Subject:
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Re: JCB JS220 Excavator
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 25 Nov 2003 19:15:44 GMT
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Viewed:
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3892 times
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In lugnet.technic, Tobbe Arnesson wrote:
> The flaws of the model is mostly in the limits of the
> brick, such as the somewhat digital behaviour of the pneumatic system. Still,
> the model is so well tuned with speed vs. performance that it can be driven
> smoothly - even under load!
>
> Watching the "dig a hole"-movie is an eye-opener. Can a MOC out of LEGO >really
> be *that* realistic!? Sure, the person that drives it in the movie hits the
> sticks in the wrong way a few times - still it proves that it can almost be
> driven as smooth as hydraulics. Some achievment!
Hi Tobbe
The functions aren't 'digital like", I know because I too have a digger just
like Jennifer's. You can move the sticks slightly and get a proportional output.
I built my model to test the dual axis control mechanism I came up with that Jen
name-checks on her site (thanks Jen).
Even when operating the arm in the down direction you can still regulate it's
speed if you have a deft touch on the sticks.
I watched Jen's digging vid and I think all she needs is a bit more practice. It
can be tricky as I know when I tried demonstrating the device at a Legofest.
And I don't suppose she has too many opportunities to take the model to the
beach.
I think when digging you should dig with the elbow and use the bucket's crowd
feature last.
My prediction for the future is maybe using different source's of air for
different functions. Jen's bucket crowds very quickly because it's powered at
the same pressure as that used to raise the 4 rams of the arm. If you had a
second supply at quarter pressure the two functions would be more proportional
to each other.
Steve
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Message has 3 Replies:
 | | Re: JCB JS220 Excavator
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| (...) I'd agree with this, it is possible to control the pneumatic valves so that more or less air gets through them. Rather than the problem with pneumatics being of digital in nature, to my mind the biggest problem is their elastic or springy (...) (20 years ago, 25-Nov-03, to lugnet.technic)
| | | Re: JCB JS220 Excavator
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| (...) Yeah, I know, I know. But "digital like" was a term that I figured most people would understand, and perhaps even apriciate if your initials are K.C. :) Then enters the "ooh, I can beat this foreign kid in the language game"-brat... :P Heck, (...) (20 years ago, 26-Nov-03, to lugnet.technic)
| | | Re: JCB JS220 Excavator
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| (...) A comment on how you might be able to control the speed of pneumatics is to add an orifice to both of the line of the cylinder. This would regulate the amount and speed of the air entering and leaving the cylinder. Hope this gives you some (...) (20 years ago, 12-Dec-03, to lugnet.technic)
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Message is in Reply To:
| | Re: JCB JS220 Excavator
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| (...) Despite the fact that you have amazed me to a great extent at no less then five different occations - I'm stunned! This exceeds anything I've ever seen done in the field of Technic/Modelteam previously - really! It pushes the envelope of LEGO (...) (20 years ago, 25-Nov-03, to lugnet.technic)
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