wiki:Mechanical/Mechanical/Overview/Fasteners

Bolts

https://4.imimg.com/data4/RF/XQ/MY-26034901/iron-bolt-250x250.jpg This is a bolt. They are the most common fasteners we use on robotics. The difference between a bolt and a screw is that a screw goes into a hole that already has internal threading (or the screw digs its own threads into a softer material) Whereas a bolt fastens things by sandwiching them with a nut. The bolt shown has a hex-head, which means the head of the bolt is in the shape of a hexagon; heads come in many shapes and styles. Bolts are measured by diameter and thread count. Diameter is measured either in inches or millimeters, and thread is measured by threads per inch. The most common bolts we use on this team are 1/4 20 (one quarter inch diameter, twenty threads per inch).


There are many designs for the heads of screws and bolts. The oldest designs used a simple slot called a flat-head; these are common, but it's easy for a driver to slip out of the slot and for the slot to get damaged. An improved design used a cross called a phillips-head which makes it much easier to keep a screwdriver in the head when tightening or loosening. Further improvements included hex, hex socket, torx, and many more. See some examples below and their matching drivers.

http://www.homedepot.com/catalog/productImages/1000/9c/9c5e4fca-c5eb-4de5-a437-75bc182e0757_1000.jpg flat https://images-na.ssl-images-amazon.com/images/I/41-PJ7nDSvL._SX342_.jpg phillips https://4.imimg.com/data4/RF/XQ/MY-26034901/iron-bolt-250x250.jpg hex http://www.okmetal.com.tr/images/resim/7650_5758404102011165656.jpg hex socket https://www.belmetric.com/images/MSPX8X30%20Stainless%20Torx%20Pan%20Cheese%20Screw.jpg torx
http://c.shld.net/rpx/i/s/i/spin/image/spin_prod_1159448512 Flat & Phillips Drivers http://c.shld.net/rpx/i/s/i/spin/10042699/prod_17582145712 Hex/Nut Driver http://www.roadcyclinguk.com/news/images/Lifeline-Allen-Keys-hi.jpg Hex/Allen Key(for hex socket)



Nuts

https://images-na.ssl-images-amazon.com/images/I/21eW69Bl1KL.jpg

This is a nut. The purpose of a nut is to screw onto a bolt to use as a fastener. However, regular nuts can sometimes loosen or fall off. On the team we often use lock nuts, which have nylon on the inside to grip the bolt and ensure it does not come undone. The other options are a different type of lock nut, which grabs material using little teeth, or Locktite, which is essentially glue you can drip on a nut/bolt combo to ensure it won't come undone. For a nut to fit on a bolt, it must have the same diameter and the same thread count. Therefore, only a 1/4 20 nut will fit on a 1/4 20 bolt. To tighten a nut onto bolt, a nut driver or a wrench is generally used.



Screws

https://i.pinimg.com/originals/e1/d2/57/e1d2574c6972561bdb11f242d9f80760.png This is a screw. As was mentioned before, the difference between a screw and a bolt is that a screw uses the threads to grasp onto a material instead of using a nut. The head of the screw will generally be one of four types. The type of head determines what sort of tool is used to tighten the screw. The most common type of head is phillips head, which is inthe shape of a cross. To tighten this screw, a phillips head screwdriver must be used. The second most common type of screw is a flathead screw. To tighten a flathead screw, a flathead screwdriver must be used. The other two semi-common types of screws are allen wrench screws, which must be tightened by an allen wrench, and torx head screws, which must be tightened using a torx head screwdriver. Screws are rarely used in metal, but we often use them in wood to construct prototypes or field pieces.



Rivets

http://img.directindustry.com/images_di/photo-g/16008-10697548.jpg

Another type of fastener is called a rivet. Rivets can be made out of metal and plastic, and they tend to be more temporary than bolts or screws. They are especially used in prototyping when constructing a basic cardboard prototype. A rivet has two pieces, and to fasten something together, one side is clicked into the other and locks in place. There are many different types of rivets, and they work in many different ways.



Helicoils

https://www.youtube.com/watch?time_continue=1035&v=T3I6RRHK9dE&feature=emb_logo


Adhesives

https://dingo.care2.com/pictures/greenliving/1241/1240539.large.jpg

Adhesives are things that are used to attach things via stickiness. An obvious adhesive is duct tape (or any tape), and duct tape is commonly used to help prototyping and to fix small problems on the robot. Another type of adhesive is glue. On the team we will occasionally use super glue and gorilla wood glue, but we mostly use 2-part epoxy which is extremely strong once it has cured. Epoxy comes as two thick liquids that harden once they are mixed together and given time to cure (harden).


Last modified 5 months ago Last modified on Dec 15, 2020, 11:04:17 AM