What is the different between the Core Diameter and Major Diameter of a Thread?
Diameter of a Thread
Accepted solution
@Anonymous wrote:
but as others said ...why are you needing the Min?
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It is a good question. In this posting the minor diameter is assumed 0.471 in.
You should have posted this image in your original problem description.
In any case, you should have been able to use the Measure tool and look at the drawing and do the measurement and equation yourself. Then you should have instantly (at least that is what I did) recognized that it was a common error of user input transposing digits.
But in any case, the entire discussion revealed that you have not received much (if any) instruction on thread nomenclature.
I think this might be one of the most important topics to be fully covered and understood in an engineering design curriculum.
The topic is far more than I care to cover in a forum, so I will only show how I discovered the source of the error in seconds.
The minor diameter chosen depends partly on the material, no? I've got a tap drill chart that shows different tap drill sizes for the same thread, and gives percentages of thread with each size-- very useful when choosing the right drill for Delrin® or aluminum or stainless steel. Of course, if you're using a tap, the minor diameter can't be any less than the tap's minor diameter.
Sam B
Inventor Professional 2016 R3 SP2
Vault Basic 2016 SP1
Windows 7 Enterprise 64-bit, SP1
@sbixler wrote:The minor diameter chosen depends partly on the material, no? I've got a tap drill chart that shows different tap drill sizes for the same thread, and gives percentages of thread with each size-- very useful when choosing the right drill for Delrin® or aluminum or stainless steel. Of course, if you're using a tap, the minor diameter can't be any less than the tap's minor diameter.
Sam B
Inventor Professional 2016 R3 SP2
Vault Basic 2016 SP1
Windows 7 Enterprise 64-bit, SP1
Not really.
The minor diameter is controlled by the specification and that's all there is to it. It has a minimum and maximum value just like any other feature tolerance.
The fact that some materials may require a different drill to arrive at a hole size to fall within the specification is irrelevant
In the OP's case the thread is specified as a UNC-3B, which means exactly the dimensions stated earlier with regard to minor, major and pitch diameters.
Yes, there are charts that show various thread percentages for a given hole size, but to date ( thankfully ) I have never seen a thread callout as a X% thread engagement.
Of course there are cases where the design requires a tighter or looser thread other than the standard specification, but those are designated as a UNS, and each out-of-norm feature of the thread must be clearly specified on the print/CAD file.
And, while we're clarifying, that's the pitch diameter (.4500 – .4548); the pitch is 1/13" = .0769
Sam B
Inventor Professional 2016 R3 SP2
Vault Basic 2016 SP1
Windows 7 Enterprise 64-bit, SP1
In your video in post42 minor diameter 0.417 inch is measured only after creating the hole. Before creating hole how to know the minor diameter of the thread? Is it from the table?
I did that in a way I didn’t know whether it was correct or not. First I created a hole without chamfer and I measured minor diameter of the hole then I went to edit mode and add additional feature chamfer.
