One motor rd4b

  1. last week

    Bhargav S.

    Sep 12 Maryland 952C

    Do you guys thing one v5 motor will hold up a rd4b with a cap intake, or would two motors be better?

    @Bhargav S. Do you guys thing one v5 motor will hold up a rd4b with a cap intake, or would two motors be better?

    It depends. You could do it quite easily I believe but the gear ratio you choose will play a big role.

  2. The Electrobotz

    Sep 12 Answer Virginia 20181X

    @Bhargav S. Do you guys thing one v5 motor will hold up a rd4b with a cap intake, or would two motors be better?

    It depends. You could do it quite easily I believe but the gear ratio you choose will play a big role.

  3. NightsRosario

    Sep 12 Reisterstown/Catonsville, MD 3922A
    Edited last week by NightsRosario

    @Bhargav S. Do you guys thing one v5 motor will hold up a rd4b with a cap intake, or would two motors be better?

    2 will always be better, but with good bracing 1 will suffice

    Also, i see that Md tag

    this is also assuming that you use a gear ratio that can lift what you need

  4. Bhargav S.

    Sep 12 Maryland 952C

    Ok thanks! if was thinking a torque motor with a 1:5

  5. Bhargav S.

    Sep 12 Maryland 952C

    Maryland for the win!

  6. NightsRosario

    Sep 12 Reisterstown/Catonsville, MD 3922A

    @Bhargav S. Ok thanks! if was thinking a torque motor with a 1:5

    1:5 torque would work perfectly with a 1m V5 DR4B. just make sure you brace properly

  7. The Electrobotz

    Sep 12 Virginia 20181X

    @Bhargav S. Ok thanks! if was thinking a torque motor with a 1:5

    Yeah. As @NightsRosario said, you could totally go with a 1:5 ratio with one V5 motor(assuming this is 200rpm). You might even be able to go with a 1:3 ratio if your build quality is good enough and if the cap intake is light.

  8. briancole

    Sep 12 Utah 4270C

    We had a three motor dr4b last year- little bit different but the concept is the same. Basically just stick the motor in the middle of a universal axle powering the dr4b and you'll go up straight just fine.

  9. NightsRosario

    Sep 12 Reisterstown/Catonsville, MD 3922A

    @briancole We had a three motor dr4b last year- little bit different but the concept is the same. Basically just stick the motor in the middle of a universal axle powering the dr4b and you'll go up straight just fine.

    you really don't have to do that. with enough bracing just powering one side would suffice

  10. Mark Finley

    Sep 13 Las Vegas, Nevada 6891B

    I built a 1 motor dr4b that works with a torque 393. It doesn't work with the high speed V5 though so I have to wait until vex ships the gears for motors.

  11. callen

    Sep 13 Braintree, MA, USA
    Edited last week by callen

    @Mark Finley I built a 1 motor dr4b that works with a torque 393. It doesn't work with the high speed V5 though so I have to wait until vex ships the gears for motors.

    Likely because the stall torque for the V5 isn't that much higher than for the 393, nowhere close to the power output ratio that can be achieved. So running the 393 at 120 rpm v. running the V5 at 200 rpm more than makes up for the lower stall torque. With the set-up I think you're describing, the 393 would require more than 30% more torque than the V5 to stall it. So you're probably in that reasonably large region beyond what the 200 rpm V5 can handle and yet not straining the torque 393. Changing the V5 to 100 rpm should allow it to handle the lift noticeably better than the 393. Then the V5 would require 50% more torque to stall it than the torque 393 does.

  12. Mark Finley

    Sep 13 Las Vegas, Nevada 6891B

    @callen Likely because the stall torque for the V5 isn't that much higher than for the 393, nowhere close to the power output ratio that can be achieved. So running the 393 at 120 rpm v. running the V5 at 200 rpm more than makes up for the lower stall torque. With the set-up I think you're describing, the 393 would require more than 30% more torque than the V5 to stall it. So you're probably in that reasonably large region beyond what the 200 rpm V5 can handle and yet not straining the torque 393. Changing the V5 to 100 rpm should allow it to handle the lift noticeably better than the 393. Then the V5 would require 50% more torque to stall it than the torque 393 does.

    Noice

    I know that high torque V5 motors are 6:1 gear ratio what is the gear ratio in high torque 393's?

  13. Rick TYler

    Sep 13 Teachers/Coaches, Event Partner, V5 Beta Moderator Redmond, Washington Founder of Exothermic Robotics

    @Mark Finley Noice

    I know that high torque V5 motors are 6:1 gear ratio what is the gear ratio in high torque 393's?

    The 100 RPM V5 gears are a 36:1 reduction, 200 RPM are 18:1 and the 600 RPM are 6:1. The "high torque" option is 36:1.

    The gear reductions on the 393s are similar. I cannot remember where I heard it, but I'm pretty sure that the free RPM of the 393 motor is about 3,600, just like the V5 motor, which would mean the 100 RPM gears are 36:1.

  14. callen

    Sep 13 Braintree, MA, USA
    Edited last week by callen

    @Rick TYler The gear reductions on the 393s are similar. I cannot remember where I heard it, but I'm pretty sure that the free RPM of the 393 motor is about 3,600, just like the V5 motor, which would mean the 100 RPM gears are 36:1.

    I haven't seen the free speed for the 393, so I can't speak to that. But the available output speeds for the 393 are 120 rpm, 160 rpm, and 240 rpm. So if you're right about that 3600 rpm, then they would be 30:1, 22.5:1, and 15:1.

    The V5s have a noticeably bigger spread, which I expect we'll find more useful. For example, using 600 rpm you only need one pair of external gears to reach 4200 rpm as opposed to the compound gears needed for a 393, even if it's turbo.

  15. meng

    Sep 13 Singapore 8059

    @callen I haven't seen the free speed for the 393, so I can't speak to that. But the available output speeds for the 393 are 120 rpm, 160 rpm, and 240 rpm. So if you're right about that 3600 rpm, then they would be 30:1, 22.5:1, and 15:1.

    Always thought the output speed of 393 (as shipped) is 100 rpm (and not 120 rpm)?

    https://www.vexrobotics.com/motors.html#Outputs

  16. callen

    Sep 13 Braintree, MA, USA

    @meng Always thought the output speed of 393 (as shipped) is 100 rpm (and not 120 rpm)?

    https://www.vexrobotics.com/motors.html#Outputs

    Hmm... I was going by this:
    https://www.vexrobotics.com/276-4840.html#Product_Specs

    Seems VEX is disagreeing with itself. :(

  17. meng

    Sep 13 Singapore 8059

    @callen Hmm... I was going by this:
    https://www.vexrobotics.com/276-4840.html#Product_Specs

    Seems VEX is disagreeing with itself. :(

    Lol. The vex virus strikes again.

    Unless they have changed the specs for the newer 393, else I am quite sure it is 100 rpm. Coz all along the high speed gear is 1.6 times the speed, and turbo is 2.4 tImes the speed. Only possible if the initial speed is 100 rpm.

  18. tabor473

    Sep 13 V5 Beta Tester OYES, WPI

    @meng Lol. The vex virus strikes again.

    Unless they have changed the specs for the newer 393, else I am quite sure it is 100 rpm. Coz all along the high speed gear is 1.6 times the speed, and turbo is 2.4 tImes the speed. Only possible if the initial speed is 100 rpm.

    Ya the 120 figure comes from actual tests under no load. The motor has so much torque it is able to spin all the way up to 120 rpm. Tests with 393s actually show a variance in no load free speed from 105-120 rpm iirc. The tiniest amount of load drops it down to 100 rather quickly so motors dont always ship able to spin at 120 rpm.

    The higher gear ratios spin fast enough that they have load from the metal gears that they only reach 100% not the equivalent 120% of their "top" speed.

  19. meng

    Sep 13 Singapore 8059

    @tabor473 Ya the 120 figure comes from actual tests under no load. The motor has so much torque it is able to spin all the way up to 120 rpm. Tests with 393s actually show a variance in no load free speed from 105-120 rpm iirc. The tiniest amount of load drops it down to 100 rather quickly so motors dont always ship able to spin at 120 rpm.

    The higher gear ratios spin fast enough that they have load from the metal gears that they only reach 100% not the equivalent 120% of their "top" speed.

    That explains the difference!
    Makes a lot of sense now.

    But maybe vex should be more specific when putting down numbers.

 

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