whateg01
Well-known member
I finally decided to try thread forming taps. So I ordered one. And it arrived. I was expecting to see just a tapered thread, but this has a slot ground in it. Is that normal?
Thread forming taps
- Thread starter whateg01
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Wamsutta
Well-known member
I think that is for restoring threads, not cutting new threads. What brand is it?
LopezBart
Well-known member
Here's a pic from MSC's thread forming taps... I'd guess the edge is there for cleaning up the formed threads.
Wamsutta
Well-known member
So are thread restoring taps and thread forming taps the same thing?
Thread forming taps have been used a lot in production applications for at least the last 20 years. What little I know is that the hole has to be very precise in diameter- and not "I drilled this by hand, or on my drill press". A few thousandths out of nominal for a forming tap is a huge difference in comparison to a cutting tap. Which is why this isn't a thing for a normal DIYer.
APEowner
Well-known member
The groves are for lubrication. You need lots of it flowing in and out of the hole. Use a cutting oil not a mist. Also, you need a larger hole than a standard tap.
Drill Size = Major Diameter – [(0.0068 x desired % of thread) / Threads Per Inch]
Drill Size (mm) = Major Diameter – [(0.0068 x desired % of thread x pitch (mm)]
Drill Size = Major Diameter – [(0.0068 x desired % of thread) / Threads Per Inch]
Drill Size (mm) = Major Diameter – [(0.0068 x desired % of thread x pitch (mm)]
CapriMikeC
Well-known member
The grooves are to prevent hydraulic lock in blind holes. Imagine filling a blind threaded hole with oil and running a screw in at 1000 rpm to the bottom.
Form taps exert a lot of pressure on the workpiece and require good lubrication. There are some form taps that do not have grooves because there is adequate relief for lubricant to move around.
Form taps exert a lot of pressure on the workpiece and require good lubrication. There are some form taps that do not have grooves because there is adequate relief for lubricant to move around.
The slot is for lubrication.
That tap is a thread forming tap, not a "thread restoring tap".
Thread forming taps don't cut the material to make the threads, they "form" the threads (cold deform the material to make the threads).
Done right, formed threads are typically stronger than cut threads (because they are cold-forged into the material and not cut into the material).
Also, no chips are produced during the forming process.
But not all materials are good candidates for using thread forming taps. If the material is brittle or forms a powdery chip when machined (ahem, looking at you cast iron) or is too 'soft' (many plastics) then it is not a candidate for using a thread forming tap.
And they take more power to use than a cut tap. And can distort the material more than a cut tap, requiring either generous chamfers at the entrance and exit of the hole or clean-up after threading.
And thread forming taps require a different starting hole diameter than a thread cutting tap (because of the material flow from the thread forming process).
www.harveyperformance.com
That tap is a thread forming tap, not a "thread restoring tap".
Thread forming taps don't cut the material to make the threads, they "form" the threads (cold deform the material to make the threads).
Done right, formed threads are typically stronger than cut threads (because they are cold-forged into the material and not cut into the material).
Also, no chips are produced during the forming process.
But not all materials are good candidates for using thread forming taps. If the material is brittle or forms a powdery chip when machined (ahem, looking at you cast iron) or is too 'soft' (many plastics) then it is not a candidate for using a thread forming tap.
And they take more power to use than a cut tap. And can distort the material more than a cut tap, requiring either generous chamfers at the entrance and exit of the hole or clean-up after threading.
And thread forming taps require a different starting hole diameter than a thread cutting tap (because of the material flow from the thread forming process).
8 Unique Facts About Thread Forming Taps - In The Loupe
Unlike most CNC cutting tools, Thread Forming Taps, otherwise known as Form Taps, Forming Taps, or Roll Taps, work by molding the workpiece rather than
www.harveyperformance.com
WhoWhatNow
Well-known member
Do these work well with pneumatic tapping arms like a Flex-arm? Do they require more torque than spiral flute taps?