LEGO TECHNIC : 308


Technic / 308

Any ideas on how to do this with Technic? —Paul Davidson

Hi, I'm considering an Adventurers-themed Lego project that involves a structure that, when triggered, can sink into the "ground" (as on The Mummy). My general idea is that at four locations (two on each of opposite sides), the part of the structure (...) (25 years ago, 30-Nov-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Kevin Maynes

(...) Well, I know you don't want to use motors....but.... :) I just picked up a 3038 "Spider Slayer" set, and the motor therein is actually quite weak - put a wheel on the axle and it spins real easy. If you built your gear mechanism then hooked (...) (25 years ago, 30-Nov-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Steve Bliss

(...) Hmm. Use a pair of pulleys, one attached to the same axle as the gear being turned against the rack. The other pulley should be attached to the same frame as the first, so they move together as the building sinks. This second pulley should (...) (25 years ago, 30-Nov-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Fredrik Glöckner

(...) You can use an pendulum clock to time the mechanism so that it sinks at a constant speed. No, I'm not kidding! Take a look at Leo Dorst's LEGO clock: (URL) only need the pendulum, escapement and cogwheel part. The idea would be to use the (...) (25 years ago, 30-Nov-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Paul Davidson

I've received some very good responses here. Jacob Andersen's worm gear idea is what I would do if I were to use a motor, but since gravity already provides energy for the system, a good engineering solution would not use an additional motor. Plus, (...) (25 years ago, 30-Nov-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Bruce Schlickbernd

(...) Counter-weight through a pulley or gear system? A lessening counter-weight (classic sand displacement)? Bruce (25 years ago, 30-Nov-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Paul Davidson

A counterweight doesn't change the speed at which something falls, does it? It may reduce the apparent weight of the main structure, but objects of different weights fall equally fast. -- Paul Davidson, aka Tinman www.theforce.net | Your Daily Dose (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Peter Callaway

(...) Not entirely true. Your thinking of the "what falls faster, a tonne of lead or a tonne of feathers" question (or - "what's heavier, a tonne of lead or a tonne of feathers") which is actually more complicated than it seems. The thing with a (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Paul Davidson

I see. I understand what you're saying. The main thing I'm looking for in this case, though, is a constant downward speed which does not accelerate. Your ideas are interesting though, I will probably incorporate them into future projects (a working (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Peter Callaway

(...) That's where the friction in the pulley comes into play. Your system will need to accelerate initially to attain some sort of velocity. The friction will eventually (and pretty quickly if you fine-tune it right) counter act the acceleration, (...) (25 years ago, 2-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Fredrik Glöckner

(...) It wasn't me, 'twas Steve Bliss. (...) This sounds like a very interesting project indeed! You should report back if you succeed with this. You need to connect the weight of the base to the pendulum. How are you going to do that? You can have (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Paul Davidson

I'm thinking of having the gears on the moveable structure itself connect to the pendulum...I'm not sure yet how much friction there will be, I may need to use a lot of lego on the structure to make it heavier. -- Paul Davidson, aka Tinman (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Jacob Sparre Andersen

Paul Davidson: [ Structure sinking into the ground at constant speed ] I would see if I could do something with some worm screws (LDraw part 4716), a micro motor (LDraw part 2986), and maybe some gear racks (LDraw part 3743). The worm screws will (...) (25 years ago, 30-Nov-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —David Paule

(...) That strange, thick, white gear in the RIS slips with drag that appears proportional to the rotation rate, so it's a dampener, which is what you want. Dave Paule (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Fredrik Glöckner

(...) I may very well be wrong, but I don't think this will give the desired effect. The friction inside the gear is quite high when there is no motion, which may be a problem when the mechanism is triggered. And what's more, I don't think it will (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

RE: Any ideas on how to do this with Technic? —Ralph Hempel

If you want to vary the rate at which an object of constant weight moves, why not use a mechanism like an old postal scale. No, not the kind that shoots you when you look at it sideways... It involves a pendulum mounted so that when the object is at (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Paul Davidson

That's a good solution as well. It might be harder to make the descent *really* slow, though, as is possible with a clock-style pendulum. -- Paul Davidson, aka Tinman www.theforce.net | Your Daily Dose of Star Wars www.filmforce.net | Your Daily (...) (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Mike McFarlane

Hi (...) One of us is going daft and I suspect me. Which strange, thick white gear in the RIS??? Or is this in the 1.5 version?? Mike (25 years ago, 1-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —David Paule

(...) want. (...) No daftness at all - a good guess. I didn't know it wasn't in version 1.0. It's in the 1.5 version. I haven't found a use for it yet, although it is on p. 59 of the 1.5 Constructopedia and on their parts page inside the back cover. (...) (25 years ago, 2-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Patrick C. Emerson

(...) Actually...I think that is supposed to be a clutch. It also comes in the new 9V motor set 8735. Pat (25 years ago, 2-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Fredrik Glöckner

(...) I don't think clutch is the correct term. The white 24t gear cog is normally used to protect the motor from stress. If you use the white gear in a gear train, it will slip if the load becomes too high, which is better than having the motor (...) (25 years ago, 2-Dec-99, to lugnet.technic, lugnet.adventurers)

Re: Any ideas on how to do this with Technic? —Kevin Maynes

(...) I don't know what the big 'L' calls it, but I think it's a Slipper Clutch. They're used all over the place in r/c race cars, to protect the drivetrain, both the motor and the gears/belts, from the abuse of a heavy throttle finger and/or rough (...) (25 years ago, 2-Dec-99, to lugnet.technic, lugnet.adventurers)