It's time for the final drive design. For this project, I decided to use a roller chain instead of the "traditional" belt drive. I intend to use a 1/12 scale chain & sprockets kit from Top Studio, even though they are designed for Moto GP bike kits from Tamiya or Fujimi. But before ordering such a kit I need to design a sort of a mock chain and sprockets, just to assess the frame width and wheel/fender clearances.
After few days of gathering information and learning about chains mathematics (e.g. calculate the number of teeths, sprocket diameters), I finally managed to finalize the design and dimensions. I don't intend to have accurate sprocket ratio or pitch, just to have something to help getting the clearances right.
Just to give you an idea of the scale, here are the chain and sprockets data I came up with:
Pitch = 0.955 mm
Roller diameter = 0.5 mm
Roller width = 0.6 mm
Sprockets thickness = 0.5 mm
Driver sprocket outside diameter = 6 mm
Number of teeth on the transmission side sprocket = 18
Driven sprocket outside diameter = 18.843 mm
Number of teeth on the wheel side sprocket = 60
Of course these will change once I get the Top Studio chain kit, but it was a good learning exercise on how to design a chain and sprockets in Inventor. Plus that due to this exercise I discovered that the primary transmission plate has to be adjusted a bit to clear the chain. Also the oil tank's diameter had to be reduced from 13 mm to 12 mm, to clear the transmission plate. The rear fender will have a cut off on the left side, but I will not model that on the virtual model but do it directly on the fender part.
Later I will have to decide how to attach the sprocket on the transmission axle - I would like to be able to turn the rear wheel and both sprockets on the final/real scale model.
Here are some photos:
After few days of gathering information and learning about chains mathematics (e.g. calculate the number of teeths, sprocket diameters), I finally managed to finalize the design and dimensions. I don't intend to have accurate sprocket ratio or pitch, just to have something to help getting the clearances right.
Just to give you an idea of the scale, here are the chain and sprockets data I came up with:
Pitch = 0.955 mm
Roller diameter = 0.5 mm
Roller width = 0.6 mm
Sprockets thickness = 0.5 mm
Driver sprocket outside diameter = 6 mm
Number of teeth on the transmission side sprocket = 18
Driven sprocket outside diameter = 18.843 mm
Number of teeth on the wheel side sprocket = 60
Of course these will change once I get the Top Studio chain kit, but it was a good learning exercise on how to design a chain and sprockets in Inventor. Plus that due to this exercise I discovered that the primary transmission plate has to be adjusted a bit to clear the chain. Also the oil tank's diameter had to be reduced from 13 mm to 12 mm, to clear the transmission plate. The rear fender will have a cut off on the left side, but I will not model that on the virtual model but do it directly on the fender part.
Later I will have to decide how to attach the sprocket on the transmission axle - I would like to be able to turn the rear wheel and both sprockets on the final/real scale model.
Here are some photos:
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