Image I found online showing drawing of a fully assembled Atlantic Engine from the Lunenburg Foundry
Almost completed connecting rod
Image from online of an Atlantic Engine, which is what our completed engine will look like.
CONNECTING ROD: LUNENBURG ATLANTIC ENGINE
For my second year in the Pappalardo Apprentice Program, the seven seniors worked together to make all of the parts to recreate an Lunenburg Atlantic Engine, colloquially known as the "Make and Break" Engine. We actually worked closely with the Lunenburg Foundry in Nova Scotia that originally designed and made the Atlantic Engine we were recreating.
I worked to fabricate the connecting rod, the part that transfers motion from the piston to the crankshaft. It was the only bronze part the apprentices made, as all of the other components were cast iron. We had to fully fabricate our parts ourselves, starting with creating CAD drawings for the parts based on the drawings we got from the Lunenburg Foundry. After making the CAD for the part in Solidworks, modifications need to be made to the CAD so that the part could be sand cast. These changes included filling in holes and undercuts with solid material, adding drafts, and accounting for shrinkage. After completing the CAD, I created a program to CNC machine the connecting rod (split into pieces) out of green foam to create molds for sand casting. Once the foam molds were fabricated, I packed a flask to sand cast the part and worked with MIT's foundry to actually perform the casting. Pictures of this whole process are below.
After a successful first pour, I began working to machine the cast part based on the original drawings. The connecting rod required many machining operations, which taught me about the difficulties of machining cast parts and particularly taught me a ton about fixturing. By the end of the semester, I did not have enough time to completely finish machining the part, but it was very close to being done (main operation left was just boring and babitting the large hole). A junior apprentice along with the shop staff are finishing up the parts that the seniors didn't complete, so the engine should be completed by sometime in early 2020. Once the engine is complete, images will be added to this page of my completed connecting rod along with the whole engine.
Machined green foam sand casting molds
On the right is one of the packed flasks, ready to pack the second half of the flask.
Second half of the flask ready to be packed with sand
Carving gates and runners out of the sand after separating the two flasks
Opening the flask a few hours after the pour - looks like a success!
Part taken out immediately after opening the flask, a lot of material to remove.
Parts after excess metal was cut off. Still a lot of material to remove, but much will be removed through machining process.
During the multi-week process of machining the connecting rod.
Took this image once I got far enough in the machining process to be able to connect the two pieces together
Sometimes the fixturing was not so elegant