Hole Basis System In hole basis system hole limit dimensions are considered constant and various types of fits are obtained by suitably varying the limit dimensions of the shaft.

In a hole basis system the lower deviation for the hole 'H' is zero.

Depth of fusion (penetration) is the distance that fusion extends into the base metal or previous pass from the surface melted during welding.

The series of first 10 natural numbers is an arithmetic progressions with first tern as 1 and common difference 1.
So the sum of the series will be Sn = n/2 { 2a+ ( n-1 ) d } where n is the number of terms in the series, a is the first term and d is the common difference.
S10= 10/2 { 2(1) + ( 10-1 ) 1 }
= 5 ( 2+9)
= 5 ( 11 )
= 55

The operation of producing patterns on cylindrical external surface by pressing a tool is known as Knurling.