Permalink Submitted by Macrocompassion on June 26, 2013
It is the friction force between the peg and the hole which causes it to offer resistance and to become a relatively tight fit.
The corners of the square will elastically deflect and create bearing stresses. Depending on the elasticity of these corners and that of the stiffer circular hole some friction force will make the fit a tight one.
However, in the case of the circular peg the bearing surfaces are determined by what is in effect a stiffer surface due to the non-pointed shape of the peg. Here the surface of the hole is flat offering greater stiffness too. This means less elastic deflection and greater forces. Consequently it is the round peg which is able to cause the tightest situation.
Permalink Submitted by Anonymous on March 10, 2016
You could have just as easily said more surface area touching equals more friction which equals a tighter fit.
The illustration depicts this very clearly.
Permalink Submitted by Anonymous on September 24, 2014
If we assume perfectly round and perfectly square elements, there are four points of contact in each case. Same tightness. The part of the peg that doesn't contact the hole is irrelevant.
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is it!?
Is it!?
It is!
It is!
Of pegs and holes
It is the friction force between the peg and the hole which causes it to offer resistance and to become a relatively tight fit.
The corners of the square will elastically deflect and create bearing stresses. Depending on the elasticity of these corners and that of the stiffer circular hole some friction force will make the fit a tight one.
However, in the case of the circular peg the bearing surfaces are determined by what is in effect a stiffer surface due to the non-pointed shape of the peg. Here the surface of the hole is flat offering greater stiffness too. This means less elastic deflection and greater forces. Consequently it is the round peg which is able to cause the tightest situation.
That's a creative answer
:-)
It's a no brainer!
You could have just as easily said more surface area touching equals more friction which equals a tighter fit.
The illustration depicts this very clearly.
pegs and holes
If we assume perfectly round and perfectly square elements, there are four points of contact in each case. Same tightness. The part of the peg that doesn't contact the hole is irrelevant.