Metric Threads

[Dupa3872]

Hi guys,
I am up against it on a job and doing what I can to figure this out but looking for some help to confirm what I find. I am cutting a metric thread M50 X 2.0-6G and need to know the Pitch Diameter. I have Mic's for it but no gages. Is there an easy way to calculate this ? I do some Metrics but always find them in the book, this one is not where I usually get my information from and worry I'm going to screw up.

Thanks for any help

Ron

 

[Mtndew]

Let me google that for you

 

[LKeithR]

Let me google that for you

Now that's funny...

 

[Timelord]

Not sure exactly what you are asking, but the pitch diameter of a thread can easily be measured using the 3 wire method. Get a copy of Machinery's Handbook and look up how to do it.

Timelord

 

[michiganbuck]

Here is one site. (haven't checked it out but just off the top it looks like the right numbers.)
Still the tool bit must be correct and properly set to make the check valid.

Three Wire Method Of Measuring Pitch Diameter

http://mdmetric.com/tech/M-thead 600.htm

 

[Dupa3872]

Let me google that for you

Thanks I should have gone here first I was running crazy and looked to you guys for the answer. Much appreciated

Ron

 

[sinha]

But why do you need to know the pitch dia for the purpose of machining?
OD and ID that is all which is required.(plus pitch, of course)

 

[Rapid_Tech]

But why do you need to know the pitch dia for the purpose of machining?
OD and ID that is all which is required.(plus pitch, of course)

How do you plan to measure the ID of an external thread??

 

[modelmakerblue]

But why do you need to know the pitch dia for the purpose of machining?
OD and ID that is all which is required.(plus pitch, of course)

You are so wrong it's not even funny, guess that sums up why we get so many quality products from the far east?

Tony

 

[litlerob1]

You are so wrong it's not even funny, guess that sums up why we get so many quality products from the far east?

Tony

That's not quite fair, in fact Sinha is an extremely competent programmer and designer. But you are right, just not quite fair. I think he is referring to the Minor diameter as the "ID"? @ Sinha, the Minor diameter of an external thread is the least of anyones worries, the Major diameter and the Pitch diameter are what we need to be right.

Robert my ±2

 

[angelw]

But why do you need to know the pitch dia for the purpose of machining?
OD and ID that is all which is required.(plus pitch, of course)

Hello Sinha,
Although he doesn't actually say as much, from the OP's reference to Pitch Diameter and "I have Mic's for it but no gauges", in his opening Post, its clear that he must be referring to using a Thread Micrometer to measure the Thread. With regards to measuring a thread for the purpose determining if its going to fit the mating part (if both are made to conventional standards), neither measuring the Minor nor Major diameter are very effective. A Thread Micrometer, or the Three Wire Method (if the Best Wire Size is used), measures the Pitch Diameter of the Thread. If the Pitch Diameter is within the Tolerance specified by the Tolerance Class being used, then the Thread will fit so long as the Minor and Major diameters are of as size that doesn't create interference. Accordingly, the Pitch Diameter is the most important dimension when determining the fit of a Thread

Regards,

Bill

 

[sinha]

Thank you so much Bill.
There is always something to learn from your posts.
You are not only knowledgeable, your attitude is so positive.

 

[Gordon B. Clarke]

Hi guys,
I am up against it on a job and doing what I can to figure this out but looking for some help to confirm what I find. I am cutting a metric thread M50 X 2.0-6G and need to know the Pitch Diameter. I have Mic's for it but no gages. Is there an easy way to calculate this ? I do some Metrics but always find them in the book, this one is not where I usually get my information from and worry I'm going to screw up.

Thanks for any help

Ron

A few things that might help.

1. When you write M50 X 2.0-6G with a large G then that means it is an internal thread.

2. In metric external threads have small letters and internal large.

3. From the suggestions you are getting (and no objection from you) I'm going with the thread is M50 X 2.0-6g

4. The pitch diameter for that thread is:
max 48.663 and min 48.483

For internal min 48.701 and max 48.937 (M50 X 2.0-6H)

5. 6g and 6H in metric are standard just as 2A and 2B are in "American".

6. Here's a couple of links that'll maybe help you another time.

http://f-m-s.dk/2.03.pdf

http://f-m-s.dk/2.03 - inch version.pdf

http://f-m-s.dk/4.03.pdf

Probably shouldn't "spam" but measuring internal pitch diameter is easy. You'll have to email me to find out more. Click on my name.