Machinist Apprentice | More Deburring and Cleaning | Day 25

Today was more deburring, cleaning, and prepping parts for shipment. My boss did the final piece, which is a unique shape requiring three operations to mill it all out and didn't have enough time before it's due to have me do it. 

Removing copper burs is the bane of my existence; this specific piece has over 30 edges on it and ten parts total. Not to mention, copper is very resilient to any sort of tool you throw at it and takes several passes to clean up each edge. If you're not already aware of what a burr is, it's typically melted or pushed away material that the cutter (in this case endmill) didn't slice but simply shoved it to the side. I'll put up an example I found online of a more exaggerated version (before and after).

Part of the design included a section with three thin flat walls that were extended out and open on one end. If you tried machining it without any modifications, you would have a lot of trouble getting an excellent finish and staying in tolerance due to the fragility of the wings. The way he overcame this was to make a temporary wall on the opposite end and fill the pocket with a hard plastic molding material, then you can come in later and remove the partition with better rigidity and structure without the worry of the walls buckling in. The casting material is a Quik-Cast Polyurethane two-part resin and takes only an hour to cure with low shrinkage.