LEGO TECHNIC : 14950


Technic / 14950

Subject:	Re: Vehicle with square wheels
Newsgroups:	lugnet.technic
Date:	Fri, 9 Dec 2005 20:12:05 GMT
Highlighted:	(details)
Viewed:	6444 times

In lugnet.technic, Jordan Bradford wrote:

I saw this linked on Slashdot:

http://www.prweb.com/releases/2005/12/prweb316686.htm • (snip) I think I’ll try building one of these, if I can get the offset angle to work. It’s 1/4 of 90 degrees, according to the article.

I finally got it to work... (click for bigger images)

...and a short video clip (600k, DivX 5 AVI file).

Enjoy !

Philo

Subject:	Re: Vehicle with square wheels
Newsgroups:	lugnet.technic
Date:	Fri, 9 Dec 2005 20:16:33 GMT
Viewed:	5565 times

Sorry, bad link. Video clip (600k, DivX 5 AVI file).

Philo

Subject:	Re: Vehicle with square wheels
Newsgroups:	lugnet.technic
Date:	Mon, 12 Dec 2005 16:52:23 GMT
Viewed:	5719 times

In lugnet.technic, Philippe Hurbain wrote:

In lugnet.technic, Jordan Bradford wrote:

I saw this linked on Slashdot:

http://www.prweb.com/releases/2005/12/prweb316686.htm (snip) I think I’ll try building one of these, if I can get the offset angle to work. It’s 1/4 of 90 degrees, according to the article.

I finally got it to work... (click for bigger images)

...and a short video clip (600k, DivX 5 AVI file).

Enjoy !

Philo

Fantastic work. I hadn’t even started my attempt. I like your using the battery box as the weight -- it’s very simple and compact.

I noticed from the video that it tends to veer left. Are the wheels losing traction when they’re fully flat?

Subject:	Re: Vehicle with square wheels
Newsgroups:	lugnet.technic
Date:	Mon, 12 Dec 2005 17:50:25 GMT
Viewed:	5857 times

In lugnet.technic, Jordan Bradford wrote: > Fantastic work. I hadn't even started my attempt. I like your using the > battery box as the weight -- it's very simple and compact. > > I noticed from the video that it tends to veer left. Are the wheels losing > traction when they're fully flat? I think the veer left comes from gear backlash. Front and rear wheels are not maintained strictly 22.5° apart and the way it works, this introduces left/right dissymetry. My first attempt used 3 z24 gears with less backlash but of couse I could only offset front and rear by 15° or 30° and it didn't work. Philo

Subject:	Re: Vehicle with square wheels
Newsgroups:	lugnet.technic
Date:	Wed, 14 Dec 2005 21:05:12 GMT
Viewed:	6217 times

In lugnet.technic, Philippe Hurbain wrote: > In lugnet.technic, Jordan Bradford wrote: > > Fantastic work. I hadn't even started my attempt. I like your using the > > battery box as the weight -- it's very simple and compact. > > > > I noticed from the video that it tends to veer left. Are the wheels losing > > traction when they're fully flat? > > I think the veer left comes from gear backlash. Front and rear wheels are not > maintained strictly 22.5° apart and the way it works, this introduces left/right > dissymetry. My first attempt used 3 z24 gears with less backlash but of couse I > could only offset front and rear by 15° or 30° and it didn't work. > > Philo I built one similar to yours last night (I put gears on both sides as an experiment). You're correct that it's the gear backlash that causes the wheels to not quite turn at the same time. Pushing the wheels down manually with your finger is a good way to watch it happen because the process is slower.

Subject:	Re: Vehicle with square wheels
Newsgroups:	lugnet.technic
Date:	Thu, 15 Dec 2005 07:10:08 GMT
Viewed:	7204 times

Here is my attempt (not as elegant as Philo's!) I used old half bushes in a slightly different way. Gear lash seems pretty low. The gear train for the rotating weight needs some work though... http://www.brickshelf.com/gallery/aeh/Square/square1.jpg http://www.brickshelf.com/gallery/aeh/Square/square2.jpg http://www.brickshelf.com/gallery/aeh/Square/square3.jpg http://www.brickshelf.com/gallery/aeh/Square/movie/square.avi cheers, Alexander