# Metric Fits (Tolerances)

Hello my friends, Today we are going to study metric fits.
Lets start.
We are using the fits during the machince parts design. This dimensional limits allow us to create working mutual parts.
the Tolerance Grades are divided by sixteen numerical accuracy.

Numbers from 1 to 4 we are using for the gages and the mechanical parts which desired to critical accuracy. This kind of dimensions are close to theorical dimension.
Grades from 5 to 16 using for more rough mechanical operations. For example turning, milling, sawing etc.
After lapping powder and oil add into the machine, plate starts running.
In the lapping powder involves some sort of abrasives. Such as Slisium carbide or diamond.
Lapping operation provide us the smooth surface and great surface roughness.
Pressure plate using is important during the lapping operation .
Parts are must not to touch each other. Because it couse edge deformation. It is better to use Sperator template.
Cold heading, pressing, roll forming etc. are taken place between twelve and sixteen
You may see the related operations with its grades. Those grades are determined for metal parts. Plastics are not involved in this list. But we can use coarse tolerances for plastic materials.
Capital letters uses for the internal dimensions for example hole, and lowercase letters uses for external dimensions for example, shafts.
First number determines the basic size, letter shows the deviation of the tolerance and the last number shows tolerance grade.
We can define the tolerances of work parts with its working condition.
Hole basis system
The desired clearances and interferences in the fit are achieved by combinations of various shaft tolerance zones with the hole tolerance zone "H". In this system of tolerances and fits, the lower deviation of the hole is always equal to zero.

Shaft basis system
The desired clearances and interferences in the fit are achieved by combinations of various hole tolerance zones with the shaft tolerance zone "h". In this system of tolerances and fits, the upper deviation of the hole is always equal to zero.

Clearance fit
It is a fit that always enables a clearance between the hole and shaft in the coupling. The lower limit size of the hole is greater or at least equal to the upper limit size of the shaft.
Transition fit
It is a fit where (depending on the actual sizes of the hole and shaft) both clearance and interference may occur in the coupling. Tolerance zones of the hole and shaft partly or completely interfere.

Interference fit
It is a fit always ensuring some interference between the hole and shaft in the coupling. The upper limit size of the hole is smaller or at least equal to the lower limit size of the shaft.

The option of the system for the specified type of product or production is always influenced by the following factors:

• Constructional design of the product and the method of assembly.
• Production procedure and costs for machining the part.
• Type of semi-product and consumption of material.
• Costs for purchase, maintenance and storage of gauges and production tools.
• Machine holding of the plant.
• Options in use of standardized parts.

you can see the various types of application. I want to show exaple A in solidworks. How the tolerances are giving

let see how we build basic assemly and I am going to blowing up to my assembly. Before blowing and draft operation, I will show the web sites which is going to help you for standart parts to download.

And I also show the how I give the tolerances in 3d.

Lets stard with exploding of the assembled part.
Give the tolerances according to sample A.
Give the motion to exploded parts.

We choose the standard tamplete and adjust the scale of the part. We have couple of option to scaling. Some of scaling ranges may attain or we can specify the special scale via teplate scale.
We can define the sheet format during drawing.

Dimensions can define easily with horizontal and vertically dimensioning.