BrianJ said:
I've searched and read up on taps & dies. I found that HSS is the one to get as it'll stay sharper longer.
Good threads
HERE ,
HERE and lastly
HERE .
I will need the taps and dies to chase existing threads, but, will need to be able to cut new threads.
Is there a metric HSS tap & die set that will fit my need? Also, what is the difference between fine & coarse taps?
TIA,
Brian
Brian, first of all, the links you provided above must have a "glitch" in them; they won't "hook in."
Second: your statement;
"
I will need the taps and dies to chase existing threads.."
Needs correction.
This I posted in one of the "Tap and Die" links that kartracer spent a GREAT deal of time collecting.
CHASING EXISTING THREADS
A VERY BIG No, No - using regular taps and dies (or ANY other variety - like carbon) to "Chase Threads!"
Don't do it!
You are destroying the strength of the thread!! As well as the "fit."
Once a thread has been "cut" and a fastener has been used in/on the thread (and loaded/torqued) the "peaks" of the original thread "roll over."
IF a regular tap or die is used to clean this hole/bolt again; it starts to "cut" the thread AGAIN; only now the thread has become oversized. (in it's axial direction) Try it on an old nut and bolt (put them back together again) and you will see what I mean!
The ONLY way to "chase" existing threads is to use
"THREAD CHASER TAPS and DIES!"
The engine builders (pro's) use the thread "chasers" to clean out any leftover thread sealant. (or dirt and grease) Or clean damaged threads on the ends of bolts.
Inexpensive tread chaser tap and die sets are available from Sears, Snap-On, Mac, etc.
If your going to do a LOT of thread chasing, (and in deep holes) ARP makes sets. (or you can buy them individually)
A word of warning about ARP Thread Chaser Taps is; they LOOK like regular taps and can be easily mixed up with your regular taps.
I put a short piece of shrink tubing on the ends so they stand out; and made a special holder for them.