How are these large "split" Snap-On dies used? TD9902B

[3jakes]

I've seen one of these type die before, now I am flipping this Snap-on set (TD9902B) where all but one die is split with an adjust tension screw.
I'd like to know more about this set before it leaves.

Can someone explain to me how this is used?
How do you know when the correct tension or gap is achieved?

 

[cvairwerks]

If I remember correctly, it allows you to set the class fit for the threads.

 

[3jakes]

If I remember correctly, it allows you to set the class fit for the threads.

Ok,
Help the ignorant.
What does that mean?

 

[cvairwerks]

If you look at a thread table, it will give you a range of dimensions for a particular thread size and profile. Within that set of numbers is a fit classification. That classification defines the difference between the internal and external thread dimensions. A loose fit means that things thread together very easy, with little effort and can be easily over torqued causing thread damage or vibrated loose under the right conditions. A closer fit changes the values, sometimes for the betterment of an assembly. There are times though, that too tight of a class raises manufacturing costs unnecessarily and can impact assembly. Lots goes into not only thread profile selection, but fit class too when designing something.

 

[Wamsutta]

Looks to me if you turn the screw in, it's going to cut the threads deeper.

 

[laser3kw]

Looks to me if you turn the screw in, it's going to cut the threads deeper.

^^^^^ in a nutshell

 

[red94chev]

Everything cvairworks said. Here's the basic idea of how to use them.

1. Adjust screw to enlarge the diameter.
2. Cut threads.
3. Test fit assembly to check thread engagement (may not even fit if threads weren't cut deep enough).
4. Adjust screw and re-cut threads.
5. Test again until you get the thread engagement you like for this application.

 

[3jakes]

If you look at a thread table, it will give you a range of dimensions for a particular thread size and profile. Within that set of numbers is a fit classification. That classification defines the difference between the internal and external thread dimensions..

Thanks.
As in many things... "one size does not fit all"
In fact... one size sometimes, does not fit itself.

 

[3jakes]

Everything cvairworks said. Here's the basic idea of how to use them.

1. Adjust screw to enlarge the diameter.
2. Cut threads.
3. Test fit assembly to check thread engagement (may not even fit if threads weren't cut deep enough).
4. Adjust screw and re-cut threads.
5. Test again until you get the thread engagement you like for this application.[/QUOTE

Thanks.

 

[Dingleburry]

Ok,
Help the ignorant.
What does that mean?

Hope you can read this

 

[Htscheg]

Hope you can read this

What book is that page taken from please?

 

[Dingleburry]

What book is that page taken from please?

Audel millwright and mechanics guide
https://www.amazon.com/Audel-Millwrights-Mechanics-Guide-Thomas/dp/0764541714

This link has the table of contents:
https://www.wiley.com/en-us/Audel+Millwrights+and+Mechanics+Guide%2C+5th+Edition-p-9780764541711

 

[larry_g]

http://www.amesweb.info/Screws/AsmeUnifiedInchScrewThread.aspx

The above references the classes of threads. Thread classes are basically how tight the tolerances are and so the split die can be adjusted to set the tolerances you need. In the below link read the three wire measuring procedure or some of the other measuring methods for determining if threads are in tolerance of the class you are trying to achieve. Threads and thread cutting can be quite complicated if you take the time to learn and understand.


https://www.threadcheck.com/technicalinfo/

lg
no neat sig line

 

[Bob P1]

I have never run into a instance where I need one of these...yet!

 

[2oolhound]

I'm not a machinist, engineer etc but I cut a lot of threads and have a few sets of those same dies so this is just my opinion. Info I've gleamed on this subject is the thread classes and Audel's info posted above is too specific for general use and more suited to building intricate precision things with tool steel.

All basic tap and die kits like these from Snap-on, Mac, Hanson/Irwin etc typically are not be made from HSS and will cut threads to 75% nominal dimensions in mild steel. The set you have offers 2 settings, 75% nominal and 60% nominal which is a little looser fit but still very useable for most uses other than high torque applications. The adjustment screw should always be all the way in or out but not in between where it is not locked in position.

If you consider the V shape of a thread and imagine a nut and bolt with the same pitch and dimensions you can see where on paper a single zigzag line would denote the threads for both nut and bolt. However a nut and bolt that shared that same zigzag line for their dimensions would not fit together without a lot of friction. For this reason threads are cut to a percentage of pitch of the nominal size. Aside from this the tips and valleys of the V shape are truncated or chopped off.

When cutting female threads the drill size specified will produce 75% nominal threads. For a 60% nominal, choose the next biggest drill.

For male threads your round stock will be specified (eg. - 3/4", 5/8" etc.) and will yield 75% nominal threads from the die. For 60% form factor you should use undersize round stock which will vary according to the thickness of the stock used but you could use the same dimensions as the next smaller drill size available as a reference on how much to turn down your stock.

 

[rsanter]

If I remember correctly, it allows you to set the class fit for the threads.

Correct. The class of fit defines the gap, play, or space between the internal and external threads.
If you thread a shaft and the fit of the nut on it seems a little too tight you can adjust the die and go again.
For 99.9% of the applications if you don’t know what you are doing then leave it alone

 

[colin39]

Correct. The class of fit defines the gap, play, or space between the internal and external threads.
If you thread a shaft and the fit of the nut on it seems a little too tight you can adjust the die and go again.
For 99.9% of the applications if you don’t know what you are doing then leave it alone

Like button needed,, thank you. It's ok he is on YouTube now watching someone

 

[MShaw]

"HSS and will cut threads to 75% nominal dimensions in mild steel. "
No. the blank size is adjusted to yield a percentage of full thread, Typical threads have the blank size adjusted to provide 70% of full thread when cut to the proper size (Pitch Diameter)

As you get closer to 100% full thread tool life goes down and difficulty of cutting threads goes up. 70% thread has been tested and accepted as providing ease of cutting with minimal loss in strength.

 

[CR888]

Are these dies only supplied or offered in high end machinist style tap & die sets? Or would they be something you would order individually as specialist pieces? Interesting thread.

 

[MShaw]

I just realized that the above statement was in error. The tapped holes have the tap drill size adjusted to produce 70% thread. The externally threaded part is produced with the diameter slightly below nominal size. The actual diameter is determined by the class of thread. Sorry for the mis-statement above.

 

[bob15]

Are these dies only supplied or offered in high end machinist style tap & die sets? Or would they be something you would order individually as specialist pieces? Interesting thread.

You typically buy them in singles. McMaster, MSC, the former Enco would be the type of places to buy them.

remember if you buy them, you need to get a new die holder as well.

 

[kelpaso1]

Another question related to this thread. What is the purpose of this adjustable ring thing on my die holder? Some kind of guide? How do you properly use it?

 

[RVDan]

Geez my SnapOn guy told me you adjust the screw to open it up when trying to start threads on raw bar stock.

 

[LeeG]

Another question related to this thread. What is the purpose of this adjustable ring thing on my die holder? Some kind of guide? How do you properly use it?

Put the die in the holder so the "feed side" is toward that side of the die holder. Adjust the opening on the die holder so it just fits the stock you are cutting the thread in. This will help in keeping the die in line with the stock while you are starting the thread.

Some die holders can be found with a solid tube for the same purpose, but they are limited to a single die size (or small range).

 

[larry_g]

Geez my SnapOn guy told me you adjust the screw to open it up when trying to start threads on raw bar stock.

I understand now why he is a salesman and not a machinist.

lg
no neat sig line

 

[bob15]

Geez my SnapOn guy told me you adjust the screw to open it up when trying to start threads on raw bar stock.

Take anything else he says with a grain of salt, at least in tool-making equipment.

 

[2oolhound]

3jakes, here are photos of some snap-on charts found on my T&D sets you can print. Notice on the bluepoint is states to use the screw all the way in or all the way out but on the newer set it says you can set it in between. I always thought the screw might creep if it was in the middle somewhere. Maybe they reduced the slope of the threads to reduce friction on them.

 

[6PTsocket]

What they said. You can experiment but there are go-no go screw gauges that you can set the die with. My metal work is not of a level that I get into class fit but if the bolt seems too loose or tight, I just use a bolt as a screw gauge and set the die so it just stops cutting.

Sent from my SM-G900V using Tapatalk

 

[RoyArms]

Harbor freight has dies with a split in them as well. Came in handy when fixing the threads on a prop shaft on a boat. Spun the prop off and the steel was too hard to thread a normal hardware store die on, actually broke it trying. Ran the split die on at its loosest setting first and it was no problem to get it cleaned up.