Shawn.Walker Wrote:
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> @BloodBlight: so, a completely gear-driven design?
> That could add rigidity/stability, sure. Why do
> you feel it would be "backlash free"? I would
> think switching from belts/lines to gears would
> tend to increase backlash.
Well, I am no engineer, so I could be totally wrong on this. But my understanding is there are two ways you can get backlash. One, from your belts, strings, mounts or whatever stretching. And two, but play in between gears.
In its simplest form there is are only three places that can have play. The arms themselves flexing, the bearing on the upper arm, and the gear on the motor. In theory you backlash limit would be the flex of your arms (unavoidable in any design) plus (ignoring the bearing) the play on a single gear (something that most of the other designs here also have). If these are made of metal and not printed I think you would over torque and force the stepper motor to skip before you saw any backlash.
If you want to use a belt (I don't see how that would reduce backlash), that can be done as well! I recorded a video on that as well, and it is a VERY simple design, but does require two steppers per arm (still using a single motor controller). It would be a direct drive to belt configuration with the belt looping the four points and the motors opposing each other on either arm.
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> @BloodBlight: so, a completely gear-driven design?
> That could add rigidity/stability, sure. Why do
> you feel it would be "backlash free"? I would
> think switching from belts/lines to gears would
> tend to increase backlash.
Well, I am no engineer, so I could be totally wrong on this. But my understanding is there are two ways you can get backlash. One, from your belts, strings, mounts or whatever stretching. And two, but play in between gears.
In its simplest form there is are only three places that can have play. The arms themselves flexing, the bearing on the upper arm, and the gear on the motor. In theory you backlash limit would be the flex of your arms (unavoidable in any design) plus (ignoring the bearing) the play on a single gear (something that most of the other designs here also have). If these are made of metal and not printed I think you would over torque and force the stepper motor to skip before you saw any backlash.
If you want to use a belt (I don't see how that would reduce backlash), that can be done as well! I recorded a video on that as well, and it is a VERY simple design, but does require two steppers per arm (still using a single motor controller). It would be a direct drive to belt configuration with the belt looping the four points and the motors opposing each other on either arm.