Have you ever seen a clutch this burned?

[ribbert]

Size for size a fine thread is stronger than a coarse thread . This is both in tension (because of the larger stress area) and shear (because of their larger minor diameter). 2. Fine threads have also less tendency to loosen since the thread incline is smaller and hence so is the off torque.

Then why is a coarse thread the default unless a particular application calls for a fine thread? 

Noel

[Pat Conlon]

Ok, so you concede that fine threads are stronger?

The answer to your current question is in the links I provided you.

I know it, but it's better if you find it on your own.

[Earl Svorks]

  Pat,
I paraphrase Noel and ask, have you ever ,even once seen an aluminum casting or forged piece that
came from a factory that had a hole tapped with fine threads?
      Cheers
     Simon

[Earl Svorks]

   Here, I quote from one of the links Pat was kind enough to provide.


"In relatively low strength materials such as cast iron, aluminum, magnesium, brass, bronze, and plastic, coarse threads provide more resistance to stripping than fine or extra fine threads."

   This is what I was alluding to in the matter of thread strength.
    Cheers and goodnight. up early tomorrow for chiropractor. A little more "Spinal Decompression" therapy.
   Off work for a full year with back problems, but I'm starting to feel better .
   Simon
   

[ribbert]

   Noel,
  The inserts pictured in your post appear to have a finer pitch on the outside (1.25 mm maybe) and perhaps 1.5 mm on the inside. This fits with what you said about the VW mod. Do my eyes deceive me,
or are these the same?
   
   Cheers
   Simon

Simon, I re posted the picture Pat used several posts earlier, it was just indicative of what I was referring to. Pat might know what they are as he found the photo.

Noel

[Pat Conlon]

Yes, of course, course threads are less prone to stripping and cross threading and promote faster assembly....sure.

That's a different matter than saying that course threads have higher tension values or shear values than fine threads.

Math is math and numbers don't lie.

[TexasDave]

Yes, of course, course threads are less prone to stripping and cross threading and promote faster assembly....sure.

That's a different matter than saying that course threads have higher tension values or shear values than fine threads.

Math is math and numbers don't lie.

We are arguing apples and oranges. There are different threads for different applications in harder and softer materials.The fact that you can buy both coarse and fine threads ought to tell you that neither is "best" for every single application. They each have advantages and disadvantages, mostly depending what is being threaded onto the end.

Fine threads are definitely stronger and give a higher clamping force for a given tightening torque. They are also less likely to come loose. Fine pitch threads are always the best choice where a nut is to be used.

Coarse threads are better when a blind hole is tapped into soft material. You will always find coarse threads going into aluminum castings, because fine threads would tear out of soft material much more easily.

The problem is not the bolt itself, but the strength of the material the bolt goes into. So we need both coarse and fine bolts depending on what screws on the end.

Dave

[Pat Conlon]

Yep, I agree.

[Earl Svorks]

  Well said Dave,and I also agree.
Ever notice how rare it is for two mechanics to agree on just about anything ? During the years that I worked in the capacity of a Provincial Vehicle Inspector in the CVIP program,I needed to be aware of the details of the vehicle act as it applies to cars , trucks,motorcycles etc.The operation and requirements of them and their operators  This led to my having to purchase copies of "The Vehicle Act" from the Queens Printer in Victoria. This
came with annual update sheets so it was always current. I read all of those legal tomes front to back more than once. In the end,and to my surprise and disappointment ,  most of it was by no means straight forward nor clearcut in black and white. In fact it left me thinking that really all of it appeared to have been composed and written by lawyers, for lawyers. Most of it's content open to interpretation, or argument.
  Good for lawyers , not so good for safety inspectors or angry taxi owners.
Always remember what the judge will tell ya',, "ignorance of the law is no excuse"
   Cheers
  Simon
   VIP#MO*&20

[ribbert]

 
......Ever notice how rare it is for two mechanics to agree on just about anything ?
  Simon
   VIP#MO*&20

Sorry Simon, but that's not true.

Noel

[TexasDave]

 
......Ever notice how rare it is for two mechanics to agree on just about anything ?
 Simon
  VIP#MO*&20

Sorry Simon, but that's not true.

Noel

OK Noel we agree on something. But ever notice how rare it is for two motorcycle riders to agree on anything mechanical ?   

Dave

[ribbert]

I know it.........

I can see that from the your post, you explain it well.

Noel

[Pat Conlon]

Then why is a coarse thread the default unless a particular application calls for a fine thread? 

Noel

For the reasons I posted in the links....

Read them, then you tell me....