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Subject: 
Re: building thicker technic axles
Newsgroups: 
lugnet.technic
Date: 
Tue, 27 Nov 2001 23:20:55 GMT
Viewed: 
735 times
  
In lugnet.technic, Thomas Avery writes:
In lugnet.technic, Mark-Jan Bastian writes:
Hello,

When I see those very big cranes, I wonder how the pivoting points
at the bottom of the large booms can hold it out. Are two or more
beams with a technic axle enough to handle the enormous force ?

I was wondering if it's possible to build thicker axles from lego,
for example, using 2x2 round bricks with axles through them, supported
by plates with holes and beams on the side.

The 2x2 round bricks can then be supported by round corner bricks:

http://guide.lugnet.com/partsref/search.cgi?q=corner+round

These corner bricks have to be mounted sideways, and supported
by sideway-mounted plates. At least 4 corner pieces are needed to
contain a 2x2 round brick. A plate-contruction around the corner
pieces is needed to make it all solid. The corner stones should be
supported by bricks to the sides and underneath it.

Not very usual construction, but maybe worth to experiment with.
I don't have any round corner stones, but have seen them in
60..70's lego sets a long time ago.

Will this idea work ?

Mark-Jan

Probably, but I think an easier solution is to have multiple shearing planes
on your axle (a normal Technic axle). You can kind of see this idea in my crane:
http://www.texbrick.com/creations/crawler_crane/crawler/cwl5.html

I don't know how much shear force an axle can take, but I know it's quite a
bit. I've never tested one to failure, but I'd bet it's many 10's of
kilograms (20... 30?). If you spread out the shear force on multiple planes
of failure (potential failure, that is ;-) then the shear capacity of your
axle is greatly increased.

TJ

One thing I noticed about Technic Axles is that they seem to have a bit of
rational flex. You have to have something with a bit of mass being rotated about
the axle to notice it. Look at my znap/technic ferris wheel here ...

<http://www.brickshelf.com/cgi-bin/gallery.cgi?f=6513>

The center pivot is a pair of 12L Technic Axles with some zanp parts for the
load bearing. I have noticed that if I stop the motor abruptly, the mass of the
ferris wheel tries to keep turning and the axle flexs a little ( ~5-deg ) and
then recovers back to the correct spot.

Ray



Message has 1 Reply:
  Re: building thicker technic axles
 
(...) same thing on the helicoptor rotor I've made. To counter this I made a 'one-direction'-drive that 'slipped' when the motor stooped. See (URL) (fifth item in list) and (URL) the axle driving the rotor also had to bee strengthened. I put an axle (...) (23 years ago, 29-Nov-01, to lugnet.technic)

Message is in Reply To:
  Re: building thicker technic axles
 
(...) Probably, but I think an easier solution is to have multiple shearing planes on your axle (a normal Technic axle). You can kind of see this idea in my crane: (URL) don't know how much shear force an axle can take, but I know it's quite a bit. (...) (23 years ago, 27-Nov-01, to lugnet.technic)

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