Screw Task

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Re: Screw Task

Postby MyWorldRules » November 25th, 2018, 8:20 am

I tried attaching a rope to the screw and then pulling the rope to rotate the screw. But I tested that and the screw doesn't rotate.

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Re: Screw Task

Postby killer225whale » November 25th, 2018, 10:13 am

MyWorldRules wrote:I tried attaching a rope to the screw and then pulling the rope to rotate the screw. But I tested that and the screw doesn't rotate.

Sounds like you have too much friction in your system? Trying to rotate a screw in a threaded block (or a nut) probably has too much friction involved; I'd probably do it by using a partially-threaded machine bolt; the smooth part would be in some ball bearings (or just resting in two V mounts, with the string wrapped around the smooth part.

String drops, screw rotates, and have a wingnut or hex nut that moves along the threaded part of the bolt. If there's still too much friction, you can probably try oiling/greasing where the bolt contacts the mounts and the nut, or also wrapping tape or something around where the string wraps around the bolt to increase the diameter and the torque.

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Re: Screw Task

Postby Caesar » November 29th, 2018, 1:06 pm

When I was in div B I did this task by using a flame to break a string holding a mass. I think that design could be easily combined with the string task.
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Re: Screw Task

Postby TheSquaad » November 29th, 2018, 4:32 pm

cheese wrote:
honorstoise wrote:If you attach an object to the screw does it count as a separate object or part of the screw

I would consider it to be part of the screw.


I wouldn’t. The event description never specified that the moved object has to be removable or unattached.

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Re: Screw Task

Postby C8H10N4O2! » December 4th, 2018, 1:47 pm

would i be allowed to have a screw task that is actually a pulley (but only 1 wheel), which is pulled by the force of gravity (a mass), and moves another mass or so 2 cm upwards? i just want to know if this technically works (i am converting rotational force into linear, would it just be a matter of wording it properly?)

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Re: Screw Task

Postby Unome » December 4th, 2018, 3:12 pm

C8H10N4O2! wrote:would i be allowed to have a screw task that is actually a pulley (but only 1 wheel), which is pulled by the force of gravity (a mass), and moves another mass or so 2 cm upwards? i just want to know if this technically works (i am converting rotational force into linear, would it just be a matter of wording it properly?)

I would say this doesn't fit the definition of "operating as a screw" in rule 4.b.ix.
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Re: Screw Task

Postby Flavorflav » December 9th, 2018, 4:59 pm

TheSquaad wrote:
cheese wrote:
honorstoise wrote:If you attach an object to the screw does it count as a separate object or part of the screw

I would consider it to be part of the screw.


I wouldn’t. The event description never specified that the moved object has to be removable or unattached.


I would consider an attached object to be a part of the screw if and only if it rotates with the screw.

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Re: Screw Task

Postby Flavorflav » December 9th, 2018, 5:01 pm

Wabbit wrote:
nicholasmaurer wrote:
Wabbit wrote:Do we think that the screw must be in contact with the object it is moving for the whole time? For example, if the screw was moved horizontally only about one centimeter, but made contact with a ball, hitting it and causing it to roll for an additional one or two centimeters, would that satisfy the rules?


The descriptions states that the screw must achieve two tasks: operating as a screw AND moving an object 2cm. I would argue if you bump a ball and simply allow it to roll, gravity is moving the ball for most of that 2cm, not the screw.


I wasn't thinking about using gravity or a ramp. If a screw with wide enough threads is turned fast enough it could hit a small ball and get it to roll across a flat surface. In this case, the screw would be providing all of the energy that the ball needs to move, but the screw would not need to move the full 2 cm itself.

You would have to convince me that the surface was indeed level, which might not be easy to do. It would be safer to make it incline slightly upward, so that it is clear that there is no gravity-assist.

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Re: Screw Task

Postby Unome » December 9th, 2018, 5:33 pm

Flavorflav wrote:
Wabbit wrote:
nicholasmaurer wrote:
The descriptions states that the screw must achieve two tasks: operating as a screw AND moving an object 2cm. I would argue if you bump a ball and simply allow it to roll, gravity is moving the ball for most of that 2cm, not the screw.


I wasn't thinking about using gravity or a ramp. If a screw with wide enough threads is turned fast enough it could hit a small ball and get it to roll across a flat surface. In this case, the screw would be providing all of the energy that the ball needs to move, but the screw would not need to move the full 2 cm itself.

You would have to convince me that the surface was indeed level, which might not be easy to do. It would be safer to make it incline slightly upward, so that it is clear that there is no gravity-assist.

Also consider that you need to take into account the possibility of a tilted table, if a tournament forces you to use a table (or a tilted floor, for that matter)
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Re: Screw Task

Postby TheSquaad » December 9th, 2018, 8:01 pm

Flavorflav wrote:
TheSquaad wrote:
cheese wrote:I would consider it to be part of the screw.


I wouldn’t. The event description never specified that the moved object has to be removable or unattached.


I would consider an attached object to be a part of the screw if and only if it rotates with the screw.


Imma post an faq about this. In my mind there should be no issue as long as the piece is removable, but I feel like the nats board should clarify this


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