Screw

MaeleeB
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Screw

Post by MaeleeB » December 7th, 2016, 7:56 am

I am unclear on the screw rules.It says that it needs to go two full rotations. Is that the actual screw that has to turn, or the object moving within the screw that has to go two full rotations?

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Re: Screw

Post by Unome » December 7th, 2016, 8:11 am

MaeleeB wrote:I am unclear on the screw rules.It says that it needs to go two full rotations. Is that the actual screw that has to turn, or the object moving within the screw that has to go two full rotations?
Are you planning a mechanism where the screw itself does not turn, rather the object it is attached to turns around it?

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Re: Screw

Post by kinghong1970 » December 7th, 2016, 9:21 am

my understanding is that for a fixed screw, the object rotating about the screw has to turn 2x

for a rotating screw, the screw itself needs to rotate 2x.

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Re: Screw

Post by MaeleeB » December 7th, 2016, 9:50 am

I was planning a stationary screw that doesn't move itself, but that a marble would move through it. But after reading the rules, it sounds like the screw itself needs to move, not just the marble. I'm confused.

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Re: Screw

Post by Unome » December 7th, 2016, 9:56 am

MaeleeB wrote:I was planning a stationary screw that doesn't move itself, but that a marble would move through it. But after reading the rules, it sounds like the screw itself needs to move, not just the marble. I'm confused.
That would be pretty difficult to defend using the rules' definition of a screw. I'd suggest using one of the options tha kinghong mentioned above (especially the first one, as that is probably easier to defend as legal to an event supervisor).

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Re: Screw

Post by MaeleeB » December 7th, 2016, 10:50 am

Unome wrote:
MaeleeB wrote:I was planning a stationary screw that doesn't move itself, but that a marble would move through it. But after reading the rules, it sounds like the screw itself needs to move, not just the marble. I'm confused.
That would be pretty difficult to defend using the rules' definition of a screw. I'd suggest using one of the options tha kinghong mentioned above (especially the first one, as that is probably easier to defend as legal to an event supervisor).


I'm sorry I'm new at this. When you say the "object rotating about the screw" you don't mean the marble in it? Can you recommend any resources to help me visualize what you are saying?

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Re: Screw

Post by SPP SciO » December 7th, 2016, 11:34 am

MaeleeB wrote: I'm sorry I'm new at this. When you say the "object rotating about the screw" you don't mean the marble in it? Can you recommend any resources to help me visualize what you are saying?
Rule 4.d.v. addresses screws - "must complete at least two full rotations"

If the screw isn't rotating, but a marble is traveling up it, really, you're using an inclined plane (and you wouldn't be able to claim it for points, because the marble would be rolling). And if the marble is traveling down the screw - well that's just a fancy spiral slide, and not a scoring simple machine. If the marble wasn't rolling, but you used a rotating vertical screw to move the marble up, that would be ok (as long as you get your two full rotations in).

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Re: Screw

Post by kinghong1970 » December 7th, 2016, 1:11 pm

MaeleeB wrote:
Unome wrote:
MaeleeB wrote:I was planning a stationary screw that doesn't move itself, but that a marble would move through it. But after reading the rules, it sounds like the screw itself needs to move, not just the marble. I'm confused.
That would be pretty difficult to defend using the rules' definition of a screw. I'd suggest using one of the options tha kinghong mentioned above (especially the first one, as that is probably easier to defend as legal to an event supervisor).


I'm sorry I'm new at this. When you say the "object rotating about the screw" you don't mean the marble in it? Can you recommend any resources to help me visualize what you are saying?
take a look at this...

Image

this is a simple archimedes screw using to pump "water" up and i think this is what you're talking about...

so this is a screw but... this example is better...

https://www.youtube.com/watch?v=MdWuXi9DQ9I

where you see when he rotates the handle on a larger diameter, it provides the rotation on the screw, and actually the pitch of the screw kinda acts as a wedge and transfers to a in or out motion with a certain amount of force.

sorry if confusing..., hope it helps.

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Re: Screw

Post by JZhang1 » December 7th, 2016, 6:51 pm

MaeleeB wrote:
Unome wrote:
MaeleeB wrote:I was planning a stationary screw that doesn't move itself, but that a marble would move through it. But after reading the rules, it sounds like the screw itself needs to move, not just the marble. I'm confused.
That would be pretty difficult to defend using the rules' definition of a screw. I'd suggest using one of the options tha kinghong mentioned above (especially the first one, as that is probably easier to defend as legal to an event supervisor).


I'm sorry I'm new at this. When you say the "object rotating about the screw" you don't mean the marble in it? Can you recommend any resources to help me visualize what you are saying?
I think having a marble inside a screw would be a bit impractical, My partner have a screw that's similar to the braking device on a scrambler. like this -https://www.youtube.com/watch?v=RJwFtkFSuJM But we have a weight falling to trigger the rotation.

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Re: Screw

Post by cookie75 » December 30th, 2016, 1:32 pm

MaeleeB wrote:
Unome wrote:
MaeleeB wrote:I was planning a stationary screw that doesn't move itself, but that a marble would move through it. But after reading the rules, it sounds like the screw itself needs to move, not just the marble. I'm confused.
That would be pretty difficult to defend using the rules' definition of a screw. I'd suggest using one of the options tha kinghong mentioned above (especially the first one, as that is probably easier to defend as legal to an event supervisor).


I'm sorry I'm new at this. When you say the "object rotating about the screw" you don't mean the marble in it? Can you recommend any resources to help me visualize what you are saying?
I do not understand the marble going THROUGH the screw. Do you mean the marble will go around the threads? Whatever your choice, how will the marble go through? The screw will have to turn at some point. A screw doesn't just turn or have something go around it, it has to go in a forward or backwards motion depending on the threads. like a real screw... This shows that the screw WILL indeed have to turn. 2 rounds in the minimum. Hope this helps...THX

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