You hear it all the time. "This or that 1911 is unreliable because it's manufactured to tighter tolerances than the original design." "AKs are more reliable but less accurate than AR-15s because of looser tolerances". Ad nauseam.
To a person who knows the difference, it just as annoying as hearing someone say “clip” when they mean “magazine”. I can understand why there might be some confusion, as tolerance and fit often go hand-in-hand, but they are NOT synonymous.
Put simply, “tolerance” is an engineering and manufacturing term that refers to the amount that a part can deviate from the design specifications and still be considered “good” or “acceptable”. A margin of error if you will. Any part that falls outside of this margin should be rejected as it is out of spec. Quality Control 101.
A “tight” tolerance means that this margin of error is very small, which increases the number of rejects and decreases the number of accepted parts and/or necessitates the procurement and use of more sophisticated machining equipment and techniques. This drives the total manufacturing cost up but results in a more consistent product.
A “loose" tolerance is the exact opposite. Fewer rejects and more accepted parts make for lower material/manufacturing costs but with greater inconsistencies in the product. Whether those inconsistencies negatively impact reliability is dependent on how great the inconsistencies are and the intended fit of the original design.
“Fit” of course refers to the clearance between different parts in a given system. It can be tight, loose, or whatever.
Here’s where the confusion usually comes in.
A design with a tight fit always requires tighter tolerances to work properly while a design with loose fit allows for looser tolerances.
A loose fitting design that is manufactured to tight tolerances will still be loose fitting, it’s just that each part will be closer in specifications to the original design. They will be loose in a consistent way. A tight fitting design made to loose (rather, insufficiently tight) tolerances might fit fine, or it might fit too loosely or too tightly.
In essence, a gun that doesn’t function reliably because it’s too tight fitting isn’t unreliable because of tight tolerances. Quite the opposite. It’s unreliable because the tolerances aren’t tight enough.
Tighter tolerances will NEVER negatively impact the reliability of a mechanically sound design. Only tolerances which are TOO LOOSE will.
/rant
To a person who knows the difference, it just as annoying as hearing someone say “clip” when they mean “magazine”. I can understand why there might be some confusion, as tolerance and fit often go hand-in-hand, but they are NOT synonymous.
Put simply, “tolerance” is an engineering and manufacturing term that refers to the amount that a part can deviate from the design specifications and still be considered “good” or “acceptable”. A margin of error if you will. Any part that falls outside of this margin should be rejected as it is out of spec. Quality Control 101.
A “tight” tolerance means that this margin of error is very small, which increases the number of rejects and decreases the number of accepted parts and/or necessitates the procurement and use of more sophisticated machining equipment and techniques. This drives the total manufacturing cost up but results in a more consistent product.
A “loose" tolerance is the exact opposite. Fewer rejects and more accepted parts make for lower material/manufacturing costs but with greater inconsistencies in the product. Whether those inconsistencies negatively impact reliability is dependent on how great the inconsistencies are and the intended fit of the original design.
“Fit” of course refers to the clearance between different parts in a given system. It can be tight, loose, or whatever.
Here’s where the confusion usually comes in.
A design with a tight fit always requires tighter tolerances to work properly while a design with loose fit allows for looser tolerances.
A loose fitting design that is manufactured to tight tolerances will still be loose fitting, it’s just that each part will be closer in specifications to the original design. They will be loose in a consistent way. A tight fitting design made to loose (rather, insufficiently tight) tolerances might fit fine, or it might fit too loosely or too tightly.
In essence, a gun that doesn’t function reliably because it’s too tight fitting isn’t unreliable because of tight tolerances. Quite the opposite. It’s unreliable because the tolerances aren’t tight enough.
Tighter tolerances will NEVER negatively impact the reliability of a mechanically sound design. Only tolerances which are TOO LOOSE will.
/rant
