how to use a thread file

[Bruce Turner]

There must be someone that uses a thread file

 

[bonneyman]

I've got a couple. Rarely did they work on steel bolts, but I had alot of plastic fittings on drain pans that would have been a pain to replace (or a long wait time) that the tools got me through. I think they'd work good on brass and aluminum fittings, too.

 

[OccupantRJ]

Welcome.
That would be me.
On a square thread file the numbers on it are the various thread pitches available to use. Physically place one side of the file to the threads until they properly match. Once matched, push the file across the threads to correct damaged areas of thread. Push forward only, not a sawing back and forth action.

 

[WILD-BILL]

They aren't made to cut threads (in case you weren't aware). They are made to reshape existing damaged threads. I typically would lock the head of the bolt (if loose) in a vise and work the damaged area. Rotating as needed to clean the entire thread diameter.

They work, But man is it a slow painstaking process

 

[Private Lugnutz]

^ What @OccupantRJ and @WILD-BILL said.

Only two things I would add.

I often do much better using a thread gauge, rather than trial and error with various sides of a thread file, to get the right pitch. I find the thread gauge blades to be a cleaner more viewable fit than the teeth on the file.

I've had good results with thread chasers (dies, or restorers), too.

 

[bmwrd0]

Die style chasers are good, but only on standard pattern bolts. If you have anything with an odd size/TPI, such as 1-1/4 12, then you are SOL, and that is were thread files shine.

 

[Private Lugnutz]

Yup.

 

[jumbojak]

I've always had much better luck with triangle files. Thread files never seem to do much of anything for me.

 

[RTM]

I like to start gently, trying to push first rather than cut, but take 2-3 passes to get it right. I do lots of work on old WW tools, and weird thread sizes are the norm.

Another good tool is a Japanese saw Feather File. Can be used to cleanup a single thread at a time, which can make the thread file work easier