, carbon steel, aluminum, cast iron, stainless steel, and even copper.
This top rated 40-piece set has more than enough tools in the kit to get you started and is ideal for medium to light tap and die applications. You can use this tap and die set for threading applications in the home and garage. They are also useful for jewellers, watchmakers, and gunsmiths to work on various types of steels and aluminums.
Specifications
- Material of Tools: Premium Steel Alloy
- Set pieces: 40
- Storage Case: Heavy Duty Storage Case
- Made By Efficere
- Weight of Set 3.1 lbs.
- Dimensions: 12.8 x 8.1 x 1.8 inches
- Set Measurements: Metric
- Set Contains: 1 x Long handled adjustable Tap Wrench, 1 x Adjustable Die Wrench, 1 x T-Handle Wrench, 1 x Mini 1/8’ Flat Screwdriver, 1 x Thread Pitch Gauge, 17 x Taps (various sizes), 17 x Dies (various sizes)
Pros
- Durable Heavy-Duty Case
- Large set with wide variety of taps and dies
- Tools are made from steel alloy
Cons
- Reports of burs on the finished threads
- Taps may not be very hardy
- Not ideal for large industry use
Our Verdict
This is not recommended as an automotive tap and die set. But for not-so-heavy-duty work it gives about standard cutting performance. The taps are tapered coarse or fine. The dies do thread quite easily and smoothly this can prevent over threading.
It is a nicely compiled kit with most of all the tools, taps, dies and accessories required for tap and dies work. The customer service is quite good should there be any problem with the tools.
10 TEKTON 7561 45-Piece
This set is real value for money made from the tungsten alloy. It is ideal for the cutting of new threads and bolts. It has various flute plug taps for hand threading as well as the dies needed for this type of application.
The set comes with taps that are both coarse and fine that prevent over threading by being able to start easily.
It comes in a heavy-duty carry case designed to carry the full 45 pieces that come with the set. This set is well known for being able to chase those damaged nuts and bolts. With correct lubrication taps and dies can cut aluminum, brass, cast iron, stainless steel, cast iron bronze, and even brass.
The product comes with a product warranty and fast, friendly support services that are more than happy to help should there be a problem.
Specifications
- Material of Tools: Tungsten alloy high-speed Steel
- Set pieces: 45
- Storage Case: Heavy Duty Storage Case
- Made By Efficere
- Weight of Set: 13.23 lbs.
- Dimensions: 14.2 x16 x 2.8 inches
- Set Measurements: Metric
- Set Contains 1 x 1” T-handled Tap Wrench, 1 x T-handled Die Stock, 1 x ¼”, T-Handle Tap Wrench, 1 x ½” Die Stock adapter, 1 x Screwdriver, 20 x Taps, 20 x Split Dies.
Pros
- Decent sized set with all the necessary components
- Tools are made from steel
Cons
- The case is not heavy duty and may have sealing problems
- Some of the T-handles may have a slipping problem
Our Verdict
This set is value for money, and it gets quite a good number of positive tap and die set reviews. It is wise to keep the tools a little oiled with maybe a few dabs grease. This may be wise to do when tapping as well. There are two types of threads that come with this set and it is great for most light-duty projects. It also comes with all the basics required to get started with it.
Understanding the Tap and Die Set
A tap and die set is used to make the screw head of a nut. The process is done by using various materials called threading. The set comes with an array of tool sizes as well as a device called the chaser. The chaser is the tool used to make old nuts and bolts new and usable again. This process is called chasing!
Tap (Taper Tap, Second Tap, Plug Tap)
The tap is what creates the nut or female portion of the set. They are the long metal shafts with a fluted edge. They cut into the material to create a thread and are made from tempered steel. The top of the tap has a square head where the wrench is fitted onto.
There Are Different Types of Taps:
- Taper Tap
This would be the first tap you’ll use for the initial threading. It looks like a screw and is what determines the size of the thread being made
- Second Tap
This is the second tap that would be used in creating the thread. It does look similar to the Taper Tap but only the first six threads are usually functional on it. It also has more of a tapering head as it’s used to deepen the thread.
- Plug Tap
This tap is the final tap stage of the process and is used to polish up the thread in readiness for the bolt.
Die (Circular Die, Two-piece Adjustable Die, Die Nut)
- Circular Die
This type of die is the easiest of the three to use. It is also the most common of the dies in the tap and die set. The use of this die is for threading in a clockwise direction and is usually a single motion. This die does not have a lot of adjustments.
- Two-piece Adjustable Die
This die allows for quick and easy custom threads with this two-piece die that’s easily adjusted.
- Die Nut
This die is a little confusing as it is actually used as more of a chaser. The die nut refines and sharpens an existing thread. They are not used to make new threads.
What is a Tap and Die Set Used for?
There may be old bolts that need to be removed. Or you may want to breathe new life into some old ones for being reused. A tap and die set can be used to both remove old bolts and get them into a state that they can be reused. If this is all you are needing the tap and die set, there are sets for this purpose.
Anyone who has every bought bolt knows that they come manufactured in set sizes. There may not be a size that fits your particular project. With a tap and die set you can create your own customized from a metal rod.
There are times when you need to have threaded holes in various places to accommodate a bolt. For instance, on the car for fitting a custom trailer hitch. The tap and die set is the kit you will need to do this with.
Tap and Die Set Buying Guide: How to Choose
1. Build Material
The tap and die set need to be made out of sturdy steel. You can get a good quality tap and die set for a good price. I may mean going for a smaller set to start off but at least you can add on and your tools will last. Buying tools made of inferior materials will only cost you in the long run. The best tools to go for are made from steel alloy or Titanium which is a popular choice for many other tools.
2. Size
You are going to want to get a set that has multiple sizes in order to use it on multiple applications. When buying the kit check that they have parts for it or at least generic parts that are made from the same material. They must fit your kit and be readily available when you need them. There is nothing worse than buying a kit only to find there are no extra parts for it.
3. Tap Variety
Make sure the set comes with at least the three basic taps; i.e., the tapper tap, second tap, and plug tap. Aside from bottoming taps, these are important for making clean and clear threads.
4. Wrenches
If the set does not come with a wrench you are going to need to buy one. A good gear wrench will fit most of the taps.
5. Metric/SAE
Some kits come with SAE measurements; this is mostly United States measurements whilst Europe uses the metric system. The best is to look for tools that do both Metric and SAE that way you are never caught out of having to convert measurements.
6. Carbon Steel or High-Speed Steel
Carbon Steel is about the best bet for tools that are going to be the most durable as it is strong steel and will not bread easily.
High-Speed Steel is excellent for creating nuts and bolts but more on an industrial scale. This steel can get expensive to use.
Carbon Steel is the best for non-industrial use.
7. Quality of the Case
You are going to want to check out the case and make sure it is made of strong durable material. The case, as explained above, is really important with this. Each part has a place, so it not only keeps them organized but in one safe place too.
8. Accessories
You are going to want to get a T-Handle and a tap wrench. Make sure that both are made from the same strong materials that the whole set is made of.
9. Warranty
Always make sure the product has some form of warranty. That way if anything goes wrong with the set that is not your fault you have a bit of a guarantee on the product. Most of the high-quality tap and die sets come standard with these.
10. Budget
Check the price range of the products and buy the best quality at the price you can afford. As stressed before, it is better to buy a smaller kit and don’t compromise on the quality of your kit.
11. Threading
Each tap and die set is tested to see the quality of the threading it makes. The threads must be clean and straight without any burs. The bolts and nuts must be solid and able to hold what they are made to hold in place. The wrenches must be strong and durable without falling apart after one or two applications. It must be easy to use and eliminate hand over hand turning as much as possible as well as having minimal walk-back.
12. Carry Cases
The carry case must be able to take the knocks and bumps it is going to endure. The seal must be tight enough to keep the items securely in the case but also not a problem to open. The plastic must not fall apart after a short time period and we prefer cases that do not have any Perspex windows as these tend to break.
A Word from Drillly
You should choose a thread maker tool set based on your individual needs. You should focus on quality and budget to be able to figure out the best toolset for you. Big fancy sets are not always what you are going to use. Rather, go with what you need and then add on if the need arises. No use in getting something you are not going to get any use out of.
A smaller set may mean you are getting better quality that’s going to last longer. It will also be better for your budget but just make sure the set is one that you can expand on. Remember to find out how readily available spares and other parts are for the set.
We would also like to mention that the Drillly team picked products based on our experiment. But that does not mean that those models and brands that could not take a place in this list are of the poorest quality. They were simply not good enough to compete with our top 10 choices.
However, there’s still more to the question – who makes the best taps? Brands like Greenfield, Vintage Craftsman, Norseman, Cobalt, Matco (TDK51), Frost, Volkel, Viking, Dormer, P&N Tools Australia, Performance Tool, Greenlee, Northern Tool, Magna, Mac Tools, Autozone, Klutch, Kobalt, Draper, Champion Cutting Tool Corp, Surebilt, Dayton, Union Butterfield, Vermont American, Morse Cutting Tools, Ridgid, Pittsburgh, Presto, Maximum, Stanley, Cornwell, Westward, Starrett, Buffalo, and Blue Point are also known to manufacture quality taps and dies; while Snap On is known for their TDTDM500A, TD2425, and TDM117A models.
Thread Form Symbols
ACME 60° – STUB 60° Stub thread form
ACME STUB – Stub Acme thread form
ACME-C – Acme thread – centralizing
ACME-G – Acme thread, general purpose
ANPT – Aeronautica National Form taper pipe thread
AWWA – American Water Works Association
BA – British Association Standard thread form
BSF – British Standard Fine thread series
BSPP – British Standard Pipe Parallel
BSPT – British Standard Pipe Taper
BSW – British Standard Whitworth
MM ISO – Metric thread form
N BUTT – American Buttress screw thread
NC – American National Coarse thread series
NEF – American National Extra-Fine thread series
NF – American National Fine thread series
NGO – American National gas outlet threads
NGT – American National gas taper threads
NH – American National hose & fire hose coupling
NM – National Miniature thread series
NPS – American Standard straight pipe thread
NPSC – American Standard straight pipe thread in couplings
NPSF – American Standard internal straight pipe thread (dryseal)
NPSH – American Standard straight pipe thread for hose couplings & nipples
NPSI – American Standard intermediate straight pipe thread (dryseal)
NPSL – American Standard straight pipe thread for locknuts
NPSM – American Standard straight pipe thread for mechanical joints
NPT – American Standard taper pipe thread
NPTF – Dryseal American Standard taper pipe thread
NPTR – American Standard taper pipe thread for rail fittings
NS – Special threads of American National Form
PTF – Dryseal SAE Short Taper pipe thread
SGT – Special Gas Taper thread form
SPL – PTF Dryseal Short Taper Pipe thread
STI – Special Threads for Helical Coil Wire Screw Thread Inserts
UN – Unified and American thread series
UNC – Unified and American Coarse thread series
UNEF – Unified Extra Fine Thread Series
UNF – Unified National Fine Thread Series
UNIV – Unified Miniature Thread Series
UNJ – Unified Thread Series with Controlled Root Radius
UNJC – Unified Coarse Thread Series with Controlled Root Radius
UNJF – Unified Fine Thread Series with Controlled Root Radius
UNR – Unified Constant Pitch thread series with Controlled Root Radius
UNRC – Unified Coarse Thread Series with Controlled Root Radius
UNRF – Unified Fine Thread Series with Controlled Root Radius
UNS – Unified and American threads of selected special diameters and pitches