The machining of the Camshaft lobes is done using a 4th Axis on the CNC. The Camshaft is cut from 5/16″ drill rod and uses the OD as the bearing surfaces. There are bearing surfaces at each end and between each cylinder. The cylinders alternate between having the intake lobe closer to the front and the exhaust lobe closer to the front. This is done to simplify the design of the intake and exhaust manifolds. I am going to machine a single cylinder’s pair of lobes in one machine set up, thus will have four setups on the CNC.
A 3D CAD model of the camshaft sections is created for both the intake manifold lobe in front and the exhaust lobe in front. A feature is added as shown below and highlighted with the red arrow to create a coordinate system the CAM software as a reference for the tool paths. There are four separate tool paths. I could have gotten away with two tool paths then adjusted the starting rotation of the work piece before each machining operation, but I opted to make the setups as easy as possible even if it required a little more work before hand.
Then each of the four tool paths are simulated.
All four machining operations will be done as close to the collet chuck as possible to minimize the stick out, so a method needs to be used that allows the work piece to be extended and reoriented before each machine run. The work piece is prepared as shown below with a flat machined at the far end.
A simple carpenter’s level is modified with an aluminum guide that rides in the flat, then is secured to the work piece with rubber bands.
This provides a simple and accurate way to return the rotation of the work piece to a known zero point. I am able to easily discern a tenth of a degree of rotation when jogging the A axis.
The stick out is simply measured with a caliper to the face of the collet.
Once the CNC is touched off on all axis, it is ready to run.
The cut is done in three passes, two roughing with a .025″ step down and .025″ step over. The finishing pass uses a .0075″ step over. Mist coolant is used.
The work piece is stepped out of the collet before each of the four machining operations.
And the machining of the Camshaft lobes is complete. The remaining machining and finishing work for the Camshaft will be performed on the lathe.