Scioly.org

Keep in mind that when you're designing these things on such short notice, most of the time a string that's just looped over a nail is good enough, so the small amount of stretch in a string is nearly inconsequential. Also if you can find it fly backing makes very good string to use. You can buy 40 or even 80 pound test line that's something like 1/32" diameter and I've never seen it stretch.

fly backing makes very good string to use. You can buy 40 or even 80 pound test line that's something like 1/32" diameter and I've never seen it stretch.

Yes, I was thinking that fishing line is the right stuff to use. Available off the shelf. And it's very low friction. 3 dowels will suffice for a slick surface instead of buying and mounting pulleys. I'll see what the hardware store has for pulleys, perhaps they have one that locks or something.

* I got pulleys from Home Dept. Got mason line , 10 lb rated.
* Wheels are a problem but working on it. servocity parts - some good, some not. Wheels themselves are nice. Ball bearing hubs + 6/32 screws + nylock nuts = nice. 1/2" channel, bad idea: not enough travel for wing nut. 28 tpi threaded rod: nice idea, but good luck finding 28 tpi wing nuts. Got 20 tpi nut and 20 tpi threaded rod. Now getting the wheel attached such that the axle rotates...well, that isn't a good thing to do with ball bearing hubs. Worked up something to jam the wheel and make the axle spin

The major issue I don't understand right now is the mass. Rules say nothing that was not in contact with ground at start can hit ground. OK, so if I have a thin platform attached to the back of my tower as a landing pad which itself in turn rests on the ground is that "hitting the ground"? I have a corner brace tied onto the string, that's not going to through the pulley but it might be too long....I rather hit the landing pad....

dhudes wrote:The major issue I don't understand right now is the mass. Rules say nothing that was not in contact with ground at start can hit ground. OK, so if I have a thin platform attached to the back of my tower as a landing pad which itself in turn rests on the ground is that "hitting the ground"?

That's exactly what I did last year, I think it might also work if you tie a knot in the string so it stops on the top pulley, just short of the ground. I'm not sure if there were any clarifications dissuading my method (I graduated last year)

Yeah, last year at competitions I literally just laid a piece of wood on the ground under where my mass dropped. I didn't even have time to attach it to anything XD. But didn't get DQ'd for it . Admittedly it took the fall of the nearly 2 kg mass I used, so I guess that works (and no scratches on the floor).

Last year at NJ states, teams that avoided the problem just used a sheet of paper at the suggestion of the event supervisor.

nxtscholar wrote:Last year at NJ states, teams that avoided the problem just used a sheet of paper at the suggestion of the event supervisor.

The thing is, this won't always work this year. The mass or whatever you are trying to avoid hitting the floor might still damage the floor or venue through the paper...

First, I'd like to point out the only relevant rule I see is rule 2h, where it states "the falling mass must not come in contact with the floor at any time." Unless I missed something, the rules don't explicitly state that the mass shouldn't damage the floors. I know the intent of the rule was to prevent damage to the floors (and obviously, I know that paper hardly offers protection) but my point is it's not specifically mentioned.

Now why do I bring that up?

I don't think you got my connotation. I'll apologize for not making it clear. Last year, I brought up the same point and made no effort to hide my disdain that the event supervisor straight out assisted teams that would have OTHERWISE BEEN TIERED. How is that fair to the students like me who evidently wasted time to set up measures to make sure the mass wouldn't touch the floor and damage it? Some teams even cut off a crucial last 0.1 m of falling distance just to build something to catch the mass - and it was all in vain when apparently, we could have just used a simple sheet of paper to "catch" the mass.

I sincerely believe that because the condition of the floor was not explicitly mentioned in the rules , the E/S let that one go.

EDIT: Sorry, I missed 2i

nxtscholar wrote:First, I'd like to point out the only relevant rule I see is rule 2h, where it states "the falling mass must not come in contact with the floor at any time." Unless I missed something, the rules don't explicitly state that the mass shouldn't damage the floors. I know the intent of the rule was to prevent damage to the floors (and obviously, I know that paper hardly offers protection) but my point is it's not specifically mentioned.

Now why do I bring that up?

I don't think you got my connotation. I'll apologize for not making it clear. Last year, I brought up the same point and made no effort to hide my disdain that the event supervisor straight out assisted teams that would have OTHERWISE BEEN TIERED. How is that fair to the students like me who evidently wasted time to set up measures to make sure the mass wouldn't touch the floor and damage it? Some teams even cut off a crucial last 0.1 m of falling distance just to build something to catch the mass - and it was all in vain when apparently, we could have just used a simple sheet of paper to "catch" the mass.

I sincerely believe that because the condition of the floor was not explicitly mentioned in the rules , the E/S let that one go.

Also keep in mind that rule 2j says the scrambler can't damage the track this year.

Last year I just put down a 3/16" sheet of plywood (that's 0.5% of the fall) and I never had to worry about denting the floor. But I do know of some other people on this forum who put down poster board or just paper and were fine. It all depends on what your mass is and how it falls.

I have a question about rule 2c. It says, "Any part of the Scrambler whose gravitational potential energy decreases and provides energy to propel the ETV is considered to be part of the falling mass...the Scrambler must be impounded with the mass completely detached"
Does this mean that any string that decreases in potential energy must be detached at impound? Or is that considered to be of negligible mass?

Also, if I start with a notebook propped up on a piece of wood, and then allow the notebook to fall completely on the floor, would that be against rule 2h?