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Throttle Body

posted Mar 27, 2013, 7:12 PM by Jay Gross   [ updated Jan 1, 2016, 9:04 PM by Benjamin Gross ]
A physical part was already created by hand for one working steam engine, but our client needed more same-sized copies of the part for additional engines. We scanned in the part, created the profiles used for modeling from the scan data. We imported the profiles and other IGES data into SolidWorks and created the CAD model by hand using the scan reference data to ensure accuracy. Throttle Body part and models displayed with permission from Kevin Sprayberry.

Here is the original part. This 3 inch long part mounts on the front of the steam engine’s boiler. The back of the brass part is hand-fitted to the rough opening in the side of the main inch-thick boiler tube wall.


This is most of the data from the laser scanner for the part.  Here each color is a different scan, our software puts these together based on surface features. The data samples far away from the average surface height are thrown out and the resulting average is used. The object looks solid due to the number of samples. 



These pictures show the simplified scan data. The surface roughness from hand grinding (hidden from view once mounted on the engine) shows up.


These are the profile point sets after importing into SolidWorks. Each IGES layer from the scan data is imported into SolidWorks as a separate 3D sketch in SolidWorks. Each 3D sketch can be a different color or can be hidden from view.  Note that the Low Resolution point set and alignment features are hidden in these pictures. The previous 4 pictures on this web page are the same SolidWorks model with different 3D sketches hidden.


Here is the final product. We did a version with the hexplate and bolt details and one without. The grey square bar is a 4 inch ruler for the client to quickly verify the actual size of the part.