What exactly is the advantage of a three form thread mill?
Any insight on Three Form Thread Mill compared to single form?
Any difference using climb cutting for a thread mill?
On Mon, 2 Jan 2023 15:43:33 -0700
Bob La Londe <none@none.com99> wrote:
<snip>
What exactly is the advantage of a three form thread mill?
Seeing you didn't get much help with this... I asked "ChatGPT" a couple questions while fooling around with it. Here is the response:
===
Any insight on Three Form Thread Mill compared to single form?
A three form thread mill is a type of tool used in machining to create internal threads, or threads on the inside of a hole. It is called a
"three form" thread mill because it has three different profiles on the cutting end of the tool: one for the root of the thread, one for the
crest, and one for the root radius. This allows the tool to create a
complete thread in a single pass.
In comparison, a single form thread mill only has a single profile on
the cutting end, so it can only produce a partial thread in a single
pass. This means that it takes multiple passes to create a complete
thread, which can be slower and less efficient than using a three form
thread mill.
There are trade-offs to consider when deciding which type of thread
mill to use. Three form thread mills can be more expensive and may
require more precise setup and alignment, but they can be more
efficient and produce a higher quality thread. Single form thread mills
are generally simpler and less expensive, but they may require more
time and effort to create a complete thread.
Any difference using climb cutting for a thread mill?
Climb cutting is a machining technique in which the direction of the
cut is opposite to the direction of the tool's rotation. This can have
a number of benefits, including a smoother finish on the workpiece,
reduced cutting forces, and longer tool life.
When using a thread mill to create internal threads, climb cutting can
be particularly useful because it allows the tool to enter and exit the
cut more smoothly. This can help to reduce the risk of tearing or
chipping on the entry and exit of the cut, which can be a problem when
using a traditional threading tool such as a tap.
However, it is important to note that climb cutting with a thread mill
can also be more challenging and may require more skill and experience
to execute properly. The cutting forces can be higher when climb
cutting, so it is important to use appropriate tool holding and
workholding methods to ensure that the tool does not deflect or
chatter. It may also be necessary to use a slower feed rate and/or a
lighter depth of cut to ensure that the tool does not become overloaded
or break.
===
I don't have a mill... hadn't heard of "Three Form" before so I was a
bit curious myself ;-)
On 1/6/2023 2:34 PM, Leon Fisk wrote:
On Mon, 2 Jan 2023 15:43:33 -0700
Bob La Londe <none@none.com99> wrote:
<snip>
What exactly is the advantage of a three form thread mill?
Seeing you didn't get much help with this... I asked "ChatGPT" a couple
questions while fooling around with it. Here is the response:
===
Any insight on Three Form Thread Mill compared to single form?
A three form thread mill is a type of tool used in machining to create
internal threads, or threads on the inside of a hole. It is called a
"three form" thread mill because it has three different profiles on the
cutting end of the tool: one for the root of the thread, one for the
crest, and one for the root radius. This allows the tool to create a
complete thread in a single pass.
In comparison, a single form thread mill only has a single profile on
the cutting end, so it can only produce a partial thread in a single
pass. This means that it takes multiple passes to create a complete
thread, which can be slower and less efficient than using a three form
thread mill.
There are trade-offs to consider when deciding which type of thread
mill to use. Three form thread mills can be more expensive and may
require more precise setup and alignment, but they can be more
efficient and produce a higher quality thread. Single form thread mills
are generally simpler and less expensive, but they may require more
time and effort to create a complete thread.
Any difference using climb cutting for a thread mill?
Climb cutting is a machining technique in which the direction of the
cut is opposite to the direction of the tool's rotation. This can have
a number of benefits, including a smoother finish on the workpiece,
reduced cutting forces, and longer tool life.
When using a thread mill to create internal threads, climb cutting can
be particularly useful because it allows the tool to enter and exit the
cut more smoothly. This can help to reduce the risk of tearing or
chipping on the entry and exit of the cut, which can be a problem when
using a traditional threading tool such as a tap.
However, it is important to note that climb cutting with a thread mill
can also be more challenging and may require more skill and experience
to execute properly. The cutting forces can be higher when climb
cutting, so it is important to use appropriate tool holding and
workholding methods to ensure that the tool does not deflect or
chatter. It may also be necessary to use a slower feed rate and/or a
lighter depth of cut to ensure that the tool does not become overloaded
or break.
===
I don't have a mill... hadn't heard of "Three Form" before so I was a
bit curious myself ;-)
That's funny. I just watched a video this morning about one of those Chat-AI programs and the lemon law in Michigan. Of course by a Michigan lemon law attorney. I have to say, I have as much issue with this
response as he did with the Michigan lemon law response. LOL.
Some of it may be choice of definitions, but either way some of it is
just not right. I make complete threads that the target machine screw
will thread into with a single form thread mill in just ONE (1) pass.
One can assume with some reasonable degree of certainty that if one is
thread milling (which is done by spiral interpolation) that the machine
has relatively low backlash or is very heavy and climb milling is not
even something one worries about. Therefore in respect to thread
milling the primary relationship to climb milling is that it allows you
to cut the threads from the bottom of the hole to the top avoiding any
chance of chip re-cutting when cutting standard right hand threads. Even
with blind holes.
As to the definition of the three form thread mills that sounds mostly
like guessing. The ones I have seen just appear to have three teeth the same in each flute. This is why I can't see any benefit. At the start
all three teeth cut, but than after the first interpolation only the
lead tooth would be cutting. Even if a second or third pass or spring
pass was required in hard material I don't see how those other same
teeth would be any help. The first one does all the work.
Video single form thread milling I do everyday. 10-32 thread 0.495"
deep. That particular thread mill has done hundreds if not thousands of holes.
https://www.youtube.com/watch?v=fLjfZ7vf4FI&t=55s
On Mon, 2 Jan 2023 15:43:33 -0700
Bob La Londe ... wrote:
<snip>
What exactly is the advantage of a three form thread mill?
Seeing you didn't get much help with this... I asked "ChatGPT" a couple questions while fooling around with it. Here is the response:
===
Any insight on Three Form Thread Mill compared to single form?
A three form thread mill is [...] called a "three form" thread mill
because it has three different profiles on the cutting end of the
tool [...]
Any difference using climb cutting for a thread mill?
Climb cutting is a machining technique in which the direction of the
cut is opposite to the direction of the tool's rotation. [...]
Leon Fisk ... wrote:
On Mon, 2 Jan 2023 15:43:33 -0700
Bob La Londe ... wrote:
<snip>
What exactly is the advantage of a three form thread mill?
Seeing you didn't get much help with this... I asked "ChatGPT" a couple
questions while fooling around with it. Here is the response:
===
Any insight on Three Form Thread Mill compared to single form?
[Then chatGPT says:]
A three form thread mill is [...] called a "three form" thread mill
because it has three different profiles on the cutting end of the
tool [...]
Bob's already skepticized about that claim, and in web searches I
didn't find any support for it. I've seen several three form thread
mills where all the teeth look like the same profile, but didn't
find a spec sheet or drawing that spelled it out..
Some reasons for using a multi-form (including three-form) thread mill
are "They can thread faster because they cut multiple grooves in one
pass" [ref 1]; they "excel in internal deep threads and hard-to-cut materials" [ref 2]; they "are designed for threading in hardened
steels and difficult-to-machine materials" [ref 3].
Makes it look like production, tool life, and special cases are what
make multi-form thread mills desirable.
On the con side: Unlike a single-form thread mill they cut only one
pitch. Side loading and horsepower requirement are higher than for single-form.
[1] <https://www.cnccookbook.com/threadmills-and-thread-milling-speeds-feeds/>
[2] <https://sct-usa.com/products/thread-mills/>
[3] <https://www.harveytool.com/products/thread-milling-cutters---tri-form---un-threads>
Any difference using climb cutting for a thread mill?
[Then chatGPT says:]
Climb cutting is a machining technique in which the direction of the
cut is opposite to the direction of the tool's rotation. [...]
Isn't that backwards? Or ambiguous. Eg, ref 1 says of climb milling,
"the tool is [fed] in the direction of tool rotation". Also see ref 4.
[4] <https://www.harveyperformance.com/in-the-loupe/conventional-vs-climb-milling/>
On the con side: Unlike a single-form thread mill they cut only one
pitch. Side loading and horsepower requirement are higher than for
single-form.
Actually this is not correct. In practice I have found that most single form thread mills are only suitable for one thread pitch for me, but if
you look on the manufacturers websites you will find most are listed for
a range of thread pitches. Multi form thread mills can only cut one pitch. Whatever the spacing of the teeth is on a flute.
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