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Discussion Starter · #1 ·
One another thread, somone told me to use a thread chaser instead of a tap to clean the portion of the block where the head bolts go into. I went to sears and they had no such thing and could not find it in their computer.

Where can I get one? Is it that important I use one as opposed to a tap?
 

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To my limited knowledge a thread chaser is used on bolts, gotta use taps on threads in blocks and such.




pittbull7934 said:
One another thread, somone told me to use a thread chaser instead of a tap to clean the portion of the block where the head bolts go into. I went to sears and they had no such thing and could not find it in their computer.

Where can I get one? Is it that important I use one as opposed to a tap?
 

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pittbull7934 said:
One another thread, somone told me to use a thread chaser instead of a tap to clean the portion of the block where the head bolts go into. I went to sears and they had no such thing and could not find it in their computer.

Where can I get one? Is it that important I use one as opposed to a tap?
That is correct, a thread chaser simply cleans/tidies a thread up and is typically used on older bolt holes where the bolt won't go in properly. You can use a tap for this but you have to be very carefull not to cut your original threads up. I have also been met with blank stares when I tried to buy one to chase some spark plug threads on an aluminum head, the local auto places are not the best places to get them. They are available online. I was able to borrow one at a local machine shop.
 

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It's possible to make your own thread chaser by taking a bolt with the correct thread and cutting 3 or 4 vertical slots equidistant from each other on the length of the bolt threads. The depth of the cut should be down to just beyond the minor diameter of the thread.
 

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scrimshaw said:
It's possible to make your own thread chaser by taking a bolt with the correct thread and cutting 3 or 4 vertical slots equidistant from each other on the length of the bolt threads. The depth of the cut should be down to just beyond the minor diameter of the thread.


Just to add a to this, make sure to use a grade 8 or better bolt! Also make sure the slots are evenly spaced and the threads are thoroughly de-burred after the slots are cut, use a soft bolt, poorly cut slots or fail to de-burr and it is very easy to get a home made thread chaser cross threaded in the hole. :pain: It is a good idea with these home made chasers to run a proper sized nut onto the modified bolt several times using anti-seize before attempting to repair any damaged threads with it. Some people may scoff at doing this but I have done it many times and have had really good success with it, the trick is to be careful with the slots and to use a hard bolt and anti-seize.



To repair spark plug threads just go to almost any auto parts and buy a spark plug chaser, it will be double ended with both common thread sizes. This thing is probably no harder than a grade 8 bolt and will not cut threads but with a little anti-seize applied will easily repair most Aluminum head spark plug threads as well as most cast iron heads.
 

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cucumber1949 said:
My understanding is that a thread chaser will clean up the threads without cutting the material while a tap will remove material.


That is the way they work and a thread chaser is much better at repairing damaged threads than a tap or die. With a chaser you will simply be moving metal around and straightening the threads while a thread cutting tap or die will usually do just that-cut the threads-and if you are not very careful with them you can easily remove threads instead of straightening them!
 

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oldred said:
Just to add a to this, make sure to use a grade 8 or better bolt! Also make sure the slots are evenly spaced and the threads are thoroughly de-burred after the slots are cut, use a soft bolt, poorly cut slots or fail to de-burr and it is very easy to get a home made thread chaser cross threaded in the hole. :pain: It is a good idea with these home made chasers to run a proper sized nut onto the modified bolt several times using anti-seize before attempting to repair any damaged threads with it. Some people may scoff at doing this but I have done it many times and have had really good success with it, the trick is to be careful with the slots and to use a hard bolt and anti-seize.



To repair spark plug threads just go to almost any auto parts and buy a spark plug chaser, it will be double ended with both common thread sizes. This thing is probably no harder than a grade 8 bolt and will not cut threads but with a little anti-seize applied will easily repair most Aluminum head spark plug threads as well as most cast iron heads.
Yes, I agree definitely make sure those threads are good before using it. And personally I would spend some time trying to find a proper one before resorting to making my own. Like I said I was lucky and do some occasional work at a machine shop so was able to borrow one. The guys at the auto parts stores really had never heard of it - pretty sad really. Although I did take the borrowed chaser in to the store and he was interested in learning about it, which is something I guess.
 

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scrimshaw said:
The guys at the auto parts stores really had never heard of it - pretty sad really.

If you think finding a thread chaser is bad just try finding a starter (taper) tap. Everyone that sells taps/dies has plug style taps and most will also carry bottoming taps but if you ask for a starter tap 99% of the time they will try to sell you a plug tap, most will tell you it is a starter tap. Sure you can cut new threads with a plug tap, not even hard to do on thin stuff, but a taper tap is soooo, much easier to start new threads with and far less likely to break BUT just try to find one anywhere except a machine tool supply.
 

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Discussion Starter · #13 ·
metalmeltr said:
sears sells a set of them under the craftsman name but the call it a rethreader set.
who else thinks that people that actually work at the store should read the catalog and pay atention to it?

Went to Sears and got it, I think it is called the "rethreading kit" for mechanics.

49.99

the arp kit was 80 and only came with 4 pieces/
 

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jaguarxk120 said:
I listed the ARP kit because it was listed at Summit racing. Heck for $80 you can get a coupla of tap and die sets at HF, when they wear throw them out.
Tap and die sets are not the same as threadchasers. Tap and dies are for cutting threads. As stated above:

cucumber1949 said:
My understanding is that a thread chaser will clean up the threads without cutting the material while a tap will remove material.
 

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Wear safety glasses when using this stuff and especially if you use the HF China made chit. After spending 30 years as a machinist, I think I can say this with for good reason...and we threw away anything that came in from China. If you want to get hurt, use the cheap crap.
 

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The deal is you use this thread restorer tool (aka "thread chaser") for cleaning, deburring and straightening threads, NOT for creating new threads. When cleaning threads, you do not want to undercut the existing threads. Generally speaking, this means no metal removal- except as incidental to cleaning, deburring and straightening the threads themselves.

A decent set will have SAE coarse, fine and metric sized taps and dies for threaded holes or nuts as well as bolts, and should include thread files for SAE and metric sizes (thread files will also allow left hand external threads- like bolts- to be worked with).

The quality can vary a good deal. Some sets look to be either cast or poorly forged- they will have "parting" or "forging" lines running down their length. Obviously, these tools are inferior to a correctly designed and manufactured tool- and their cost will reflect this.

AFA making thread chasers from bolts, fine by me- but the cost in time money and aggravation of fouling up w/one is higher in many cases than the cost of the correct tool set to begin with- the same tool set that you could be using to clean up the threads of the tool you just made.
 

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cobalt327 said:
AFA making thread chasers from bolts, fine by me- but the cost in time money and aggravation of fouling up w/one is higher in many cases than the cost of the correct tool set to begin with- the same tool set that you could be using to clean up the threads of the tool you just made.



Let me add a little more to what was said about the home made chasers, it was meant to be used when a "real" one is not available and it is not in any way a replacement to be used if the real ones are available, I don't think either of us who mentioned these home made ones meant that we should just make them instead of buying them. There are times when a hole or bolt needs some minor repair and a set of chasers are not handy or are difficult to find, such as I think was the original subject of this post. In these cases a home made one can work just fine in a pinch and can get someone out of a bind and it has worked several times for me when I needed one while working out in the boonies, I should have been a bit more clear about what I meant. :spank:
 

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cranky1 said:
Wear safety glasses when using this stuff and especially if you use the HF China made chit. After spending 30 years as a machinist, I think I can say this with for good reason...and we threw away anything that came in from China. If you want to get hurt, use the cheap crap.

You mean those HF 52 piece tap and die sets for $9.95 are no good? :eek:


I got a good laugh when I saw that set at one of their "parking lot" sales and just can't imagine what someone would have to be thinking to waste even $10 on a pile of worthless junk like that! :rolleyes:
 

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oldred said:
it was meant to be used when a "real" one is not available
Understood. :)

just can't imagine what someone would have to be thinking to waste even $10 on a pile of worthless junk like that!
Amen- if you look closely at them, you can see that if they're used as-is, the ragged cutting of the tap's threads will result in MUCH more material being removed (at least from the first times it's used- until the tap's threads are worn down).

The way they're made, the tap's threads are turned, THEN the flutes are cut- but they are then just left as-is, that's to say, the threads of the tap are blocked by the material that's only partially removed when the flutes are cut. Those pieces that are left clogging up the threaded portion of the tap will then break off as the tap's used- to the detriment of any hope of doing a decent job w/them.

Not worth having even if they were free, IMO.
 
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