shaft-hole coupling

[emix21]

hi, I would need help.I can't understand how,from the data of the problem I can go back to writing n8/k7 as indicated in the solution and text that I now bring you back.
I have no idea of the procedure I have to do to reach that conclusion, I know only that I have to look at the tables but I do not understand... if you can help me I am grateful, simply pointing out the steps to follow.http://imageshack.us/photo/my-images/192/esame1osett08.jpg/ solution solutionhttp://imageshack.us/photo/my-images/705/schermatab.png/ text

I think it's about the diameter of the hole, but I repeat I don't understand the steps.
Thank you.

 

[Exatem]

I had already partially answered here (read it):http://www.cad3d.it/forum1/showthread.php?p=233063#post233063and this happens when you ask the usual question in two or more different places...

Let us try to add (not to conclude) the speech.
We must first understand some definitions. with actual size, the resulting size is indicated by the processing. for this dimension, you have two limit dimensions within which you have to find the actual size. these are the maximum size and the minimum size (sufficiently intuitive).
the reference value of the size is defined and indicates the zero line to which the deviations are reported.
the deviation, since we have appointed it, is the algebraic difference between size, for example maximum, and the nominal size. so you will have two shocks, the superior which is the difference between the maximum dim and the nominal reference dim, and the lower than logically, is the algebra difference between minimum dim and nominal dim.

with tolerance is indicated the difference in absolute value between maximum and minimum dim i.e. that between upper and lower shock.
when mounting between two parts, you have a coupling that can be: with juvenile, uncertain or with interference. the Jew is the difference between the actual diameters of the hole and the tree when the hole is larger than the tree. interference is the difference between size when the shaft is larger than the hole. mating is defined uncertain when it can have jurocus or interference.

jumping some secondary definitions, you have two systems to define the couplings.
the base tree system, when it is maintained fixes the tolerance of the tree and varies that of the hole.
the base hole system when it keeps the hole tolerance fixed and the tree varies.
a whole range of tolerances quality is expected compared to the zero line whose quantity is indicated by a number while the tolerance position compared to the zero line is indicated with a capital letter for the holes, and tiny for the trees. therefore a full size is defined by the nominal value plus a symbol consisting of a letter and a number.
to use the tolerance system correctly, refer to tables available in any drawing manual.

 

[linch]

Well, in the meantime, the pairing that you requested is not what you described but n8/h7, which is completely different.
It is a question of uncertain mating.
that means that the tree seat can have interference, or mount freely on the hole.
I can't tell you anything else.

 

[emix21]

I'm sorry, I had to hurry now I read what you wrote and hope to understand.
Yes, I did wrong to write but I wanted to indicate that of the solution. As for the information I only have those to determine the type of coupling.
now I read
Thank you.

 

[emix21]

I got it. But I don't understand where to take the values to determine the type of coupling (from the data I have available)... from the diameter of the hole that design?
For example, if you have time, could you tell me the kind of reasoning that leads to say, in this case that mating is n8/h7?

 

[emix21]

"Restored" thisthread.. .no one can kindly tell me the kind of reasoning that must be done in order to obtain in this case the n8/h7 coupling.
the reasoning to follow
Thank you.

 

[Counterblow Hammer]

"Restored" thisthread.. .no one can kindly tell me the kind of reasoning that must be done in order to obtain in this case the n8/h7 coupling.
the reasoning to follow
Thank you.

Good say!

as nuns say: look... find!

your prof. at the end of the text wrote: "the p hole must accommodate with slight interference a pin: indicate the type of coupling"; take the old and dear expert manual, mating section and choose a coupling of the type "uncertain" assembled by hand or with light hammer strokes (on the table is called mazzuolo...): You will find that n8/h7 is the solution.

But be careful: under this choice there is the hypothesis that the pin has a fixed tolerance; this implies the use of abero-base couplings.

Understand? . . .

 

[emix21]

hi no...certainly I don't understand why you can't tell me the reasoning to follow, I kindly ask that if you don't want then I don't need anything.. thank you for the help but always say
the same things... I have untabella with only letters for
hole and base tree(young uncertain interference)
I don't have a table with all
possible combinations. I'd like to understand how
read the tavelles and
which are
for
to the numbers. .

 

[Fulvio Romano]

the "numbers" find them here.

 

[Ste_d]

What are you saying, what do you mean we don't want to help you?!? ! Just take a mating table as you were suggested and choose from those a pair with game/interference depending on what you want! next there is also a short description where it tells you for example "hot assembly with rounds of blue... assembly to the press...suitable for..." I mean it gives you a lot of information and you depending on the problem choose what it does to the case!
are divided into base tree and base hole, if the pin in this case must have a fixed tolerance you will have to look between those base tree. This means, in poor words, that the pin has a fixed size and the hole you want to match varies allowing you to have couplings with game/interference.

you had been linked to this very useful site where everything is explained, better than so you can! try to see what it says under n8/h7 http://www.tecnocentro.it/ita/accoppiamenti/selezione_accoppiamenti.htm

 

[Counterblow Hammer]

hi no...certainly I don't understand why you can't tell me the reasoning to follow, I kindly ask that if you don't want then I don't need anything.. thank you for the help but always say
the same things... I have untabella with only letters for
hole and base tree(young uncertain interference)
I don't have a table with all
possible combinations. I'd like to understand how
read the tavelles and
which are
for
to the numbers. .

It's like,
www.tecnocentro.it/ita/accoppiamenti/tolleranze.htmyou will find the mating selection section: Come on in.

in front of you will find the various recommended couplings divided between hole-base and base tree and in turn divide between blocks; uncertain and free.

Now the reasoning behind the solution is as follows: you must insert inside the hole p a pin with a minimum of interference; practical means that the coupling is uncertain (i.e. the max opposes a minimum of residence, but nothing compared to the blocks). at this point we see the law on couplings (i.e. the famous tables of the expert manual); first however it is necessary to decide whether to choose a hole-base type coupling (i.e. the hole always has h tolerance) or tree-base (i.e. the shaft always has h tolerance); personalment I choose the hole-base because it is much easier to make a hole with h tolerance than with any. made this choice just choose the coupling.

what the professor will not have told you is that the solution is not unique, but there are many depending on the criteria that a person adopts to choose the coupling.

for whatever they are available. . . .

 

[Ste_d]

Go here:
personalization I choose the hole-base because it is much easier to make a hole with h tolerance than with any. made this choice just choose the coupling.

what the professor will not have told you is that the solution is not uniqueBut there are many of them depending on the criteria a person adopts to choose the coupling.

for whatever they are available. . . .

and I add... Keep these aspects in mind:

 

[emix21]

thanks to all for the availability I will look as soon as possible.
I would like to point out that I never said he would not help me, but you are all very helpful, probably there was a misunderstanding between me and others about what I wanted, maybe I put the question wrong. .
Thank you.

 

[emix21]

hello thanks to the availability to all!I solved thanks again hello