Back-and-forth rotation wheel mechanism

[DraikNova]

I've been trying without success to figure out how to make a compact mechanism that translates normal rotation into back-forth rotation. Any thoughts on how to accomplish such a thing?

[BusterHaus]

Use a 2L beam for rotation, or the cam piece if your linear mechanism is vertical. It doesn't get smaller than that.

[Lego2016Lego]

Good idea.

[dr_spock]

Day 111 of 365: Whack a Jar Jar Binks by dr_spock_888, on Flickr

[Lego2016Lego]

Topic: http://www.eurobricks.com/forum/index.php?showtopic=108493&hl=%2Bwhack+%2Bbinks

[DraikNova]

The thing is, I'm trying to get a back-and-forth rotation, not a back and forth linear motion.

[wumsi]

you could push a worm gear around with the contraption that BusterHaus posted and let that drive a gear

Edited March 31, 2016 by wumsi

[roppie11]

i made a small mechanism for you. it's not that difficult as you may think

you can see everything on the image i think. 2 thin lift arms 3L and 2 thin liftarms 4L. use 2 axles 3L and tadaa ;)

Edited March 31, 2016 by roppie11

[agrof]

Do You have size, part, design limitations?

Do You want an electrical or a mechanical or a combined solution?

How many rotation should be the switch period (1/2 - 1 - 10-...)?

There is couple open questions, but I believe this can be solved in various way.

Here is my 2 cents, didn't try, but there is a serious problem with it: it will stop, as the PF switch reaches the Zero point first. Maybe with enough angular momentum...

Note: the lime pulley wheel is the output, the small assembly represents the switch, and the motor is driven by the switch.

Sorry for not showing a proper working solution, but maybe generates some idea.

Edited March 31, 2016 by agrof

[BusterHaus]

Linear solution, you can also replace the 4L connector with a 3L connector:

[DraikNova]

-snip-

i made a small mechanism for you. it's not that difficult as you may think

you can see everything on the image i think. 2 thin lift arms 3L and 2 thin liftarms 4L. use 2 axles 3L and tadaa ;)

Wow. This is an absolutely perfect solution to my problem.

Thanks for the help everyone!

[Lego2016Lego]

[roppie11]

i have also a short video. filmed with my mobile phone. but i don't know how to share it here. if i copy the link that i see, you probably have to log in to my account to see it. if you know what i mean. nevermind. it should be pretty clear.

[Lego2016Lego]

Look at http://www.eurobricks.com/forum/index.php?showtopic=71241#entry1320172

[roppie11]

it only mentions youtube video's. But its alright. the photo shows enough.

[Lego2016Lego]

Ok.