Robotics Education & Competition Foundation
Online Challenges

Axle-Screw Adapter

3

DevinH
Entry ID #: 4479
Created: Wed, Jan 3, 2018 2:15 PM


Axle-Screw Adapter

Introduction

When building our lift, my team found that we had two options for joints: axles and screws. We found that there is no way to transition between axles and screws, which would have been very helpful for creating new joints. Also, there was no way to attach parts directly to the end of an axle without a large apparatus. We have always needed to resort to large mechanisms using gears and metal to attach parts to axles. Lastly, screw joints could not be attached to a motor, potentiometer, or optical shaft encoder because those parts were designed for axles. This axle-screw adapter would allow us to do all of this with a small and easy to use part!

Part Description

This part consists of a screw insert on one side and an axle insert on the other side. The screw insert extrudes inward 0.25 inches while the axle insert extrudes 0.75 inches. The screw insert has a hexagon front so a standard spanner can fit. Lastly, the axle insert side has two holes for a screw to allow the axle to stay in place or spin, depending on if the user puts the screw in. The two screws allow for a tight axle fit and are spaced apart in such a way so that one could screw metal parts tangent to the adapter with two points of connection.

Use in Designs

The axle-screw adapter can be used for hybrid joints. Rather than using only axles or screws for joints, this adapter would allow for a joint that utilizes both axles and screws. For instance, one could make a screw joint powered by a motor or connected to a sensor by transitioning from the axle to the screw.

This part can also be used as an attachment point. As stated in the introduction, one could attach parts to the end of an axle easily. This would reduce weight and streamline design.

The axle-screw adapter could also be used for structure. In many cases, it is difficult to get an exact distance between two points, which forces builders to use long standoffs along with spacers. Rather than using standoffs and spacers, a builder could use two axle-screw adapters and a specially cut axle.

Creating the Part

I modeled the part in Autodesk Inventor 2016. I first started off with the main cylindrical structure of the part. I kept the diameter consistent with a standard shaft collar so that the set screw can fit inside of it. I extruded it to 0.75 inches and put chamfers on the edges of the cylinder to remove any sharp, 90 degree edges. I then created a hole on the side of the cylinder for the shaft collar set screw. I had to create a plane tangent to the cylinder but parallel to one of the origin planes. Then I created two point which represented the centers of the circles. Next, I used the hole feature to drill the holes in the top. I then created the axle insert via a simple circular extrusion inward. I had to alter the previously created screw hole in order to make sure it reaches the axle insert. I then created the hexagonal extrusion on the other end of the cylinder then created a screw insert through it using the hole feature. Lastly, I put chamfers on the screw holes and rounded off the edge on the hexagonal extrusion to remove any more 90 degree edges for safety and ease of insert.

Conclusion

Through this project, I learned how much thought goes into part design and modeling. Designing a part is much more difficult than I expected because I had to think about size, weight, usefulness, safety, versatility, etc. I also learned how CAD is useful for designing parts. It is very easy to make a quick change to the design. If it was tested in real life, it would have taken more effort to change even a little thing. In the future, I will continue to use CAD to help design the robot and possibly to fabricate parts to be cut in polycarbonate for use on the robot. So far, Autodesk Inventor has allowed me to model the robot as it is built or before it is built. It has assisted my team and I with spacing, design decisions, and other build aspects. A fully modeled robot greatly sped up our construction process and eased design decisions. Learning CAD Software will help me become a better engineer in the future. This software and similar ones can help me in the future with design. Learning CAD also prepares me for advanced computer modeling and testing, which will be helpful for design during engineering. Overall, this project has been a great experience and has helped me learn more about computer modeling and part design.

Links / Videos

A short animation showing the part features and a possible way it could be used.