ATD Design and Fabrication Services

At the heart of observational sciences lies the instruments and equipment to gather data. Scientists frequently have strong engineering streaks and can envision and even render to paper schemes to achieve the measurements they want. Enter ATD’s Design and Fabrication Services.

Since its earliest days and springing from a field of research also strongly dependent on observational studies – the Sun – NCAR has had a first-class machine shop that over the years has evolved to its modern day version in ATD. Complete with the most advanced CAD capabilities, and computer numerical controlled machine tools. DFS has produced an impressive array of specialized instruments and equipment. Over 960 projects dating to 1963 have been supported.

Jobs are brought to the group in many different forms, from conceptual information which requires input from the design group, to complete detailed designs generated by the customer. On occasion, the customer supplies solid (electronic) models of the instrument and its components via the internet as e-mail attachments or FTP files. These files are then opened using any one of a variety of Computer Aided Machining (CAM) software tools which are maintained in house. These CAM programs produce the tool paths required to produce the part. The material is selected and mounted in the machine tool, the tool path is downloaded to the machine via RS-232 link and the machining operations are performed. This method minimizes the requirement for detailed mechanical drawings and can greatly shorten the time of production.

Here we demonstrate how an instrument is made, from original concept thru design, fabrication and testing, before it is ready for research use. We have chosen the 4 Channel Chemical Ionization Mass Spectrometer as our example.

In the early stages of the design, hand drawn sketches are effective in communicating the basic concepts and requirements of the instrument.

CAPTION: Conceptual sketches used to determine basic dimensional parameters of the Main OH Inlet for the 4 channel CIMS instrument.

CAPTION: This basic sketch was used to determine the routing of various gas and vacuum plumbing lines, as well as the basic layout of the main components of the HNO3 Inlet for the 4 Channel CIMS.

Once the basic concept is conveyed to the designer, a set of solid models of the components are detailed and put into an assembly model. A very useful tool used during the design development process is provided by the software vendor SolidWorks - Download Software . The solid models can be shipped via the internet to the customer, opened and viewed using the free viewer. The viewer provides the ability to rotate the images, do cross section views and zoom in and out to magnify details of the models. A customer has the ability to do a design review at a remote location and discuss the design simultaneously with the designer. This has proven to be an extremely effective method of communicating design iterations between the designer and the customer.

CAPTION: A special cutaway view is used to look "inside" the assembly. Having this capability aides the designer and the Scientist in determining proper treatment of all aspects of the design. An extremely useful tool, at this stage, is the SolidWorks Viewer.

CAPTION: Different colors are used for separate components for better visualization of the assembly. This is the solid model representation of the HNO3 Inlet.

Once the solid model is produced a design review is held with all interested parties. Upon review and approval by the investigator, the parts are detailed and hard copies are printed so that all dimensional information is available to the instrument maker in the shop.