so a while back somebody said it was not recommended to attach the motor right to the wheel and they should use a 1 to 1 gear ratio instead. now with gears being 85% efficient if a 1 to 1 ratio is what you want then why not just hook the wheel right to the motor?
We direct-drive 4- and 5-inch wheels all the time. What doesn’t work so well is attaching a motor to one side of a metal component and the wheel to the other side. It’s always best to support axles in two delrin bearing blocks.
I direct drive wheels all the time. I dunno where you saw someone recommend using gears if you are just doing 1:1. Sometimes… I go so far as to slightly up gear em! Insane!
The VEX motor is a gear-head motor, you should not do a 1:1 with a non-gear-head motor.
Perhaps topics are getting mixed up here.
Directly connecting a wheel (and axle) to a motor might have referred to skipping using a clutch. Doing that puts the motor at risk of being damaged because strong external forces and the effects of stalled wheels are transferred into the motor instead of popping the clutch. That might have been the context of the original statement.
However, putting 1:1 gearing between a motor and a wheel is no substitute for a clutch (if the clutch was the focus of the original statement).
About the topic of whether the motor contains a gear head or not, that seems a bit irrelvant too. The manufacturer of the motor has designed it (chosen it) for use with the other Vex equipment. Broad statements about whether or not some other motors might not be well-suited to directly driving other devices without being “geared up” or “geared down” are useful in the right contexts, but probably don’t apply within the Vex product line.
And I agree, putting 1:1 gearing between a Vex motor and the equipment it is intended to motorize, does seem off-target.
You (DK) probably need to go back to the orignal statement and investigate the context in which it was made. Then, follow-up with further questions, if necessary.
Blake
There is usually a difference between what is heard and what someone is trying to say.
I can see someone saying “it was not recommended to attach the motor right to the wheel” because in that case they may have been referring to using the clutch.
They may have also have had a problem with the wheel and axle sliding out of the motor which requires a collar on the same side of the structure as the motor (I was a bit slow in understanding how to do this) or requires structure on the outside of the wheel.
As for not using gears with a non-gear head motor, again, it depends on what you want to do. If you’re using the motors for conventional movement, then it’s likely the motor has way too little torque to do you any good. On the other hand, I built a reasonably sized gearing mechanism for my ping pong shooter just to UNDO all the gearing in the gear head. The gearhead reduction on the propeller systems I’ve used has been so small, I wouldn’t be surprised to find someone was using a propeller directly attached to the motor. (A google search points me to AXI brushless motors which apparently do just that.)
A final thing to remember is that the best advice someone can give you can still be wrong. A recent thread has someone explaining how an omni drive was not suited for elevation followed one the next page pointing out (months later) that an Omni took third in Worlds. Sometimes someone just fails to accomplish a goal using certain techniques or there are techniques they just don’t like and as a result they’ll try to discourage you from using them. You have to decide for yourself if their advice and reasoning is sound.
it all started here and the first comment is about the direct wheel to motor with a clutch. later i asked why and got the answer that it is good to gear 1 to 1 if you need to move the motor somehow but i still don’t understand why the first person said that it was not recommended if it fits on the robot.
How about this interpretation:
If you can’t fit both a motor and a clutch into some place on a Vex machine that needs a motor; and if your application can survive the losses inherent in using gears or chains; try moving the motor to a place where you will have room to mount both the motor and a clutch, and then use 1:1 gearing and/or a chain to get the motor’s output connected to the thing that needs to be spun.
The gears/chain are only used to transfer the motor’s output forces directly to where they are needed, they are not used to replace the clutch or to modify motor’s speed or torque.
Blake
sorry i am an idiot and forgot the link hahaha. the motors all have clutches too so i am cunfused.
Link: https://vexforum.com/gallery/showimage.php?i=3026&catid=searchresults&searchid=324166
As a general rule, when anyone starts off with “What the hell is that?” or “LOL” (or, in this case, both), I tend to not take their advice too strongly. The poster indicated up front that they didn’t understand it so I wouldn’t worry too much about their advice unless they add some explanations to it.
I found it interesting in that it appeared to have 4" omnis in the front and 5" tires in the back. I’m curious to see what effect that had on it. I think I’ll fiddle with direct drive and different wheel sizes to see what it does in practice.
i saw it or a very similar robot in use and it is pretty cool. it reminded me of FRC team i wanna say #69 the shifters who used this similar belt system to move lunacy balls. it kinda manhandled the cubes though like when other bots had the dual belts like zippy they usually got the cubes in a way that they were stacked neatly where as this bot had them going through the bot every which way but super fast.
mmmm … well by the time I made that post I seriously didn’t noticed the clutch, but yeah as you saw, it has one. Connecting a wheel directly to the motor w/o clutch can damage your motor eventually. Sorry for the confusion and the expression “what the hell is that”, those were just the words that came to my mind when I saw the bot; that doesn’t mean I didn’t knew what I was talking about. I guess I need eyeglasses ;). Cheers.
alright that clears it up. by the way this was never supposed to be a shot at you. in the beginning i was hesitant to even include the link. i just wanted to figure it out and learn a bit in doing so
that’s ok man. the important thing here is to learn; I learn a lot through the forums.