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Subject: 
Re: Two Design Problems
Newsgroups: 
lugnet.build
Date: 
Thu, 9 Nov 2000 01:24:54 GMT
Viewed: 
815 times
  
Anders Isaksson <isaksson.etuna@REMOVEebox.tninet.se> wrote in message
news:G3oBM1.4MI@lugnet.com...
Damraska skrev i meddelandet ...

Problem 1:
I want to use a single motor to (slowly) raise a vertical shaft (e.g., a
Technic axel mounted vertically) 8 to 16 studs.  After raising the shaft • to
full extension, the same motor needs to engage the shaft, causing it to
rotate.  While rotating, the shaft does not elevate further.  When the • motor
reverses directions, it disengages from the shaft and then (slowly) • lowers
it.  There will be a fair amount of weight at the top of the shaft.

Not tested at all, just an idea, sorry for my lack of English:

Use a worm drive (is that the right word for the 'screw' gear?) and • straight
cogged pieces (word?) to do the raising. When the cogged pieces are raised • to
the top by the worm, the normal gear engage the axle, and the worm 'slips'
(not the right word).

You probably need to balance out the weight a bit, strings and pulleys and • a
counterwight somewhere should fix that.

Trying to draw, fixed font recommended:

           |   | XX
---        |  -|--------     top plane, motor
           |  ===            gear
           |   |
   --------|-  |             'bottom' plane, with axle
     |   ===== |             cog, gear
     |>        |
     |> |      |
     |><|>     |             cog, worm
     |><|>     |
     |><|>     |
     |> |      |
     |> |      |
        |      |
      ===== =======          gear, gear

You're not saying anything about size, and how much 'hidden' space there • is,
so I don't know if this is a feasible solution, although it should work,
technically.

Anders, that's perfect.  Your mock-up is similar to what I already tried,
but I never thought of using a second shaft, parrallel to the first, to
drive the worm gear and raise the rack.  Thanks much for that schematic.  :)

Problem 2:
I want to build fully functional (i.e., motorized) landing pads a la • Space:
1999.  A given landing pad needs to measure approximately 70 studs by 70
studs and lower into a housing 15 to 20 bricks deep (or even deeper). • After
the pad lowers approximately 10 studs, doors need to slide in from under • the
deck to close off the hole left by the cross shaped portion of the • landing
pad that descends to the hanger level. All of the machinery must reside
below the landing pad, but size of said machinery does not really matter. • I
think some sort of pulley system would probably work best but I cannot • think
of anything that will support the weight and remain stable.

The same method as above for raising and lowering, and then a gear train • (plus
strings, pulleys perhaps) for the sliding doors. You might have a problem • with
the load on the motor here, perhaps two or more in parallell are needed.

I tried something like this and load was definitely a problem.  I may try
again, using two or three motors inline, if the forklift trick Jason
suggested does not pan out.  I am still rather new to Technic construction
(in terms of actually designing things that work and move, rather than using
the parts for mecha).  It takes some getting used to.

Thanks for the help and ideas,

  -Doug

^V^^V^
I am:  Damraska@Excite.com
Minifig Suns:  http://pages.prodigy.net/damraska/



Message is in Reply To:
  Re: Two Design Problems
 
Damraska skrev i meddelandet ... (...) Not tested at all, just an idea, sorry for my lack of English: Use a worm drive (is that the right word for the 'screw' gear?) and straight cogged pieces (word?) to do the raising. When the cogged pieces are (...) (24 years ago, 7-Nov-00, to lugnet.build)

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