Hardware used to attach parts to each other.
While being a seemingly insignificant factor, choice in metal material can have a drastic impact on a robot's performance. There are two types of metal used in VEX products:
Due to its lighter weight, aluminum should be used in subsystems that need to be kept as light as possible, such as lifts and game piece manipulators.
Steel is commonly used in areas where weight is less of a concern, or when a subsystem needs to be made heavier. In the event of a drive ratio favoring torque, a robot can be made heavier to help prevent being pushed by other robots.
As a general rule, however, aluminum should be used in the vast majority of places. Having a heavier robot, unless designed to be so, can be detrimental, and using aluminum instead of steel helps to drastically reduce the weight of a robot or subsystem.
Heavier Material
Lighter Material
More Rigid and Durable
Easier to Bend and Break
Appears Darker and more Reflective
Appears Lighter and flat
Important components for main structural foundations.
The most commonly used type of metal in VEX, C-Channels provide a stable, secure grounding for a majority of subsystems that can be used. The “C” shape contains two corners, which give the C-Channel a strong, sturdy form, making it ideal for structural use and bracing. There are three variations of C-Channel, in terms of their width:
This variety is the most used of the three, as the relatively small form factor makes it ideal for conserving space and weight.
A balance between the smaller 2-hole and larger 5-hole widths, the 3-hole width c-channels are great for saving space and weight, while giving slightly more room for mounting subsystems to the chassis.
The largest of the three widths, 5 hole width maximizes space for mounting, while taking up considerably more space and weight. Ideal for making your bot heavier, and less susceptible to defense as a result.
A variation of the C-Channel, the U-Channel has an extra hole on the bracket portion of the stock, giving it a more “U” shaped appearance. This stock is great for bracing different towers and other supports, as the “U” shape can envelope the towers, adding additional space for box-bolts, making the towers more secure.
Forming the shape of an “L,” these stocks of metal have either 1 or 2 holes on each end of the L, forming a 1x1 or 2x2 angle bar. Both are mainly used for support, rather than as a main piece of structure.
1x1 angle bars are mainly used for cross bracing, in the form of triangle or X bracing.
2x2 angle bars can be used to brace to parallel towers, while providing additional mounting space in the up or down direction.
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Smaller metal pieces used to mount structural components.
There are many different varieties of Gusset available to use in the VEX Robotics Competition, which can be broken down into two overall categories: Angle Gussets and Coupler Gussets.
The primary purpose of Angle Gussets is to mount main structural components at an angle to each other, with one notable example being the use of triangle bracing. Metal Angle Gussets are available in a variety of different sizes and angles from , in addition to custom-made gussets being used by many teams for angles unique to individual robots.
While there are a variety of different Angle Gussets available, they are all similar in that their purpose is to mount structural components at various angles and elevations.
Rather than mounting structural components at an angle, Coupler Gussets provide the ability to mount structure concurrent with existing components, continuing existing structures and extending the length of such pieces. Various Coupler Gussets can be found on .
The most popular variety of Coupler Gusset, C-Channel Coupler Gussets have a variety of different uses, with the main intended purpose being to connect two together and extend the total overall length of the metal.
Additionally, one common use for C-Channel Coupler Gussets is to reinforce existing structure. C-Channel Coupler Gussets are a convenient method to achieve , as slotting a C-Channel Coupler Gusset within a location in the structure of a robot can help increase the integrity of the structural component.
Though less popular than other available gussets, Angle Coupler Gussets are still an effective way to connect or reinforce structural components.
Rather than attaching or reinforcing from within the flanges, such as is the case with C-Channel Coupler Gussets, Angle Coupler Gussets mount to components from the outside faces. This makes Angle Gussets an effective way to "patch" weaker areas that are more vulnerable to , but due to the extra space taken up, are generally considered the weaker option compared to C-Channel Coupler Gussets.
Brackets are a relatively uncommon part used in the VEX Robotics Competition, marketed mostly towards containing various gearboxes that can be constructed using VRC-legal gears.
With their relatively large profile and strict purposes, the various different Brackets rarely see much use, in favor of custom components and use of more efficient mounting solutions. Brackets are more commonly used to cut into unique bracing and custom metal components, as they have a relatively large amount of material to work with. All brackets can be found on .
Versatile structural components with a variety of uses.
As barebones as it gets, Plate Metal is a 5x15 or 5x25 hole plate consisting of the standard square VEX bores every 0.5 inches (12.7mm).
Given the lack of flanges on either end of the plate, Plate Metal tends to be flexible along the longer flat face. As such, it is not advisable to use plate metal for any use-cases that require rigidity in that direction - Plate Metal is considerably stronger along the thin edge faces. One of the more common uses for Plate Metal is to cut and form it into custom-shaped pieces, rather than cutting to achieve the same result. Using Plate Metal for this functionality keeps the standard VEX bore spacing, as well as introducing more rigidity compared to VRC-legal plastics.
Similar to Plate Metal, Flat Bars are flat surfaces consisting of the standard VEX square bores, appearing in a 1x25 hole variety.
While not as apt for making custom pieces as Plate Metal, Flat Bars are still effective as a source of mounting parts that require little rigidity over longer distances. Use-cases that require stronger connections, such as bracing important subsystems on a robot, should be left to stronger components such as C-Channels or Standoffs.
Flat Bars can be found at vexrobotics.com.
Simplify robot construction with hex nut retainers and standoffs retainers.
Retainers are nylon, hexagonally-shaped parts which have varying protrusions depending on the type of retainer used. There are two overarching types of retainers: hex nut retainers and standoff retainers. Hex nut retainers all feature 11/32" wide hexagonal bores that are meant to keep 11/32" wide 8-32 nuts of any type captive. Similarly, standoff retainers can keep any hexagonal fastener that is 1/4" wide (such as a standoff, narrow hex nut, or 4-40 nut) captive in its hexagonal bore. The resulting captivity of these fasteners allows the user to forgo using a crescent wrench altogether, as a screw can easily thread into the nut or standoff without any way for that fastener to rotate.
There are three types of retainers sold by VEX Robotics which come in both hex nut and standoff retaining forms.
The most versatile of the three, the 1-post retainer simply keeps a nut or standoff captive for a screw to then thread into it. Like the name suggests, it has a single nylon post protruding out from it with a square peg that can extend through two surfaces of VEX aluminum, such as two . This square peg is around the same size as common VEX square holes, allowing it to fit snugly into the hole.
Although less commonly used, the 4-post retainer can be a massive time-saver when developing perpendicular structure. Unlike the 1-post retainer, this retainer has four square pegs that surround a captive nut or standoff. Since the four square pegs also extend through two surfaces of aluminum, it completely eliminates any chance for play between two surfaces while only requiring one screw and one nut or standoff. However, because of the geometry of the retainer, it relies on the metal having diagonal holes, meaning it can only be used with two-hole wide C-channels, two-hole wide , and U-channels, but not with three-hole wide C-channels, five-hole wide C-channels or one-hole wide angles.
Ever helpful with motion components, the 1-post retainer with bearing flat can be a handy replacement for where space allows. The primary purpose of this retainer is to reduce friction where shaft are being used by using encapsulating a shaft with a nylon hole rather than having it contact the square hole of a C-channel. Other than its function as a bearing flat, the retainer otherwise acts the same as the 1-post retainer, and still has a square peg with the same dimensions on the opposite side of the bearing flat hole.
Both hex nut retainers and standoff retainers alike have significant use cases thanks to their fastener captivity ability. Generally, these retainers can serve as a gateway to saving weight on a robot because they make previously obscure fasteners more viable by allowing them to stay captive. For this reason, nuts that would struggle to stay threaded onto a screw when faced with vibration, such as a basic steel hex nut, could be used liberally with the help of a retainer. Some helpful use cases for using a retainer could include:
Attaching a hex nut/standoff retainer with bearing flat on a rotating mechanism to reduce friction while saving weight.
Unlike a normal bearing flat, which requires two screws and two nuts to attach to a robot, a retainer with bearing flat only needs one screw and one nut.
Since a retainer with bearing flat is mounted off-center (the bearing hole is on the side), attention to detail is required to ensure that the retainer properly aligns itself and is flush with the metal.
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Ensure smooth, frictionless motion in moving parts.
The most frequently used type of bearing among competition teams, Bearing Flats are most often used on joints to ensure the axle spins smoothly without jamming against a flat face.
Comprised of three unthreaded bores along a plastic face, Bearing Flats are most commonly secured to C-Channels or other structural components through the outer two bores, so as to distribute pressure on the bearing evenly across both sides. With standard VEX axles and screws fitting perfectly through the center bore, this reduces friction in the axle by providing a smooth, consistent inner surface for free rotation.
Bearing Flats can be found on .
While not quite as commonly used as Bearing Flats, Pillow Block Bearings achieve a similar function for a different use-case.
While standard Bearing Flats are mounted the the main structural component parallel to the axle of the rotation, Pillow Block Bearings are mounted in a perpendicular fashion. For example, Pillow Block Bearings would be mounted on the top of bottom of a c-channel flange, whereas a standard Bearing Flat would be mounted within the two flanges. Using a Pillow Block Bearing can help either raise or lower the main chassis structure from the ground, either raising or lowering overall ground clearance.
Pillow Block Bearings can be found on .
Both Bearing Flats and Pillow Block Bearings are available in high-strength varieties. These high-strength bearings have a much larger center bore, in order to accommodate high-strength axles.
The high-strength Bearing Flats and Pillow Block Bearings do not differ in overall functionality from their standard variants, the only difference is their ability to accommodate a larger axle. These parts can be useful for high-stress environments when designing a robot, such as in high-torque gear ratios.
High-Strength Varieties of Bearing Flats and Pillow Block Bearings can be found on .
Ball Bearings are an incredibly versatile option for ensuring low-friction under stress in moving parts.
While taking up more space than a standard Bearing Flat, Ball Bearings do offer unique advantages, such as consistently low friction under heavy load. Because of this, Ball Bearings are incredibly useful for high-speed mechanisms such as Flywheels, where having consistent rotation and low friction are essential.
Ball Bearings can be found on .
Utilizing 1-post hex nut retainers to make the following fasteners impervious to vibrations and therefore viable:
Steel 8-32 hex nut
Nylon 8-32 hex nut
Aluminum 8-32 hex nut
Utilizing 1-post standoff retainers to make the following fasteners impervious to vibrations and therefore viable:
Narrow 8-32 hex nut
4-40 hex nut
Using a 1-post hex nut/standoff retainer's protruding square peg to eliminate slop between two pieces of metal while also potentially saving weight in the process.
Rather than using two shoulder screws to fasten the two surfaces together, only one is needed since the retainer's square peg will inherently eliminate slop.
Using a 4-post hex nut retainer to save weight (by only requiring one pair of fasteners instead of two) and eliminate slop at an attachment point of two perpendicular C-channels.
This should only be done in low-stress situations. If done in a scenario where the perpendicular C-channels are likely to become deformed, the structural integrity of the 4-post hex nut retainer is ambiguous.
Crucial for attaching structural pieces to each other.
In the scope of the VEX Robotics Competition, the typical screw will be steel and will have an #8-32 thread size and can have a length anywhere from 0.25 inches to 2.5 inches. However, in VEXU, limits on the thread size, material, and length are lifted.
Of more importance to the user of a screw is the drive style and its specialty features.
Star Drive, otherwise known by its trade name as "Torx" Drive, is the most common drive style in VEX. It offers the advantage of being generally more resistant to stripping than its hexagonal predecessor, but has the tradeoff of being difficult to purchase at a hardware store. Convenient sources of these types of screws include the , , and .
Hex Drive was widely used in previous seasons of VRC, but has since been mostly eclipsed by Star Drive screws. Hex Drive is now largely unpopular due to the fact that it is notorious for stripping easily. Additionally, similar to the Star Drive style, it is difficult to find commercially. Potential sources of these types of screws include the and .
Phillips Head screws are not screws that are commonly associated with VEX Robotics, but they can be utilized conveniently due to the fact that they are incredibly easy to purchase. Normally, most hardware stores will sell their #8-32 screws with a Phillips Head style. Additionally, those hardware stores will almost certainly sell tools that are compatible with these screws. You can purchase these screws at a hardware store such as Ace Hardware, Lowes or Home Depot.
Most screws will be normal screws that have no additional benefit. However, there are three particular types of screws that can perform special tasks.
Shoulder screws are screws which are not threaded near the head. Usually, this lack of thread, referred to as the "shoulder", has a length that spans no more than 1/8 of an inch. The benefit of using a shoulder screw is that the shoulder is larger than the diameter of the threading. This means that, when passed through the hole of a C-channel or angle, the screw will always be nearly perfectly centered in the hole. This is excellent for any structural purpose, and should especially be utilized when constructing drivetrains to ensure that the drivetrain is "square" and aligned properly. Shoulder screws can be purchased in the Hex Drive variant from the or in the Star Drive variant from .
Locking screws are normal #8-32 screws that have thread locker brushed onto the ends of the screw's threading. They bring the added benefit of making the screw resistant to vibration, meaning that the screw cannot loosen unless a screwdriver interacts with it. They can be purchased from the with thread locker already brushed onto them, or they can be made by brushing any commercial thread locker, such as Loctite, onto an #8-32 screw.
While not particularly useful, VEX's thumbscrews offer a simplistic way to tighten screws. The method of tightening these screws is as the name suggests: they can be tightened by hand using the knurled head. One benefit that competitors have found within the thumbscrew is the fact that it is made of plastic compared to the typical stainless steel. This would make it a lightweight alternative to using any other screw. They can only be purchased from the .
These nuts are the least used in VRC, as they have no teeth to keep them tight without heavy maintenance, nor rubber to maintain their position on the screw.
The most common type of nut used in VEX, these nuts have teeth on the inner portion of the nut (the end that contacts the attached surface), which keeps the nut solidly in place without much maintenance.
Able to be used most everywhere without problems.
Nylock Nuts, or Nylocks, these nuts have a rubber ring on the top portion of the nut (that faces away from the attached surface), which keeps it in place on the screw. Able to be used in the same places as Keps Nuts, but generally should not be, as Keps Nuts are easier and more efficient to use.
Most commonly used in Screw Joints, as it is not advisable to tighten the outer nut on a screw joint all the way (this would stop whatever is on the joint from moving). Using a Nylock for this purpose allows the nut to retain its place on the screw, without needing to be tightened as far as it can go.
Standoffs are a fairly common part with a wide variety of use-cases in the VEX Robotics Competition.
Comprised of a long, threaded interior formed into a hexagonal shape, standoffs are often used to space pieces of structure over long dimensions, as screws can be threaded into either end of the cylinder. Due to their versatile dimensions, standoffs are often used in bracing components of a robot, and are sometimes used as main structural components themselves.
In the VEX Robotics Competition rules, there is a maximum length of 2.5 inches (63.5mm) for any commercially available standoff. Common sources of standoffs include the , , and .
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