My shop time this past summer was spent modeling a Ford 289 Hi-Po engine. Its five main castings include the block, a pair of heads, the intake manifold, and a timing cover. Using workshop manuals and online photos for reference, I set out to build a 1/3 scale model of the popular 60's era muscle car engine.
A precise assembly of these five complex parts is a must, but the sources I was using left me with plenty of blanks to fill in. After a frustrating month of endless design and re-design, George Britnell graciously offered me his SolidWorks models of a nearly identical full-size 302 engine. He used these in another thread on this forum to 3-d print a quarter scale version of the same engine. It's fair to say that without his help my own project would have died on the vine.
SolidWorks has a powerful tool that's capable of scaling an entire finished model, and this is just what's required for 3-d printing. George's printer resolution allowed him to retain the rich detail in the engine's original castings, and he was able to print a museum quality model. Trying to replicate his results in metal on my Tormach however would require tiny and impractically long cutters and numerous setups with unreasonable machining times (or George's skill with a Dremel tool). So, I made modifications to the full-size engine's design to create a set of machining-friendly scaled models that retain much of the look and feel of the original engine.
Unfortunately, SolidWorks' scaling function doesn't scale the underlying sketches that make up the model. This means that design changes on the scaled model have to be made through the full-size version before it's scaled. With the complex filleting in the original castings creating the majority of the machining headaches, bouncing back and forth between the two models became insanely difficult. So, I decided to start again and created yet another set of 1/3 scale models based upon George's originals.
My models for the block, heads, intake manifold, timing cover, crankshaft, and camshaft are nearly complete. I have a running virtual assembly that includes rods, lifters, and pushrods and a camshaft driven from the crankshaft through a sprocketed timing chain as well as a distributor driveshaft driven from the camshaft through a custom helical gear set. What isn't yet complete is a block oiling scheme although the distributor has been angled around the crankshaft for a distributor-driven oil pump that matches what was done in the full-size engine .
During modeling, partial tool paths were generated using my CAM software so I could test the aging software and computer resources against the models' complexity. The block's lifter valley and the top surfaces of the intake manifold will likely tax my ability to generate the high resolution tool paths that I like to use.
The intake manifold's internal fuel and coolant passages need more work, and all the models will receive minor tweaks along the way. I've developed a bad case of computer burn-out, and I need to start making chips to keep up my enthusiasm for this project.
Material for the major workpieces has been rounded up. The engine will be machined from 7075 aluminum which is a considerably harder alloy than 6061 and capable of durable bearing surfaces and superior finishes. A 3" x 6" x 72" chunk of this was purchased 25 years ago from a building demolition site for just $35. It's now back inside my shop and being sawed into workpieces.
Before anyone asks, I'll gladly share what documentation I end up with after the engine is finished. Please don't ask me for George's original models since they're not mine to share. - Terry
A precise assembly of these five complex parts is a must, but the sources I was using left me with plenty of blanks to fill in. After a frustrating month of endless design and re-design, George Britnell graciously offered me his SolidWorks models of a nearly identical full-size 302 engine. He used these in another thread on this forum to 3-d print a quarter scale version of the same engine. It's fair to say that without his help my own project would have died on the vine.
SolidWorks has a powerful tool that's capable of scaling an entire finished model, and this is just what's required for 3-d printing. George's printer resolution allowed him to retain the rich detail in the engine's original castings, and he was able to print a museum quality model. Trying to replicate his results in metal on my Tormach however would require tiny and impractically long cutters and numerous setups with unreasonable machining times (or George's skill with a Dremel tool). So, I made modifications to the full-size engine's design to create a set of machining-friendly scaled models that retain much of the look and feel of the original engine.
Unfortunately, SolidWorks' scaling function doesn't scale the underlying sketches that make up the model. This means that design changes on the scaled model have to be made through the full-size version before it's scaled. With the complex filleting in the original castings creating the majority of the machining headaches, bouncing back and forth between the two models became insanely difficult. So, I decided to start again and created yet another set of 1/3 scale models based upon George's originals.
My models for the block, heads, intake manifold, timing cover, crankshaft, and camshaft are nearly complete. I have a running virtual assembly that includes rods, lifters, and pushrods and a camshaft driven from the crankshaft through a sprocketed timing chain as well as a distributor driveshaft driven from the camshaft through a custom helical gear set. What isn't yet complete is a block oiling scheme although the distributor has been angled around the crankshaft for a distributor-driven oil pump that matches what was done in the full-size engine .
During modeling, partial tool paths were generated using my CAM software so I could test the aging software and computer resources against the models' complexity. The block's lifter valley and the top surfaces of the intake manifold will likely tax my ability to generate the high resolution tool paths that I like to use.
The intake manifold's internal fuel and coolant passages need more work, and all the models will receive minor tweaks along the way. I've developed a bad case of computer burn-out, and I need to start making chips to keep up my enthusiasm for this project.
Material for the major workpieces has been rounded up. The engine will be machined from 7075 aluminum which is a considerably harder alloy than 6061 and capable of durable bearing surfaces and superior finishes. A 3" x 6" x 72" chunk of this was purchased 25 years ago from a building demolition site for just $35. It's now back inside my shop and being sawed into workpieces.
Before anyone asks, I'll gladly share what documentation I end up with after the engine is finished. Please don't ask me for George's original models since they're not mine to share. - Terry
