Skills: CNC Mill, Precision tolerancing, GD&T
In this first Design for Manufacturing (DFM) course project, my partner and I designed and machined a small treasure box intended to hold a single Milk-Bone for our dogs. The box features an internal pocket sized for the treat, along with an engraved Milk-Bone graphic on the lid.
Design Requirements/Constraints:
1. Stock Sizing 2x (3"x3"x1.25")
2. Parts must be held together with force/interference fit
3. Clearance fit to hold objects inside
4. Machining must be limited to tools available in the Olin College machine shop
A Tormach 770 CNC Mill was used to perform the machining operations:
1. Faced the stock to the right height using a 1Fl shear hog
2. Machined the pocket of the hole
3. Drilled both of the holes (different diams)
4. Reamed both holes to separate dimensions
5. Chamfered the holes and dogbone outline
We then tested the fit of the Milk-Bone and press-fit both the diamond and dowel locating pins to verify the alignment between the upper and lower halves of the box.
Above are the exact operations that were performed using the CNC Mill. These are all estimates and exclude any manual mill facing and other assembly processes.
Once the fit was confirmed, I used a manual mill to face the edges of the box, ensuring all sides were flush. I then masked the locating pins and pin holes before powder coating the part. After powder coating, we performed the final engraving on the outside of the box to clearly indicate its intended contents.
The table above shows estimated cost calculations comparing in-house machining versus outsourcing to evaluate the most cost-effective method.
