R_W_B
Senior Member
Ok, I have a full set of taps and dies that I would like to use to clean up the rust and old loctite from all the threads of items I have pulled off my old truck. However I have been told in the past (from various sources) that using a tap to clean threads will cut new material and cause the thread to be loose when reassembled. Various sources told me that a thread chaser was in order for such. You know the kind you see all the time at the auto parts store for spark plug holes, only to buy a whole set they come also in kits.
A set of needed thread chasers (in a kit) will cost me $60. So not wanting to part with $60 right now I did a lot of thinking about this. I could not figure how a tap would cut new material from a hole that was cut with the same size tap.
So I posted this same question on a truck forum and got pretty much a 50/50 mix of opinions. Some for chasers, other said just use the taps. So wanting to get the real truth on it I posted the question on a Machinist forum (yea I belong to a lot of forums).
Amazingly many folks on the machinist forums had not ever heard of a thread chaser. I'm posting the one most convincing reply from the machinist forum below. I welcome comments from you guys on this. But at this point I'm thinking I don't need to buy the thread chaser kit.
====paste from machinist forum===
If the threads are really cruddy and rusty then you will damage the tap, not the thread. The tap acts as it's own lead screw and once it is in one full revolution it is not going to cut anything that is where it should be. If the thread is deformed and material is in front of the cutting edge it will be removed and should be.
If they finding threads looser after cleaning the rust and such out the remember that the rust is part iron and yes it will be looser, but not because of the tap, but because metal has been removed by rusting.
I am in the power generation industry. When we disassemble a turbine we clean every thread. We stard with a wire brush and if that doesn't do it we run a tap or die. It's the last resort because rust and grit will ruin a 500 dollar tap in one hole.
======end of machinist forum paste===
A set of needed thread chasers (in a kit) will cost me $60. So not wanting to part with $60 right now I did a lot of thinking about this. I could not figure how a tap would cut new material from a hole that was cut with the same size tap.
So I posted this same question on a truck forum and got pretty much a 50/50 mix of opinions. Some for chasers, other said just use the taps. So wanting to get the real truth on it I posted the question on a Machinist forum (yea I belong to a lot of forums).
Amazingly many folks on the machinist forums had not ever heard of a thread chaser. I'm posting the one most convincing reply from the machinist forum below. I welcome comments from you guys on this. But at this point I'm thinking I don't need to buy the thread chaser kit.
====paste from machinist forum===
If the threads are really cruddy and rusty then you will damage the tap, not the thread. The tap acts as it's own lead screw and once it is in one full revolution it is not going to cut anything that is where it should be. If the thread is deformed and material is in front of the cutting edge it will be removed and should be.
If they finding threads looser after cleaning the rust and such out the remember that the rust is part iron and yes it will be looser, but not because of the tap, but because metal has been removed by rusting.
I am in the power generation industry. When we disassemble a turbine we clean every thread. We stard with a wire brush and if that doesn't do it we run a tap or die. It's the last resort because rust and grit will ruin a 500 dollar tap in one hole.
======end of machinist forum paste===