Holding 7 Arc Seconds

TOP: The Verify mode in Mastercam X5 can show workpiece material removal on this mill/turn part at any stage of manufacturing. Surfaces are color-coded to indicate what tool performed the operation, and if there was too much or too little material removal in comparison to the model. BOTTOM: Slice view visualization is the key to creating programs for perfect execution on CNC equipment from the outset. This view even allows the programmer to slice the part to see the effect of the program on areas that are not generally visible to the naked eye.

Software Bisque Inc. is an unusual name for a manufacturing company. Its original claim to fame was SkyX Astronomy Software, developed by the company's founder, Steve Bisque, and used by academic and amateur astronomers throughout the world for observatory control, deep space imaging, and scientific discovery. The company began manufacturing robotically controlled telescope mounts about 12 years ago in response to the growing need for high precision, compact mounts for easy deployment in mobile or remote applications.

Seven arc seconds is an unusual hardware specification. It signifies that the robotic mount allows a CCD telescope to track its target with a deviation of no more than 0.5" across a distance of 10 miles before the software applies any correction algorithms. This level of precision is essential for finding and locking onto targets in deep space and is possible by the proprietary gearing with minimal backlash, precision machined bearings, and other mechanical components.

In the two and a half years he has been with the company, CAM Programmer Dennis Arnold has been involved in developing manufacturing protocols for three additional products beyond Software Bisque's original Paramount ME mount. He begins this work by seamlessly importing Steve Bisque’s SolidWorks part models into Mastercam Mill and Lathe CAM software (from CNC Software Inc., Tolland, CT.) Then he embarks on an expeditious but extremely careful process of laying down toolpaths and electronically monitoring the results.

There is literally no surface where the behavior of the tool and its result on the workpiece goes unobserved. Maintaining tight tolerances, while precisely chamfering, even in close proximity to walls and other nearby surfaces, is executed safely to eliminate almost all deburring. “Our motto here is ‘Manufacture On Purpose, Not by Accident,’” Arnold says.

Increasing the Odds
A veteran Mastercam user with 25 years experience, Arnold’s job is to create cleanly executable manufacturing processes for four CNC mills and two mill/turn systems, all with FANUC controls.

“I do everything I can to increase the odds that our prototype parts can be manufactured the first time, without any mistakes. This reduces the cost of scrap and really helps us get our products to market faster,” Arnold says.

Increasing the odds of mistake-free, first piece manufacturing begins with having post processors that require no additional coding at the machine. For the mills, this means taking the generic posts provided by his Mastercam reseller and editing them to his liking.

During Software Bisque’s recent new product development cycle, Arnold was challenged to manufacture all the parts of three robotic mounts in a very short amount of time. The only way this would happen was to push the corporate mistake-free philosophy of manufacturing to the limit.

Surface Fly Overs
Arnold uses Mastercam’s primary simulation modes, Backplot and Verify, to detect most programming errors before the part ever is put on the machine. Backplot provides an animated visualization of the tool as it moves through the various toolpath sequences, so programmers can see that the sequence of machining operations are complete and there are no crashes. Verify shows workpiece material removal at various stages of machining. Surfaces are color-coded to indicate what tool is to perform the operation and whether there is too little or too much material removal in comparison to the model.

Verify is the primary tool Arnold uses to evaluate the effectiveness of his toolpath programming. Instead of sitting passively and waiting for Verify to churn up its results, Arnold grabs the mouse as if he were at the controls of a fighter plane and flies over the part at various magnifications and distances to ensure that everything looks exactly as it should.

Minimized Deburring; Smooth Transition for Changes
Burrs are a particular concern.

Arnold explains, “For a product of this quality, burrs are absolutely unacceptable. They can produce fit and wear problems with mating surfaces. What is more, our customers, who are primarily scientists, would not be able to trust us if there were cosmetic imperfections anywhere on the product, even if they did not affect its performance.”

Software Bisque’s robotically controlled telescopes are precision manufactured so that they have tracking accuracy to within 7 arc seconds.

Deburring can be a time-consuming and expensive manual procedure. During the programming process, Arnold creates chamfers along any edge where burrs might develop. He uses Verify in the turbo mode, which is like time-lapse photography to fly over edges and check that chamfering is at an appropriate depth and width to compensate for burrs that might be created by a particular tool.

He also uses a special feature of Mastercam that allows him to shorten or extend the toolpath so that the chamfer mill can move in very close to nearby walls without nicking them. With this procedure, he has been able to eliminate numerous hours that would have been required for manual deburring.

Occasionally while programming, Arnold will catch a mistake that needs correction in the design. He communicates the problem to Steve Bisque who makes the needed modification in SolidWorks and places it on the network server. Arnold brings in this new geometry as a new level in Mastercam. Then he uses Mastercam’s Rechain feature to reapply existing toolpaths to the new geometry.

“Just because there are edits here and there, you do not have to make huge changes to the program that you have already done. If it is just a couple features, which is normally what it is, then it is a very smooth transition to complete the program,” Arnold says.

Watching the Cartoon
When the part is ready for machining, Arnold meets with the machine operator and runs through a simulation of the entire manufacturing process.

“We call this a cartoon, and it allows our machine operator to watch all the steps that the program is going through. The tools that are being used for a given operation appear on the screen. He can use this as a guide for running the part and ensuring that all the tools he needs are available in the machine.”

Proven Under the Stars
|Recently, the Software Bisque manufacturing team created all the parts and assembled three identical prototypes for a new robotic telescope mount design. All of the CAM programming, manufacturing, and assembly of the prototypes were completed in less than three months. That is about a 90% development cycle reduction from the 18 months it took for Software Bisque to produce the prototypes for its original hardware product. Arnold attributes this impressive product development cycle reduction to his ability to manufacture parts successfully 90% to 95% of the time on the first run.

He says that the prototypes have passed their initial visual inspections and functional testing with excellence. However, the real test will come under the stars when the units demonstrate their ability to lock onto and track distant heavenly bodies with an uncompensated deviation of 7 arc seconds or less.

Software Bisque Inc.
Golden, CO
www.bisque.com

CNC Software Inc. (Mastercam)
Tolland, CT
www.mastercam.com