Special Screwdrivers and their Uses - ITI Online Note

 Standard and Special Screwdrivers and their Uses 

1- Screwdrivers are used to tighten or loosen screws which are fixed in the machine element . 

Classification of Screwdrivers 

1- Standard type Screwdrivers with tips to suit recessed head screw slots . 

2- Special type Screwdrivers with tips to suit recessed head screws . 

Features of standard screwdrivers 

1- Screwdrivers must have : 

i- Tips to turn screws with slotted heads.

ii- Handles of metals , wood or molded insulating material , shaped to give a good grip for turning .

Parts of screwdrivers

iii- Blades of hardened and tempered carbon steel or alloy steel . 

iv- Round or square blade with length ranging from 40 mm to more than 350 mm. 

v- Flared tips which vary in length and thickness with the length of the blade . 

Standard Screwdrivers 

1- Standard screwdrivers are classified as 

i - Heavy duty screwdrivers . 

ii- Light duty screwdrivers .

iii- Stumpy screwdrivers . 

Heavy duty screwdrivers

1- This screwdriver has a square blade for applying extra twisting force with the end of the spanner . 

2- Heavy duty screwdrivers of London pattern have a flat blade and are mostly used by carpenters . 

Heavy duty screwdrivers

Light duty screwdrivers

1- This screwdriver has a round blade with parallel tips . 

2- This screwdriver is used by electricians.

3- The blades are sheathed in insulation to avoid short - circuiting live parts . 

Light duty screwdrivers

Stumpy screwdrivers 

1- These are small sturdy screwdrivers . 

2- They are used when other types of screwdrivers cannot be used due to the space limitations.

Stumpy screwdrivers

Offset Screw Driver

1- Offset screwdrivers are used on screws which cannot be reached from above . 

2- They are made with short blades and with the tips at right angle . 

3- Greater turning force can be applied on screws by these screwdrivers because of their leverage . 

Offset Screw Driver

Ratchet Screwdrivers 

1- These screwdrivers are made with a three - position ratchet control for screwing unscrewing of a screw and also providing a neutral position.

2- They are used for turning screws in confined spaces . 

3- They can be operated without changing the hand grip . 

4- They are used for slackening or tightening with a medium force .

Ratchet Screwdrivers

Phillips ( cross - recess ) screwdrivers 

1- Phillips screwdrivers have cruciform or cross - shaped tips that are unlikely to slip from the cruciform slots in Phillips recessed head screws .

Phillips ( cross - recess ) screwdrivers

2- The end of the four flats is tapered to an angle of 53°

3- The extreme end is ground to 110° . 

4- Four different sizes to cover the full range of screws are available . 

5- These are specified by point sizes 1 , 2 , 3 & 4 which correspond to the size of the Phillips screw heads.


Comments

Post a Comment

Popular posts from this blog

Mechanical Use of SCRAPER Tool- ITI Online Note

Image
What is Scraper Tool Use 1- It is a specific type of operation of removing convex spots from the machined surface and the tool used for removing complex spot is called scraper .  2- For obtaining a fine surface finish,  3- It is a very important hand. Operation employed.  4- Depending upon the specific work to be performed, scrapers vary in size and shape. 5- Scrapers are usually made out from warmouth or used old files that can't be used for further filing work.  6- For manufacturing scrapers , the files are heated to forging temperature and forged to the required shape.   7- Then further hardening and tempering operations are performed on files to get the desired hardness.  8- The cutting edge of the scraper is ground to sharpen it for removing the material.  9- The toolmaker's scraper is knurled at one end while the other end has the cutting edge. Types and uses of scraper  1- Flat scraper . 2- Hook scraper. 3- Half round scraper . 4- Circular scraper . Flat scraper 1-
Read more

What is Power Tool's? ITI Online Note

Image
 What is Power Tool's   1- A power tool is a tool actuated by power source and mechanism other than manual labor used with hand tools for fastening bolts and nuts .  Power wrench  1- A power wrench is type of wrench that is powered by other means than human force.   2- A typical power source is compressed air .   3- There are two main types of power wrenches :  i- Impact Wrenches and  ii- Air ratchet or pneumatic ratchet wrenches. Pneumatic torque wrench  1- A pneumatic torque wrench is a primary torque multiplier or a gear box that is mated to a pneumatic air motor. 2- At the end of the gear box is a reaction device that is used to absorb the torque and allows the tool operator to use it with very little effort .  2- The torque output is adjusted by controlling the air pressure .  3- These planetary torque multiplier gearboxes have multiplication ratios up to 125 : 1 and are primarily used anywhere accurate torque is required on a nut and bolt , or where a stubborn nut ne
Read more

Oxy acetylene GAS WELDING and Techniques - ITI Online Note

Image
Oxygen acetylene Gas Welding torch or blow pipe are used  1- Oxygen and acetylene gas pressure is reduced by gas regulator.  2- These gases are supplied through suitable hose to welding torch.  3- Gases are mixed in mixing chamber of welding torch and supplied to welding tip or nozzle.  4- The gas mixture is burnt to produce a flame to carryout welding operation.  5- There are two types of Gas welding torches,        • Low pressure or injector type        • High pressure or equal pressure type. 6- Low pressure torches are used with acetylene pressure obtained from acetylene generator at a pressure of 0.02 bar (less than 1 psi).  7- High pressure torches are used with acetylene stored in cylinder at a pressure of 8 bar. Low pressure or injector type torch  1- It is operated by low pressure acetylene at 0.02 bar.  2- As acetylene is at low pressure, it is necessary to use oxygen at high pressure (approximately 2.8 bar). 3- Oxygen enters into mixing chamber through passage locate
Read more