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(cross posted to my blog and BayLUG Mindstorms mailing list)
Have you ever tried building a scissor lift in LEGO? Im 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 arent 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.
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| "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
| | | | | | | | | | | | | | | | | | | "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
| | | | | | | | | | | | | | | | | | | | 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!
| | | | | | | | | | | | | | | | 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? Im 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 arent 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.
|
Havent 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 Ive 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
| | | | | | | | | | | | | | | | | | In lugnet.technic, Ross Crawford wrote:
|
Havent actually built one, but one other possibility may be to use string
rather than gearing directly.
|
On a winch? Thats an intriguing idea.
|
How many scissors are there in your lift? On the real ones Ive 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.
| | | | | | | | | | | | | | | | | | | | In lugnet.technic, William R. Ward wrote:
|
In lugnet.technic, Ross Crawford wrote:
|
Havent actually built one, but one other possibility may be to use string
rather than gearing directly.
|
On a winch? Thats 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 Ill work on that
later...
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| 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.
| | | | | | | | | | | | | | | | | | | "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.
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| |
| 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.
>
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| |
| "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/
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| |
| 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.
| | | | | | | | | | | | | | | | | | | | "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/
| | | | | | | | | | | | | | | | 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
| | | | | | | | | | | | | | | | | | 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 Ill stick with gears for now, as my pneumatics inventory is weak and I
think it would get too bulky. But Ill keep that in mind...
| | | | | | | | | | | | | | | |
| |
| > Have you ever tried building a scissor lift in LEGO? Im 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 arent 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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