Lift Cart
A side photo of the custom forklift before making changes.
At Desktop Metal I had to solve an interference issue with a custom forklift. This was my first major engineering challenge outside of school. I used beam deflection and bolt calculations to validate my design changes with analyses. With these analyses, I was able to verify that the structural safety factors were above two. Furthermore, I was able to back up my work during a design review in front of senior engineers. Plus after the design review, I developed my GD&T skills with technical drawings of parts.
First Time Using GD&T!
My first part had to lengthen the arms of the forklift without changing the existing parts. So, I designed a simple extension block out of aluminum. This was my first time practicing GD&T and applying technical drawing standards.
My first technical drawing of a part I designed using GD&T drawing standards.
My technical drawing of a foot extension, done with manufacturability in mind.
We Need More GD&T!
I then designed an extension for the forklift’s feet and created another technical drawing. My part’s drawing included more GD&T standards such as perpendicularity, true position, and datums. Furthermore, I designed with manufacturability in mind. So, I placed reference dimensions to make machining and inspection easy. I also analyzed tolerance placement to guarantee the part would fit with other components.
What Does the Simulation Say?
Top left, a simulation of the forklift’s arm under the weight of the payload. Right side, a simulation of my extension blocks under load. Bottom left, a simulation of an eyebolt for added support.
To support my designs, I did hand calculations of a cantilever beam to find the shear force, bending moment, and maximum deflection of the forklift arms under a load. To cross-check my hand calculations, I did a SolidWorks FEA analysis of the forklift’s parts and assemblies. Not only were my calculations valid, but the analyses improved my simulation skills and uncovered points of stress concentration.
Left side, both machined extenders one of which has the threaded bumper and spring pin. Top right, one of the extenders onboard the forklift. Bottom right, one of the extenders without hardware.