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Subject: 
Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Fri, 3 Mar 2006 20:27:31 GMT
Viewed: 
6509 times
  

(cross posted to my blog and BayLUG Mindstorms mailing list)

Have you ever tried building a scissor lift in LEGO? I’m working on a project that calls for that kind of mechanism to lift it up, like those food service trucks at the airport. It is based on an “X” shaped arrangement, which, like the two parts of a scissors pivot at the middle. By bringing together the two bottom (or top) ends, the top is lifted into the air.

The approach I took was to use Technic worm gears (like a screw) with a rack gear on it. By turning the worm gears the rack gear should move along its length, which moves the two bottom ends together, elevating the top. The problem is that LEGO gears just aren’t up to the load this places on them, and the teeth skip. I motorized it, gearing down the motor to get more torque, but the gears would rather skip than lift the weight.

Has anyone out there successfully built this kind of scissor lift mechanism in LEGO to lift a nontrivial weight? If so please reply here, comment on my blog or email me any tips you may have. Thanks!

--Bill.

   
         
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Fri, 3 Mar 2006 20:56:07 GMT
Viewed: 
6559 times
  

"Bill Ward" <bill@wards.net> wrote in message news:IvKJHv.1xLK@lugnet.com...
(cross posted to
<http://www.brickpile.com/2006/03/03/scissor-lift-in-technic/
my blog> and BayLUG Mindstorms mailing list)

Have you ever tried building a scissor lift in LEGO? I'm working on a
project
that calls for that kind of mechanism to lift it up, like those food
service
trucks at the airport. It is based on an "X" shaped arrangement, which,
like the
two parts of a scissors pivot at the middle. By bringing together the two
bottom
(or top) ends, the top is lifted into the air.

The approach I took was to use Technic worm gears (like a screw) with a
rack
gear on it. By turning the worm gears the rack gear should move along its
length, which moves the two bottom ends together, elevating the top. The
problem
is that LEGO gears just aren't up to the load this places on them, and the
teeth
skip. I motorized it, gearing down the motor to get more torque, but the
gears
would rather skip than lift the weight.

Has anyone out there successfully built this kind of scissor lift
mechanism in
LEGO to lift a nontrivial weight? If so please reply here,
<http://www.brickpile.com/2006/03/03/scissor-lift-in-technic/#comments
comment
on my blog> or email me any tips you may have. Thanks!

--Bill.

Posting to Lugnet so others can see.

My $.02, but I'm no mechanical genius:

Why don't you use one of those gear holders that holds a worm gear and 24t
gear in it.  Since the worm gear can slide along an axle, make the axle
stationary, but the gear mechanism where it can slid back and forth.  You
can then attach technic beams to the cross axle going through the 24t gear.
As the motor shaft turns the worm gear, it will cause a rotational force to
the scissor extending it, and the whole mechanism should be able to slide
(because when the scissor extends, it pulls opposite side together).

Hope it works.  That's only a theory!!!!

Rob
www.brickmodder.net

    
          
      
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Fri, 3 Mar 2006 21:07:40 GMT
Viewed: 
6566 times
  

"Rob Hendrix" <rob.removebeforesending@msltc.org> wrote in message
news:IvKKqA.255E@lugnet.com...
My $.02, but I'm no mechanical genius:

Rob,
     You are one of the above.

Bob Fay

    
          
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sun, 5 Mar 2006 21:48:07 GMT
Viewed: 
6509 times
  

In lugnet.technic, Rob Hendrix wrote:
My $.02, but I'm no mechanical genius:

I deg to biffer.

Why don't you use one of those gear holders that holds a worm gear and 24t
gear in it.  Since the worm gear can slide along an axle, make the axle
stationary, but the gear mechanism where it can slid back and forth.  You
can then attach technic beams to the cross axle going through the 24t gear.
As the motor shaft turns the worm gear, it will cause a rotational force to
the scissor extending it, and the whole mechanism should be able to slide
(because when the scissor extends, it pulls opposite side together).

Hope it works.  That's only a theory!!!!

That may just be crazy enough to work.  I'll try it!

   
         
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Fri, 3 Mar 2006 21:06:26 GMT
Viewed: 
6515 times
  

In lugnet.technic, William R. Ward wrote:
   (cross posted to my blog and BayLUG Mindstorms mailing list)

Have you ever tried building a scissor lift in LEGO? I’m working on a project that calls for that kind of mechanism to lift it up, like those food service trucks at the airport. It is based on an “X” shaped arrangement, which, like the two parts of a scissors pivot at the middle. By bringing together the two bottom (or top) ends, the top is lifted into the air.

The approach I took was to use Technic worm gears (like a screw) with a rack gear on it. By turning the worm gears the rack gear should move along its length, which moves the two bottom ends together, elevating the top. The problem is that LEGO gears just aren’t up to the load this places on them, and the teeth skip. I motorized it, gearing down the motor to get more torque, but the gears would rather skip than lift the weight.

Haven’t actually built one, but one other possibility may be to use string rather than gearing directly.

How many scissors are there in your lift? On the real ones I’ve seen they often have a hydraulic cylinder going from the bottom scissor to the top one, you gain some mechanical adveantage doing it that way, but it may be difficult to emulate in LEGO.

Let us know how it goes.

ROSCO

    
          
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sun, 5 Mar 2006 20:48:47 GMT
Viewed: 
6600 times
  

In lugnet.technic, Ross Crawford wrote:
   Haven’t actually built one, but one other possibility may be to use string rather than gearing directly.

On a winch? That’s an intriguing idea.

   How many scissors are there in your lift? On the real ones I’ve seen they often have a hydraulic cylinder going from the bottom scissor to the top one, you gain some mechanical adveantage doing it that way, but it may be difficult to emulate in LEGO.

Just one scissor.

    
          
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Mon, 10 Apr 2006 23:05:19 GMT
Viewed: 
8637 times
  

In lugnet.technic, William R. Ward wrote:
   In lugnet.technic, Ross Crawford wrote:
   Haven’t actually built one, but one other possibility may be to use string rather than gearing directly.

On a winch? That’s an intriguing idea.

Update: I ended up using string and it worked beautifully! Well, it has weight distribution issues (one side goes up before the other) but I’ll work on that later...

   
         
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sat, 4 Mar 2006 00:06:37 GMT
Reply-To: 
Geoffrey Hyde <gDOThyde@bigpondDOTnet*stopspam*DOTau>
Viewed: 
6624 times
  

Some photos of what you've tried so far would help a great deal.

I was wondering if it would be possible to see how cloesly you're matching
up the worm gears to the rack gears, theoretically, it should be possible,
but if you're using more than one worm gear against a rack gear, the
construction has to hold it in place and the worm thread on the worm gear
needs to be precisely aligned with the line of the rotational thread of the
worm gear next to it or your worm gears will be out of rotational sync with
each other - unless you're only using one worm gear on each rack part.


Cheers ...

Geoffrey Hyde



"Bill Ward" <bill@wards.net> wrote in message news:IvKJHv.1xLK@lugnet.com...
(cross posted to
<http://www.brickpile.com/2006/03/03/scissor-lift-in-technic/
my blog> and BayLUG Mindstorms mailing list)

Have you ever tried building a scissor lift in LEGO? I'm working on a
project
that calls for that kind of mechanism to lift it up, like those food
service
trucks at the airport. It is based on an "X" shaped arrangement, which,
like the
two parts of a scissors pivot at the middle. By bringing together the two
bottom
(or top) ends, the top is lifted into the air.

The approach I took was to use Technic worm gears (like a screw) with a
rack
gear on it. By turning the worm gears the rack gear should move along its
length, which moves the two bottom ends together, elevating the top. The
problem
is that LEGO gears just aren't up to the load this places on them, and the
teeth
skip. I motorized it, gearing down the motor to get more torque, but the
gears
would rather skip than lift the weight.

    
          
      
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sat, 4 Mar 2006 02:44:36 GMT
Viewed: 
6731 times
  

"Geoffrey Hyde" <g.hyde@bigpond.net.au> wrote in message
news:IvKtn1.16vD@lugnet.com...
Some photos of what you've tried so far would help a great deal.

http://www.ozbricks.com/bobfay/orthogli.htm

http://www.ozbricks.com/bobfay/yaxis.htm

http://www.ozbricks.com/bobfay/newmill.htm

These may  give some ideas. I made a nut out of two 8 tooth gears and used a
string of worm gears as a lead screw, but I cannot find the  picture. The
best configuration would be that of a scissors jack for a car. Hard to do
with Lego.

     
           
      
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sat, 4 Mar 2006 06:26:25 GMT
Reply-To: 
Geoffrey Hyde <gDOThyde@bigpondDO+ihatespam+TnetDOTau>
Viewed: 
6779 times
  

Those are some interesting milling machines there Bob.  How do you think
they'd look if built in the newer studless beams?  Do you think there'd be
any insurmountable rigidity problems building with studless beams?

I noticed you had one long worm gear going through a paired set of
oppositely rotating 16t/24t gears.  I guess this was to keep the worm gear
stable while the gears just held it in place without moving?

http://www.ozbricks.com/bobfay/Pict0127.jpg - this pic here, on the
"newmill" page is what I'm talking about.


Cheers ...

Geoffrey Hyde



"Bob Fay" <rgfay@earthlink.net> wrote in message
news:IvL0y3.24MI@lugnet.com...

"Geoffrey Hyde" <g.hyde@bigpond.net.au> wrote in message
news:IvKtn1.16vD@lugnet.com...
Some photos of what you've tried so far would help a great deal.

http://www.ozbricks.com/bobfay/orthogli.htm

http://www.ozbricks.com/bobfay/yaxis.htm

http://www.ozbricks.com/bobfay/newmill.htm

These may  give some ideas. I made a nut out of two 8 tooth gears and used
a string of worm gears as a lead screw, but I cannot find the  picture.
The best configuration would be that of a scissors jack for a car. Hard to
do with Lego.


     
           
      
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sat, 4 Mar 2006 14:57:31 GMT
Viewed: 
6730 times
  

"Geoffrey Hyde" <g.hyde@bigpond.net.au> wrote in message
news:IvLB88.1D9t@lugnet.com...
Those are some interesting milling machines there Bob.  How do you think
they'd look if built in the newer studless beams?  Do you think there'd be
any insurmountable rigidity problems building with studless beams?

I noticed you had one long worm gear going through a paired set of
oppositely rotating 16t/24t gears.  I guess this was to keep the worm gear
stable while the gears just held it in place without moving?

http://www.ozbricks.com/bobfay/Pict0127.jpg - this pic here, on the
"newmill" page is what I'm talking about.


Cheers ...

Geoffrey Hyde

Actually the gears cannot rotate as they are meshed with each other. This
causes them not only to support the screw, but act as a nut creating linear
motion for the slide.

I am not sure how well the studless beams will work for my interests. When a
cutter hits the material it is cutting, Lego reminds me that it is a toy.
The studs do make rigid structures possible. I hope to gain some new
experience when the NXT comes out in the Fall. I will surely have to change
my thinking.

Bob
--
http://www.ozbricks.com/bobfay/

    
          
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sun, 5 Mar 2006 20:51:14 GMT
Viewed: 
6601 times
  

In lugnet.technic, Geoffrey Hyde wrote:
Some photos of what you've tried so far would help a great deal.

I'm sure they would.  Sorry I just haven't taken any yet.  But this thread has
given me some great ideas to try...

I was wondering if it would be possible to see how cloesly you're matching
up the worm gears to the rack gears, theoretically, it should be possible,
but if you're using more than one worm gear against a rack gear, the
construction has to hold it in place and the worm thread on the worm gear
needs to be precisely aligned with the line of the rotational thread of the
worm gear next to it or your worm gears will be out of rotational sync with
each other - unless you're only using one worm gear on each rack part.

The worm gears are aligned carefully, and they seem to mesh fairly well, but I
think ultimately rack gears and worm gears in LEGO just aren't a good match.  I
think part of my problem is that there is enough space along the axle for it to
deflect away from the rack, giving room for the teeth to skip.

    
          
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sun, 5 Mar 2006 21:06:18 GMT
Viewed: 
6609 times
  

"Bill Ward" <bill@wards.net> wrote in message news:Ivo9xE.1oBF@lugnet.com...
In lugnet.technic, Geoffrey Hyde wrote:
The worm gears are aligned carefully, and they seem to mesh fairly well,
but I
think ultimately rack gears and worm gears in LEGO just aren't a good
match.  I
think part of my problem is that there is enough space along the axle for
it to
deflect away from the rack, giving room for the teeth to skip.

They do not mesh. We need a rack  like this ///////////
not ||||||||||| .

Bob

--
http://www.ozbricks.com/bobfay/

   
         
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sat, 4 Mar 2006 23:39:22 GMT
Viewed: 
6407 times
  

Bill, I Built A Scissor Lift with a pneumatic piston in the middle. http://www.brickshelf.com/cgi-bin/gallery.cgi?f=34275 http://news.lugnet.com/technic/?n=9290 HTH Chris

    
          
     
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Sun, 5 Mar 2006 21:52:59 GMT
Viewed: 
6527 times
  

In lugnet.technic, Chris Daniel wrote:
   Bill, I Built A Scissor Lift with a pneumatic piston in the middle. http://www.brickshelf.com/cgi-bin/gallery.cgi?f=34275 http://news.lugnet.com/technic/?n=9290

I think I’ll stick with gears for now, as my pneumatics inventory is weak and I think it would get too bulky. But I’ll keep that in mind...

   
         
   
Subject: 
Re: Scissor Lift in LEGO?
Newsgroups: 
lugnet.technic
Date: 
Mon, 6 Mar 2006 17:26:35 GMT
Viewed: 
7621 times
  

Have you ever tried building a scissor lift in LEGO? I’m working on a project
that calls for that kind of mechanism to lift it up, like those food service
trucks at the airport. It is based on an “X” shaped arrangement, which, like
the two parts of a scissors pivot at the middle. By bringing together the two
bottom (or top) ends, the top is lifted into the air.

The approach I took was to use Technic worm gears (like a screw) with a rack
gear on it. By turning the worm gears the rack gear should move along its
length, which moves the two bottom ends together, elevating the top. The
problem is that LEGO gears just aren’t up to the load this places on them,
and the teeth skip. I motorized it, gearing down the motor to get more
torque, but the gears would rather skip than lift the weight.

Has anyone out there successfully built this kind of scissor lift mechanism
in LEGO to lift a nontrivial weight? If so please reply here,
<http://www.brickpile.com/2006/03/03/scissor-lift-in-technic/#comments
comment on my blog> or email me any tips you may have. Thanks!

--Bill.

Hi Bill.

I came up with a design about a month ago.  It was never finished, but may be in
the future.

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=169187

The only problem is that the way I have it angled, the pistons have to push hard
at the beginning of the ascension.  However, this is the best way I could come
up with to maximize the relative travel of the pistons.  All you would have to
do is change the angle to get either a high rise with bad mechanical advantage
or a short rise with high mechanical advantage If you want me to finish it or
have any questions, let me know.

Nathan Bell

 

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