If you would "pull-up"...

[Matt Adams]

Originally Posted by patrickrd

I think this would be a good example of where a worm gear would be useful. It will provide a large gear ratio and will not slip unless powered.

You need to be a little careful with worm gears, they CAN be back driven. The van door motor for instance can be back driven. Some sort of a ratcheting mechanism might be a better choice, since it's a firm mechanical stop.

2 cents...

Matt

[Matt Leese]

Originally Posted by Matt Adams

You need to be a little careful with worm gears, they CAN be back driven. The van door motor for instance can be back driven. Some sort of a ratcheting mechanism might be a better choice, since it's a firm mechanical stop.

2 cents...

Matt

Perhaps I'm mistaken, but I was under the impression that a fundemental aspect of the worm gear was that it was impossible for it to be back driven. I've never seen the van door motors backdriven so it may be something else you've seen. Worm gears can break however as the stress of resisting back driving can be great.

Matt

[M. Hicken]

i agree with Ken, all you have to do is get the large ~14"throw cylinder and hook cable up to it, its more than strong enough. but a globe motor or 2 would surfice

[Joe3]

Actually...whether a worm gear can be backdriven or not is dependent on the pitch of the teeth. If you give yourself a decent lever arm, such as a wrench, on the end of the van door shaft, it is backdriven quite easily.

[KenWittlief]

I thought the van door motor has an internal clutch mechanism, adjustable with the allen screw - so the motor would slip when pushed against a hard stop.

maybe thats what is 'backdriving' - is the motor really turning or is the output shaft slipping internally?

I could be mistaken on this

(I could be mistaken about everything really :^)

[maxgebhardt]

I dont think it will start slipping! last year we used it to winch up our forklift, and when it got stuck (on two occations), rather than stop, it ripped through some fairly thick plastic, and another time ripped a 6 inch nail sideways, clean through about 2" of pine, it darn near split the nail in half.

[Mr. Ivey]

O.K. So far you guys have listed using the window motors, a pnumatic piston, and two globe motors. Now yes you could use any motor out of the box, as long as you gear it correctly, but besides the window motors, globe motors, and pnumatic motors. What is a quick way to move these bots upward. I'm almost thinking something like a track that the bot can run up that doesn't actually pull, but pushes against the track.
Ivey

[KenWittlief]

other ways? dont forget we are allowed to use springs - you could come up with a mechasim that is spring loaded - once you hook on the enegry is release and up we go!

or how about retractable wheels! dont lift your bot, raise your feet :c)

[robo-gordo]

About the Van Door Motors:
They can be back-driven. It has nothing to do with internal clutches, or anything else. (The drill motors, however have anti-backlash pins).

You can open the vand-door motors covers up by prying off about 6 or 7 plastic tabs. Inside you will see a big plastic gear connected to a work gear. Take a large (>8") vise-grip, and attach it to the output shaft. If you turn the wrench, you will see the plastic gear inside backdrive the work gear. The fact that the gear is plastic and liberally coated with grease may have something to do with it.

For those of you who have had the van-door motor stay: perhaps you had your victor's in brake mode, which prevents a motor from spinning when a neutral signal is received.

Also, believe it or not, the Fisher-Price motors are more powerful than the van door's. Check the specs.

[ahecht]

Originally Posted by Mr. Ivey

O.K. So far you guys have listed using the window motors, a pnumatic piston, and two globe motors. Now yes you could use any motor out of the box, as long as you gear it correctly, but besides the window motors, globe motors, and pnumatic motors. What is a quick way to move these bots upward. I'm almost thinking something like a track that the bot can run up that doesn't actually pull, but pushes against the track.
Ivey

You could use the Window Motor with a tape drive to push yourself up, but IIRC, the pushing force of the tape is only around 100lbs, so you would need a light robot. On the other hand, using the Window Motor with a tape to pull yourself up might not be a bad idea...

[Frank(Aflak)]

Originally Posted by Mr. Ivey

O.K. So far you guys have listed using the window motors, a pnumatic piston, and two globe motors. Now yes you could use any motor out of the box, as long as you gear it correctly, but besides the window motors, globe motors, and pnumatic motors. What is a quick way to move these bots upward. I'm almost thinking something like a track that the bot can run up that doesn't actually pull, but pushes against the track.
Ivey

I bet pneumatics would be fastest.

We will probably use a van door/winch setup this year, though, as we have a design that makes getting the hook on the bar quite easy.

[srjjs]

Tape measures ought to do nicely.

[generalbrando]

I don't want to reiterate the idea of pneumatics too much, but it seems like some are talking just about the new motor we have available this year and the rest aren't clear.

My thought with pneumatics is that you can easily put up a stiff arm 9' tall (10 from the floor, 9 from the platform) and then on the end of it have a nice wide pneumatic piston with a clasp/hook/whatever on it. You can activate the raising with a telescope or some simple lighter pneumatics - then you can lift up in an instant with the other one on the end. I think this might be a good approach for rookies since my experince is that pneumatics tend not to go wrong as often as the rest of the stuff.

[Gui Cavalcanti]

We've trusted the CIMs for two years straight as drive motors, and they haven't let us down yet.

We're using a drill for getting ourselves off the ground, but that's all I'm saying right now