Sand Loading Device

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John Richardsim
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Re: Sand Loading Device

Postby John Richardsim » Mon Sep 08, 2014 11:53 pm

iwonder wrote:Honestly the only places I've seen an auto loader used were at my schools invite and I think one other large invitational. Our state contest doesn't use one, but I'm pretty sure nationals has one every year.

Correct me if I'm wrong, but I'm pretty sure boomilever was loaded by hand at 2013 nationals. Not sure if it was at 2014 nationals though...
If possible, you should definitely consider loading a bridge by hand prior to any competition that may have you load by hand (especially if they've never used sand loading devices in the past). This past season, after states, my team's boomilever competitors practiced loading by hand on several boomilevers (including one I built; it didn't fare out too well).
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Re: Sand Loading Device

Postby iwonder » Tue Sep 09, 2014 1:42 am

calgoddard wrote:However, I have seen students, again intentionally or unintentionally, have the chain between the loading block and the bucket partially hung up on, or frictionally engaged with the loader spout in some fashion. This became evident at a State competition when a number of structures in a row carried the full load when clearly that was not physically possible by casual inspection of the size and design of the balsa structures themselves.


What style of loader/chain was being used in that case? There aren't a lot of styles that I can imagine being able to catch on the loader and support 15kg (I don't think any chain would be elastic enough to 'split' the load between the bucket and the loader-support)

Oh, and yeah that year might not've loaded by machine. That line came from my coach (as reasoning to have bought a very expensive autoloader many years ago).
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Re: Sand Loading Device

Postby hren science » Wed Sep 10, 2014 11:18 pm

forgive me but im new to scioly. so do you have to make a sand loading device?

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bernard
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Re: Sand Loading Device

Postby bernard » Thu Sep 11, 2014 12:26 am

hren science wrote:forgive me but im new to scioly. so do you have to make a sand loading device?

No, regional, state, and national tournaments provide any testing apparatuses needed to run an event. If your school hosts its own invitational, it may need to provide the loading device/testing apparatuses.
Last edited by bernard on Sun Sep 14, 2014 12:16 am, edited 1 time in total.

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Re: Sand Loading Device

Postby calgoddard » Thu Sep 11, 2014 3:09 pm

Quote: "What style of loader/chain was being used in that case?"

The state competition I referenced was several years ago. No pictures or video were allowed, except of your own team. I did not take any pictures of our teams' tower mounted on the sand loading device in question. I do not currently have any access to any such pictures.

To the best of my recollection, the sand loader that was used had a configuration similar to the commercial one identified above. It had a lever that was moved forward to dispense the sand, and the sand automatically stopped dispensing once the structure collapsed. The problem was that the chain from the loading block draped over some portion of the spout and/or gate mechanism, resulting in the loader carrying the weight of the bucket and sand deposited therein, at least for a major portion of the loading sequence during the competition loading of at least some of the balsa structures, including, apparently, the announced winner.

I am not inferring that the lever actuated sand loader in question was improperly designed or built, just that when using such a sand loader, care needs to be taken to ensure that the loading block, bucket and chain are correctly set up for each balsa structure that is tested.

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Re: Sand Loading Device

Postby iwonder » Thu Sep 11, 2014 3:11 pm

I didn't think you were talking about it being badly built, but it does sound like a procedural problem with the loading, I just couldn't picture how a chain would get caught on one like that commercial loader posted, that's all.
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Re: Sand Loading Device

Postby dholdgreve » Fri Sep 12, 2014 12:57 pm

Keep in mind that this year the time has been reduced from 10 minutes to 8 minutes, and it has been clarified to include set-up time, where in the past it was applied inconsistently as either just the loading part, or the entire set up and loading. This may trigger more teams and event coordinators to lean toward a dispenser, as they can deliver the full payload in under 2 minutes, allowing much more time for proper set-up protocols. We looked at a number of ways to make the sand valve automatically snap shut when the structure failed, but there were just too many unknowns, so we resorted to a supervisor release using an archery release... when the supervisor pulls his string, the release opens, separating the knife valve from the lever, and allows the spring tensioned knife valve to snap shut like a guillotine, shutting off the flow of sand. Not counting labor or sand, I believe our unit cost about $80 in materials to build. Not nearly as pretty as some of the one available commercially, but just as functional.
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