![](https://static.wixstatic.com/media/12fdfe_7c882d0fb2134c94a5e371be5afe8865~mv2.png/v1/fill/w_378,h_600,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_7c882d0fb2134c94a5e371be5afe8865~mv2.png)
Justin W.H. Yuen
Reverse Engineering Project: Making a Solid Model of a Hobby Propeller
![](https://static.wixstatic.com/media/12fdfe_9a33a42afc814918bd4be1837d3e844e~mv2.jpg/v1/crop/x_160,y_0,w_1104,h_897/fill/w_321,h_261,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_9a33a42afc814918bd4be1837d3e844e~mv2.jpg)
![](https://static.wixstatic.com/media/12fdfe_1555e2784f794a868b4fcf73e53ab623~mv2.png/v1/crop/x_15,y_17,w_213,h_212/fill/w_269,h_268,al_c,lg_1,q_85,enc_auto/12fdfe_1555e2784f794a868b4fcf73e53ab623~mv2.png)
Hobby Propeller (left) and Solid Model (right)
Modeling this object with multiple lofts would be difficult and painful considering its longest dimensions were no more than 4 cm. Instead, I took a creative approach by using the contour of the blades and tracing the top view of the propeller. To measure easier, I cut 2 of the blades off.
![](https://static.wixstatic.com/media/12fdfe_85bbcb22d872473e97f690cd46fa0796~mv2.jpg/v1/crop/x_141,y_68,w_885,h_659/fill/w_322,h_240,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_85bbcb22d872473e97f690cd46fa0796~mv2.jpg)
![](https://static.wixstatic.com/media/12fdfe_a1cab56ad38d4c2f8370c72b85224060~mv2.jpg/v1/crop/x_243,y_73,w_692,h_506/fill/w_328,h_240,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_a1cab56ad38d4c2f8370c72b85224060~mv2.jpg)
Using a contour gauge (left) and tracing the contour with a pencil.
![](https://static.wixstatic.com/media/12fdfe_5bf7189e8029487fba53f9bc2b51817b~mv2.png/v1/fill/w_329,h_199,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_5bf7189e8029487fba53f9bc2b51817b~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_2e30bf1461fe4825a3e783441bb72fd8~mv2.jpg/v1/crop/x_237,y_0,w_973,h_607/fill/w_329,h_205,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_2e30bf1461fe4825a3e783441bb72fd8~mv2.jpg)
![](https://static.wixstatic.com/media/12fdfe_b5cdbbc3215b413e97a67d2bee1edc18~mv2.png/v1/crop/x_18,y_0,w_436,h_258/fill/w_323,h_191,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_b5cdbbc3215b413e97a67d2bee1edc18~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_2633a903b15f47d797904af781e6306e~mv2.png/v1/crop/x_20,y_7,w_233,h_120/fill/w_322,h_166,al_c,lg_1,q_85,enc_auto/12fdfe_2633a903b15f47d797904af781e6306e~mv2.png)
Scanned tracing of the contour gauge (top left), radius of curvature determined geometrically (top right), sweep profile from inserted image feature on SolidWorks (bottom left), and resulting sweep (bottom right).
![](https://static.wixstatic.com/media/12fdfe_04f2e8b053ab4f66865812a2d4358334~mv2_d_2550_3300_s_4_2.jpg/v1/crop/x_554,y_1222,w_771,h_1004/fill/w_207,h_270,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_04f2e8b053ab4f66865812a2d4358334~mv2_d_2550_3300_s_4_2.jpg)
![](https://static.wixstatic.com/media/12fdfe_7210fdf28f99487eb3bde67188cb5fdc~mv2.jpg/v1/crop/x_617,y_166,w_519,h_487/fill/w_260,h_244,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_7210fdf28f99487eb3bde67188cb5fdc~mv2.jpg)
![](https://static.wixstatic.com/media/12fdfe_fca036e7371d467196d09a91d82bee0c~mv2.jpg/v1/crop/x_493,y_0,w_814,h_644/fill/w_260,h_206,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_fca036e7371d467196d09a91d82bee0c~mv2.jpg)
The most difficult part was getting a decently leveled picture of the top view. Using a leveled printer scanner would typically do the trick, but I couldn't get a clear picture. So I came up with an idea to use spray paint. The idea came from spray paintings I used to make using stencils.
![](https://static.wixstatic.com/media/12fdfe_6cc52b0b6715416689c97a81a434fcb4~mv2.jpg/v1/crop/x_445,y_162,w_538,h_504/fill/w_266,h_249,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_6cc52b0b6715416689c97a81a434fcb4~mv2.jpg)
![](https://static.wixstatic.com/media/12fdfe_82276889ef6f42f8a9af4011b0f3d3dc~mv2.jpg/v1/crop/x_225,y_0,w_586,h_548/fill/w_257,h_240,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/12fdfe_82276889ef6f42f8a9af4011b0f3d3dc~mv2.jpg)
Red spray paint (top left), taped propeller blade (top right), propeller painted over (bottom left), and stenciled mark beneath propeller (bottom right)
![](https://static.wixstatic.com/media/12fdfe_b5dedbf85aaa474a89b660a18aa2e9ae~mv2.png/v1/crop/x_24,y_0,w_335,h_275/fill/w_338,h_277,al_c,lg_1,q_85,enc_auto/12fdfe_b5dedbf85aaa474a89b660a18aa2e9ae~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_289151ae35184218964c732366869355~mv2.png/v1/fill/w_333,h_227,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_289151ae35184218964c732366869355~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_45293ff179b74f988cd73c601f3348cb~mv2.png/v1/fill/w_322,h_274,al_c,lg_1,q_85,enc_auto/12fdfe_45293ff179b74f988cd73c601f3348cb~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_9b6678f6c4a14b1e94c6a13d7e4cce74~mv2.png/v1/crop/x_275,y_9,w_336,h_260/fill/w_271,h_210,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_9b6678f6c4a14b1e94c6a13d7e4cce74~mv2.png)
Stenciled spray paint (top left), tracing of the painting (top right), extrude cut preview (bottom left), and final result of the propeller blade (bottom right)
![](https://static.wixstatic.com/media/12fdfe_cd3f891374d145e6be1e99507ef939aa~mv2.png/v1/fill/w_329,h_192,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_cd3f891374d145e6be1e99507ef939aa~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_9db75e86fd08440fb899217ddb7490e3~mv2.png/v1/crop/x_6,y_32,w_501,h_305/fill/w_331,h_202,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_9db75e86fd08440fb899217ddb7490e3~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_420a60d1bcb045d5964a63faac266208~mv2.png/v1/fill/w_323,h_190,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_420a60d1bcb045d5964a63faac266208~mv2.png)
![](https://static.wixstatic.com/media/12fdfe_d54c3abfd006449d80b1c9a8f4aa1d36~mv2.png/v1/fill/w_311,h_128,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/12fdfe_d54c3abfd006449d80b1c9a8f4aa1d36~mv2.png)
Extrusion of hub (top left), extrude cut under the blade (top right), circular pattern (bottom left), final model (bottom right)
![propeller.JPG](https://static.wixstatic.com/media/12fdfe_410ee7e2c1174a84aae732f4d055b2dd~mv2.jpg/v1/fill/w_624,h_490,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/propeller_JPG.jpg)
Other than avoiding multiple lofts to model the blade, I now have an easier way to redesign the contour and shape of the blade.