how to choose the right tap and die?

[NA97GT]

I broke the threads on one of my exhaust flange nuts and want to run a die over the stud to fix the threads. How do I choose the right die to use, the bolt is 18mm and has course threads?

if the bolt head is 18mm does that mean that the die will also be 18mm?

 

[203Cree]

Buy a thread gauge. Looks like a feeler gauge, but it has the different thread patterns on it. Usually comes with a T&D set, but you might be able to get one separate.

Or if you have the piece of stud you broke, take it to your local hardware store, they'll be able to hook you up.

 

[NA97GT]

the stud did not snap off, it is still in tact. The threads on the nut just got bent, and I think that the stud threads may be bent as well.

 

[ThinkTwice]

Buy a thread gauge. Looks like a feeler gauge, but it has the different thread patterns on it. Usually comes with a T&D set, but you might be able to get one separate.

Or if you have the piece of stud you broke, take it to your local hardware store, they'll be able to hook you up.

+1 on picking up a thread gauge. However, once you've managed to strip or bend a few threads, they'll never form back the same way again, especially if they've managed to strip away under the thread minor diameter.

 

[dirtydave289]

If it's anything like my flange (not sure what car you've got, but I had the same problem) It's a little too tight up there to easily use the thread gauge. Take the nut to a parts store and get the size (ex. 10 x 1.25) then just find a die that size. Will probably be hard. Lowes/Home Depot only sold the size I needed in a set.

 

[203Cree]

If it's anything like my flange (not sure what car you've got, but I had the same problem) It's a little too tight up there to easily use the thread gauge. Take the nut to a parts store and get the size (ex. 10 x 1.25) then just find a die that size. Will probably be hard. Lowes/Home Depot only sold the size I needed in a set.

ACE generally has singles, and they have a "cheater board" do use exactly as you're describing.

 

[Got Boost?]

I broke the threads on one of my exhaust flange nuts and want to run a die over the stud to fix the threads. How do I choose the right die to use, the bolt is 18mm and has course threads?

if the bolt head is 18mm does that mean that the die will also be 18mm?

The size of the socket that the bolt head takes is not how the threads of the bolt are measured. For example if it takes an 18mm socket, the thread size is probably 12 or 14mm. Be sure to get the correct thread pitch (coarseness) as well. Even if the diameter is correct, it will still cross thread if the pitch is wrong.

 

[Ry_Trapp0]

side note, i would suggest getting a set of thread chasers, as a tap/die can **** threads up since it's designed to cut new threads..

 

[Posi]

side note, i would suggest getting a set of thread chasers, as a tap/die can **** threads up since it's designed to cut new threads..

Not if you typically start them as far as you can by hand. Typically on die's there's a starting side to them also which helps.

OP take your nut (lol) to any store with a good selection of bolts. Find the right one that fits. Go to Napa and buy the appropriate die and then go chase those threads. Like I said though be careful and watch what you're doing. Be sure and use some lube even though you're not cutting to much.

 

[NA97GT]

thanks guys, I'm gonna go to ace hardware and buy the same tap for the bolt that I have. hopefully I will be able to fix the broken threads, otherwise I will have to figure out how to pull out the stud and replace it and I think that would be a pia.

 

[Guy Fawkes]

thread not what I expected

 

[pho_phizzat]

thread not what I expected

no pun intended??

 

[harry gilbert]

Technique is also important, whether cutting new threads or chasing existing ones. After starting the tap or die, only advance about 1/4 to 1/2 turn, then back out 1 turn to let any chips fall free. Otherwise, the build-up of chips tear the existing metal and distort the threads. Don't just crank the tooling all the way down in one pass.

Use thread cutting lube, not just any oil. I have a can of 1940-era sulfur-based lube; smells bad but works great.

 

[Guy Fawkes]

Technique is also important, whether cutting new threads or chasing existing ones. After starting the tap or die, only advance about 1/4 to 1/2 turn, then back out 1 turn to let any chips fall free. Otherwise, the build-up of chips tear the existing metal and distort the threads. Don't just crank the tooling all the way down in one pass.

Use thread cutting lube, not just any oil. I have a can of 1940-era sulfur-based lube; smells bad but works great.

hmmm 1940, so when you were still in high school? lol just messing with you man. Good to know though, and makes sense.

 

[harry gilbert]

hmmm 1940, so when you were still in high school? lol just messing with you man. Good to know though, and makes sense.

No, passed down to me from my father, who was a master toolmaker. My first hand tools for wood working were an adze, a spoke shave, and brace and bit. When I was in high school, I inherited the South Bend lathe with tool post grinder. All manual set up; no auto gearbox. Dad made me grind my own bits out of square stock, and heat treat them afterward.

I still have a can of real whale oil, used for lubricating clockworks and fine mechanisms.

 

[Guy Fawkes]

No, passed down to me from my father, who was a master toolmaker. My first hand tools for wood working were an adze, a spoke shave, and brace and bit. When I was in high school, I inherited the South Bend lathe with tool post grinder. All manual set up; no auto gearbox. Dad made me grind my own bits out of square stock, and heat treat them afterward.

I still have a can of real whale oil, used for lubricating clockworks and fine mechanisms.

Want to know how I know youre old? You are ranting lulz! But really sounds like youve had the chance to work on some stuff.

 

[harry gilbert]

Want to know how Iknow youre old? You are ranting lulz! But really sounds like youve had the chance to work on some stuff.

Less ranting than rambling. You would be amazed and surprised to know some of the fun stuff I've had the chance to work on (and situations I've gotten into). :rollseyes

Why, I remember...:sleeping:

 

[NA97GT]

what type of lube do I need. Is it expensive, or can I substitute something else. This is gonna be a one time thing.

 

[aaandht]

If I remember right, ATF can be used as lube for cutting threads.

 

[harry gilbert]

The correct lube is typically selected for the metal you are cutting, and whether you are cutting manually or with power tools:

Thread Cutting Oil - RIDGID Professional Tools

General purpose thread cutting lube can be purchased:

Ace® Thread Cutting Oil - Thread Cutting Oil - Ace Hardware

Thread Cutting Oil