learned the difference chasing & cutting

[A56]

This month, we’re going to look at a tool that is cheap enough to have on hand before you need it and can save you from big headaches and costly repairs. We are, of course, talking about a thread-chasing tap and die set, specifically the kit from Summit Racing (P/N: 900199).

Designed to repair damaged threads (as opposed to cutting new ones), the Summit Racing Complete Thread Cleaning Kit comes with 26 taps and dies designed to clean, restore, and repair common SAE coarse and fine threads. Unlike traditional taps and dies, thread chasing dies do not cut or remove material, but rather reform and smooth out existing thread forms.

The Summit Racing kit comes with 26 different rethreading taps and dies. Look below for the specific sizes included, but there are six coarse-thread and six fine-thread taps, and seven coarse-thread and seven fine-thread dies included in the kit.

We’ve discussed before that dirty or damaged threads can lead to a wrecked block. By simply running thread-chasing taps through the threaded holes in your block, you are sure to not run into any issues when threading in the myriad of fasteners required by your engine. In fact, even if you don’t think there is any damage to the threads, the thread chaser can clean out unseen debris that can lead to issues.

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On the left, you can see the difference between a thread-chasing tap (top) and a thread-cutting tap (bottom). On the right, you can see that the thread-chasing taps have a hex head built in, eliminating the need for a tap wrench, and allowing the use of standard sockets or open-ended wrenches (although, you shouldn't need that much force on the thread chasing tap).

Taps and Dies

Thread-chasing taps and dies have visually obvious design differences. While there are several types of cutting taps, the thread-chasing tap varies in that the threads start immediately, and don’t have the large channels to clear the cutting debris generated by a typical tap. Also, the threads aren’t sharp, as they are designed specifically not to cut.

Sizes Included in the Summit Racing Kit
COARSE THREAD FINE THREAD
Taps Dies Taps Dies
1/4″-20 1/4″-20 1/4″-28 1/4″-28
5/16″-18 5/16″-18 5/16″-24 5/16″-24
3/8″-16 3/8″-16 3/8″-24 3/8″-24
7/16″-14 7/16″-14 7/16″-20 7/16″-20
1/2″-13 1/2″-13 1/2″-20 1/2″-20
9/16″-12 9/16″-12 9/16″-18 9/16″-18
5/8″-11 5/8″-18





The same differences apply to the dies, which can be extremely handy for cleaning up rusty or damaged studs, or even bolts that are hard to find replacements for. Another cool feature of most thread-chasing taps, the Summit Racing kit included, is that you don’t need a tap wrench or tap sockets for the taps. They have built-in hex ends that will work with traditional open-end wrenches and sockets — although you probably won’t need too much mechanical advantage.

Whether you have a specific issue you need to fix, or just want to ensure your block (or any other component with threads) is perfect before assembly, a set of thread-chasing taps are the right tool for the job. And for the price, a set should be in your toolbox, just in case.

For our factory small-block Ford block, we didn’t have any issues ahead of time, but did have some gunk come out of the holes when we ran the 7/16″-14 thread-chasing tap through the head-bolt holes.

 

[toolmanmike]

Yes, thanks for the thread chasers clean and straighten, taps and dies cut new threads. I preached that for 28 years..

 

[Righty Tighty]

Thanks for the education. I've been doing it wrong...

 

[67Dart273]

The only caveat I can add is this:

Thread chasers have been around since before I was born (I'm 73) and back then were made by NAME brand tool companies, the LEAST of which were ones such as KD Tool Most of the brand names that were around "back then" making MACHINE TOOLS I cannot even name anymore

So the QUESTION is this: ARE Chinese imports such as Summit of good QUALITY and are they MANUFACTURED CORRECTLY? That is, to proper form and dimension, and tolerance?

IS THERE a quality brand name manufacturer who sells thread chasers?

"I don't know" offhand

 

[toolmanmike]

The only caveat I can add is this:

Thread chasers have been around since before I was born (I'm 73) and back then were made by NAME brand tool companies, the LEAST of which were ones such as KD Tool Most of the brand names that were around "back then" making MACHINE TOOLS I cannot even name anymore

So the QUESTION is this: ARE Chinese imports such as Summit of good QUALITY and are they MANUFACTURED CORRECTLY? That is, to proper form and dimension, and tolerance?

IS THERE a quality brand name manufacturer who sells thread chasers?

"I don't know" offhand

Lang makes them for most of the resellers including MAC, Snappy, and Matco. Hand Tools - Rethreader Tools - Page 4 - Lang Tools

 

[6PakBee]

Wonder who made my Craftsman set?

 

[RustyRatRod]

GREAT thread! Thanks! You'll find that probably over 90% of what people actually need to do is repair threads, which of course, calls for the chaser set. Only a small portion are actually making new threads in something, such as fabrication and such. That's when you need cutting tools. People often use cutting tools to try and repair threads and end up ruining them because they're already damaged and the cutting tool removes even more.

 

[halfafish]

Thanks for the education. I've been doing it wrong...

Me too. I just ordered a set of the Langs. More expensive than the Summit ones but I know I'll use them a lot and more money for a better product seems like a good idea.

 

[RustyRatRod]

Me too. I just ordered a set of the Langs. More expensive than the Summit ones but I know I'll use them a lot and more money for a better product seems like a good idea.

Which one did you get? The SAE only or the SAE and metric?

 

[halfafish]

Which one did you get? The SAE only or the SAE and metric?

I got the SAE only. It was about $65 delivered. The metric combo was another $30 or so on top of that. My DD is a Subaru, but it's new enough I'm not likely to need to work on it. Everything else I own is SAE.

 

[toolmanmike]

Wonder who made my Craftsman set?

Probably Lang. What does it look like.?

 

[A56]

A thread about threads, go figure.

 

[RustyRatRod]

A thread about threads, go figure.

Dang right.

 

[halfafish]

A thread about threads, go figure.

Now that right there is just plain funny. Well played, sir!

 

[Tooljunkie]

Yes, thanks for the thread chasers clean and straighten, taps and dies cut new threads. I preached that for 28 years..

But i still do it wrong..you realize i need sae and metric, and im cheap

 

[ch1ll]

The only caveat I can add is this:

Thread chasers have been around since before I was born (I'm 73) and back then were made by NAME brand tool companies, the LEAST of which were ones such as KD Tool Most of the brand names that were around "back then" making MACHINE TOOLS I cannot even name anymore

So the QUESTION is this: ARE Chinese imports such as Summit of good QUALITY and are they MANUFACTURED CORRECTLY? That is, to proper form and dimension, and tolerance?

IS THERE a quality brand name manufacturer who sells thread chasers?
"I don't know" offhand

I would say yes if you use name brand cutting tools, lot of quality cutting tools coming out of China and Korea. Thread forming taps are used in high production machining as they have a much greater life span and the strength of the threads are greater. All hardened screws are thread formed, think arp. Not sure how these forming tools would work in cast iron though.

 

[pishta]

Hmm, I always used bottom taps. I agree that chasing the threads on an old block sure makes things go back together easier. Lots of crap comes out of "cleaned" blocks too. Never want to bottom a head bolt in a hole full of rust or worse.