One-Man Shop Off to the Races
David Gilbert became so good at making difficult parts that his one-man garage-based operation, started in 1989, had burgeoned into a 10-person, 12-machine shop by 2007. At this point, managing the shop was taking all of his time away from what he loved doing best, making challenging parts. So, Gilbert sold the business and went back to his one-man shop.
Gilbert’s expertise in making geometrically complex 3D components brought him business from a wide range of esoteric sources including universities and government agencies. Today, however, an almost insatiable demand for sophisticated, lightweight racing car suspension parts provides him with all the manufacturing challenges he can handle.
He preps his models, designs work-holding solutions, and programs the parts in Mastercam. Then he manufactures the components with multiaxis equipment that includes a 4-axis machining center, two 5-axis machining centers, and a lathe with live tooling.
Each year, Gilbert’s racing customers keep raising the ante in terms of the challenging nature of the parts they are requesting. He shared, “It seems that Mastercam has evolved perfectly in time with the complexity of the components. Every time the engineers design a more difficult to manufacture component or structure, Mastercam has stepped up to the plate to provide tools that let me do what I need to do faster and easier. Their model manipulation and repair improvements over the last few years have been tremendous, and I am happy dealing with the solids, which are the standard these days. Being able to open more than a single instance of Mastercam software at the same time makes it very easy to work back and forth between 2D and 3D.”
It typically takes Gilbert between 10 and 16 hours to program and set up the most complex parts with approximately one third to one half of that time devoted to geometry manipulation and programming.
“With complex shapes, I can’t simply pick a toolpath type and go with it. I essentially break the part into several segments and use different toolpath strategies for the different segments,” said Gilbert. “None of these parts are simple, even the ones that appear so.”
Weight reduction is always on the mind of racing component customers. So, Gilbert frequently finds himself having to machine very thin walls. He uses Mastercam’s CAD for CAM capabilities to design workholding solutions that not only include unique fixtures, but also use sacrificial material support structures within the part itself. Then he chooses Dynamic Motion toolpaths to reduce cutting forces on the part’s thin walls. Frequently, he works in different layers of Mastercam to create workholding solutions as he is writing multiaxis manufacturing programs.
Many of these thin-walled parts have sections that are tubular in shape with wall thicknesses as thin as 0.060” with a final surface finish of 12 to 16 Ra. Prior to polishing, the outer finish of the part is machined to approximately 30 Ra to 50 Ra. The outer features are rough milled, then the inner portion is turned, then the outer surfaces are finish milled. Tool sizes vary from a 3/16” diameter ball end mill down to a 1/32” diameter ball end mill. “In our turn features, we finish them all with diamond tooling to a mirror finish,” said Gilbert.
The choice of hundreds of toolpaths provides Gilbert with the ability to be selective as to how he will approach the part. “I’ll use a raster toolpath for areas that are simple to access—I don’t have to worry about too much material on a specific place—and I’ll use a scallop if I’m working down toward a point or from a point upward. I basically use all of the available paths,” he noted.
Sometimes weight reduction includes the use of exotic lightweight materials such as lithium-aluminum, which is 7% lighter than standard aluminum alloys, but about eight times more expensive. So, scrap is not an option. These materials can have unique machining characteristics and Gilbert relies on the ease with which Mastercam toolpaths can be chained to devise the most appropriate strategy for the material and geometry in question.
During the winter months, after the racing season is over and Formula One engineers release their new designs, Gilbert finds himself straight out making all sorts of unique complex parts with 5-week or less lead times. Things tail off during the race season and he has time to pursue some of his personal interests, like designing his own custom motorcycles and a custom modular home he has had built to order. He designed the home in Mastercam and uses the software for motorcycle part designs as well.