2 wire vs. 3 wire speed drive

  1. 5 years ago

    Jarred

    11 Dec 2013 Greenfield, Indiana 1115A

    Hey guys. We tore down the robot today and thought about how the robot is too slow from what we'd like. We plan on having a gear ratio for speed. Possibly 3:1? My question is whether it would be better to use two 2 wire 393 motors at a speed ratio, or three 3 wire 269 motors at a speed ratio.

    Thanks in advance :D

  2. TommyMcM

    11 Dec 2013 Zionsville, IN 7701Z

    First off, there are no such things as 3 wire 269 motors. A 3:1 gear ratio is excessive and will just burnout your motors if you plan on having anything on the chassis. It all depends on your strategy(aggressive, passive, defensive, etc.) , planned weight, and also drive type (wheels, treads, holonomic, etc) Really you should only go to about 3:2 for safety (I had a 2:1 earlier on in the year with 4 393s total which burnt out in competition environment)

    With more information it would be easier to help you.

  3. edjubuh

    11 Dec 2013 V5 Beta Moderator West Lafayette, IN

    @Jarred Hey guys. We tore down the robot today and thought about how the robot is too slow from what we'd like. We plan on having a gear ratio for speed. Possibly 3:1? My question is whether it would be better to use two 2 wire 393 motors at a speed ratio, or three 3 wire 269 motors at a speed ratio.

    Hey Jarred,

    EDIT: Tommy appears to have beaten me to it, albeit slightly rudely :P...
    What do you mean by 3 wire 269 motors? I presume you mean you will be using 2-to-3 wire converters (Motor Controller 29s).

    If you have the motors, go for 393s on the drivetrain. You will likely be going slow regardless of motor type if you are using on 2 or 3 motors on your chassis. Most robots will dedicate 4 or 6 motors to the chassis. With four motors, I would recommend going for regular high-torque 393 motors that are geared slightly for speed, to taste. With 6 motors, you should be able to go straight for 393s geared for speed. That does, of course, differ for robots depending on whether they are heavier or lighter.

    Anywho, I try to stay away from the 269 motors whenever possible, except on mechanisms that need to be super lightweight or don't need much power - like scoring intakes.

    Hope this helps,
    Elliot

  4. Jarred

    11 Dec 2013 Greenfield, Indiana 1115A

    @Team7706 First off, there are no such things as 3 wire 269 motors. A 3:1 gear ratio is excessive and will just burnout your motors if you plan on having anything on the chassis. It all depends on your strategy(aggressive, passive, defensive, etc.) , planned weight, and also drive type (wheels, treads, holonomic, etc) Really you should only go to about 3:2 for safety (I had a 2:1 earlier on in the year with 4 393s total which burnt out in competition environment)

    With more information it would be easier to help you.

    Haha not sure why I said 269. I meant regular 3 wire motors. And I just realized my wording was a bit wrong. I meant either 4 393s. Or 6 3 wires. And the robot won't be super lightly but won't be overly heavy. Probably around 13lbs. I think that's normal? Haven't weighed it yet.

  5. TommyMcM

    11 Dec 2013 Zionsville, IN 7701Z

    @Jarred Haha not sure why I said 269. I meant regular 3 wire motors. And I just realized my wording was a bit wrong. I meant either 4 393s. Or 6 3 wires. And the robot won't be super lightly but won't be overly heavy. Probably around 13lbs. I think that's normal? Haven't weighed it yet.

    I would recommend 4 393s at 3:2, that's what my very first bot this year was and it drove nicely with good control and no burnout.

  6. JesseCRN

    11 Dec 2013 Indianapolis, IN 323Z

    @Jarred Hey guys. We tore down the robot today and thought about how the robot is too slow from what we'd like. We plan on having a gear ratio for speed. Possibly 3:1? My question is whether it would be better to use two 2 wire 393 motors at a speed ratio, or three 3 wire 269 motors at a speed ratio.

    Thanks in advance :D

    I would personally use the full 10 motor limit. For our robot this year, we are using 6 motors internally geared for speed (1.6:1) on the drive, 2 motors geared 1:5 on the lift, and 2 motors on the intake (1:1). These are all 393 motors.

    3:1 is a little to fast for this game. It is true you need speed to get around and score fast, but if you die in the first 30 seconds of the match because of motor overheating, that is not good. I would stick with 2:1 max. 1.6:1 is pretty close to a 2:1 ratio, so that might be a good option.

    I would only use 393 motors on the drive, or lift. You don't really need 393 motors on the intake. 269's will work fine. Why would you only use 2-3 motors for your drive? That does not give you a lot of torque. I would at least stick 4 motors on the drive. That leaves you 6 more motors for your lift and intake.

    We might end up having an 8 motor drive by the end of the year, but we will see what happens tomorrow :)

    I'm always glad to help fellow IN teams ;)

  7. JesseCRN

    11 Dec 2013 Indianapolis, IN 323Z

    @Jarred Haha not sure why I said 269. I meant regular 3 wire motors. And I just realized my wording was a bit wrong. I meant either 4 393s. Or 6 3 wires. And the robot won't be super lightly but won't be overly heavy. Probably around 13lbs. I think that's normal? Haven't weighed it yet.

    Ok, that sounds better. I would go with a 6 motor drive with all 269's. Either of those options would work nicely though. We had a 4 393 motor tank drive last year. It worked great.

    @Team7706 I would recommend 4 393s at 3:2, that's what my very first bot this year was and it drove nicely with good control and no burnout.

    So basically internally geared 393 motors ;)

  8. Jarred

    11 Dec 2013 Greenfield, Indiana 1115A

    @Team7706 I would recommend 4 393s at 3:2, that's what my very first bot this year was and it drove nicely with good control and no burnout.

    Ok thanks! Ill try out having 6 269s and also 4 internal speed 393 motors on Thursday

  9. edjubuh

    11 Dec 2013 V5 Beta Moderator West Lafayette, IN

    @Jarred Ok thanks! Ill try that out on Thursday and see how it goes. Oh and would chain be preferable to low strength gears?

    Depends on high strength chain vs regular chain. The old/regular chain has this nasty tendency to break under any reasonable stress. Also, if your gear/chain reduction only takes two gear/sprockets and you can fit them right next to each other, you might as well just use gears. If you need to use idler gears (gears that are not directly powered or attached to a wheel, or being used in your reduction), then you should be using high strength chain.

    @Jesse323Z So basically internally geared 393 motors ;)

    ssshhh :)

    I'm a personal fan of this all-Hoosier thread... Don't need no out-of-staters ;)

  10. TommyMcM

    11 Dec 2013 Zionsville, IN 7701Z

    @Jarred Ok thanks! Ill try that out on Thursday and see how it goes. Oh and would chain be preferable to low strength gears?

    I always use chain for the drive as it is easier to use for the drive as it does not invert spin direction through gears.

  11. JesseCRN

    11 Dec 2013 Indianapolis, IN 323Z

    @Jarred Ok thanks! Ill try out having 6 269s and also 4 internal speed 393 motors on Thursday

    I would use HS chain unless the sprockets are close to each other. At that point, I would just use LS gears. Chaining is a lot easier to build than gearing.

    EDIT: Well goodness. Elliot beat me.

    @edjubuh I'm a personal fan of this all-Hoosier thread... Don't need no out-of-staters ;)

    So, maybe we just all need to get on a Google Hangout? :P

  12. Jarred

    11 Dec 2013 Greenfield, Indiana 1115A

    Ok thanks for the help everyone! And yes definitely hs chain if anything. I tried ls chain last year ( didn't go so well :/ ) I think I'll try chain first if applicable.

    Go Hoosiers!! :D

  13. JVN

    11 Dec 2013 Moderator, VRC Q&A, OLC Q&A, League Play, Teachers/Coaches, Event Partner, Worlds Q&A, VEX Tech Support Greenville, TX

    All,
    I deleted several off-topic posts, and split a few more into their own thread.

    Just a reminder to try to keep things on topic. Some topics are better handled via Skype, PM, or email instead of on a public forum.

    -John

 

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