Forming ("chasing") internal threads?

Snap-On makes this internal thread chasing tool:
<http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID 08&group_ID=1
151&store=snapon-store&dirtalog>
It comes with what seems to be a selection of tips in different t.p.i. but not diameters.
Since there are no diameter specs, I presume that these tips don't span the entire diameter of the hole, but lay against an "arc" of the diameter.
As best I can figure you place the tip (the thread edge) into the threads and kind of scrape the threads. Unlike a tap or a chaser made for a specific diameter threaded hole, this tool seems to rely on a bit of side-force to affect the threads.
How do you use a tool like this?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The name describes it, it chases threads, doesn't originate them in a straight bore. For cleaning goop out of threads, fixing damaged ones and maybe cleaning newly tapped ones. Used as you describe. Beats fishing around with a bent scriber and pieces of paper towel. Would be handy for various automotive tasks where you've got some piece with a non-standard diameter and a standard TPI. From the rather coarse thread sizes, I'd say that's exactly what was intended. Locking rings, retaining rings and the like.
Stan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'd think like a screw driver. Martin
notme wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.