3 ms·

The core problem with the dynamixels is cost. I'm hesitant to use them in any situation they could get trashed because they are so expensive. Add on that they a

The core problem with the dynamixels is cost. I'm hesitant to use them in any situation they could get trashed because they are so expensive. Add on that they are harder to control and it's a recipe for a niche product. Having used them I loved them, but they aren't a tool I reach for at first. But now that you've brought them up I kind of want to use them for something. But why this board has RC PWM Servo ports? Because it's a cheap easy way of interfacing with things. More importantly, it let's you hook Brushed/Brushless ESCs up fairly easily to get things moving with motors that draw more than 1 amp. 1) DC Brushed - Spark ESC https://www.amazon.com/SPARK-Motor-Controller-REV-Robotics/dp/B0187YCAFI https://www.amazon.com/SPARK-Motor-Controller-REV-Robotics/d... (Disclaimer - I know the owner of Rev, he's a friend) 2) This is really a function of scale more than anything. But yes, they are expensive. 3) With the advent of 3d printing it's at least manageable to put something around them But I agree with you that most of these are incredibly annoying.

supernovae 10y ago
Spark Revs are nice :) we just had your friend come out and replace one on our practice robot
VLM 10y ago
Speaking of big motors and big torques its interesting to consider CNC machine tool conversion technology ... Admittedly continuous use, industrial level indestructibility and temperature levels means expense, but if you want 400+ oz=in of torque for a wheel perhaps, you could do worse than CNC controller hardware perhaps driven by something other than CNC software. At some point you have a 5 volt TTL interface thats as simple as direction and step. You'll be spending maybe $200 per axle but you look at the price of 400+ oz-in servos or gear motors plus drive circuitry and suddenly its not that bad. 1000+ oz-in is not out of line for the larger machine tool conversions. Standard NEMA motor mounts etc. You take 200 steps/rev stepper and add 10-step microstepping driver like a geckodrive and theres 2000 steps/rev at 400+ oz/in with a simple TTL interface for maybe $200 (plus power, and steppers are hungry beasts)
- Teever 10y ago
  Could you provide a link to some of these $200 devices for reference?
  - VLM 10y ago
    Something like a geckodrive G251 single axis stepper driver for $89 good to 3.5 amps combined with a NEMA 23 stepper one of the lower current 1.8 amp "long" types $48 on amazon for 340 oz/in torque. That's about $140. That's 68% of budget for 85% of specified torque. Its easy to find a NEMA 34 with over 600 Oz/in for $60 on amazon but it'll probably draw 6 amps at 600 oz/in and you'll need a more expensive controller. Something like a geckodrive G201X is rated to 7 amps at $127 which just barely makes spec. The worlds cheapest stepper paired with the worlds fanciest most indestructible controller is probably unrealistic.

supernovae 10y ago

Spark Revs are nice :) we just had your friend come out and replace one on our practice robot

VLM 10y ago

Speaking of big motors and big torques its interesting to consider CNC machine tool conversion technology ... Admittedly continuous use, industrial level indestructibility and temperature levels means expense, but if you want 400+ oz=in of torque for a wheel perhaps, you could do worse than CNC controller hardware perhaps driven by something other than CNC software. At some point you have a 5 volt TTL interface thats as simple as direction and step. You'll be spending maybe $200 per axle but you look at the price of 400+ oz-in servos or gear motors plus drive circuitry and suddenly its not that bad. 1000+ oz-in is not out of line for the larger machine tool conversions. Standard NEMA motor mounts etc. You take 200 steps/rev stepper and add 10-step microstepping driver like a geckodrive and theres 2000 steps/rev at 400+ oz/in with a simple TTL interface for maybe $200 (plus power, and steppers are hungry beasts)

Teever 10y ago
Could you provide a link to some of these $200 devices for reference?
- VLM 10y ago
  Something like a geckodrive G251 single axis stepper driver for $89 good to 3.5 amps combined with a NEMA 23 stepper one of the lower current 1.8 amp "long" types $48 on amazon for 340 oz/in torque. That's about $140. That's 68% of budget for 85% of specified torque. Its easy to find a NEMA 34 with over 600 Oz/in for $60 on amazon but it'll probably draw 6 amps at 600 oz/in and you'll need a more expensive controller. Something like a geckodrive G201X is rated to 7 amps at $127 which just barely makes spec. The worlds cheapest stepper paired with the worlds fanciest most indestructible controller is probably unrealistic.