If I have a motor with a shaft diameter of 7mm, how do I use it to drive an axle made with 4/40 threaded rod? If I use a gear, do they have gears with 7mm holes? Are there coupling devices I could use? I have a 48 tooth spur gear already mounted on the axle. How could I employ that in the solution?
George
Hi obrien135,
I am not sure i understand what you are trying to connect in which way.
Are you looking to convert the 7mm shaft to attach 4-40 thread instead ?
We do not have such a shaft, but we have one that could maybe fit with some adaptation.
This is made for 6mm (1/4") shaft and has a 4-40 thread to mount a wheel, where you could screw a 4-40 threaded rod.
Maybe you can give us some picture ?
Those drawings you sent me look ok but would I be able to hone the fitting out so it would fit a 7mm shaft? Would that be the correct thing to do?
Which part in your assembly has a 7mm shaft ? I only see a tiny motor there.
I am not going to use that motor. I don’t have any other pictures of it right now. The motor I am getting might have 7mm shafts but I’m not sure yet. That is one of the things I am trying to determine. The motor is supposed to arrive Saturday.
George
An axle made out of 4-40 threaded rod might be too soft.
Just trying to adjust the mesh between the gears will put too much pressure on the rod and bend it.
Also, a 7mm shaft motor seems very big compare to the Axle.
Maybe you should use something else as your axle ? Or use two motor that can be mounted on either side of the box.
Like that one:
obrien135
You ordered the motor from RadioShack which look to be this one:
http://rsk.imageg.net/graphics/product_images/pRS1-19138845w345.jpg
We have similar motor in our store, they are not 7mm shaft but about 5.4mm.
The Dagu Gear Motor Pair - 90 degree Shaft are very similar and you can look at their Datasheet for size.
Most people use them with wheels directly on the motor, it can be done easily with an adapter like This one.
Best way would still be to buy a set of two motor from us and connect the wheels directly, that way you don’t need the tiny 4-40 axle.
There is even kits with motor/adaper/wheel 65mm Wheel and DC Motor (Pair)
The DC motor pair with hubs and wheels seem like a potentially good option, but how am I supposed to know the RPM, torque and current draw ratings of those motors? They aren’t even identified on that webpage.
The motor used in that kit have the following specifications:
[font=Verdana, Arial, Helvetica, sans-serif]Electrical Characteristics:[/font]
[font=Verdana, Arial, Helvetica, sans-serif]
]Operating Voltage Range: 3~7.5V/:m]
]Rated Voltage: 6V/:m]
]Max. No-load Current(3V): 140 mA/:m]
]Max. No-load Current(6V): 170 mA/:m]
]No-load Speed(3V): 90 rpm/:m]
]No-load Speed(6V): 160 rpm/:m]
]Max. Output Torque: 0.8 kgf.cm/:m]
]Max. Stall Current: 2.8 A/:m][/font][font=Verdana, Arial, Helvetica, sans-serif]Operating Conditions:
]Rated Load: 0.2 kgf.cm/:m]
]Operating Temperature: -10~+60 ℃/:m]
]Storage Temperature: -30~+85 ℃/:m]
]Motor Type: 130/:m]Mechanical Characteristics:
]Output Mode: 2 sides/:m]
]Gear Ratio: 1:120/:m]
]Max. Diameter of Output Axle: 5.4 mm/:m]
]Net Weight: 45 g/:m][/font]
I got it working with a gear I had around. I just had to ream, it out with a drill to make it fir the 5.4mm shaft. see links.
youtube.com/watch?v=7HRLSb8_d_o&feature=youtu.be
youtube.com/watch?v=gbgvPYOi3WI&feature=youtu.be
It’s alive…!
Nice to see you got it working.
