Subject:
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Re: Update on 3 digit LEGO calculator (Babbage Difference Engine)
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Newsgroups:
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lugnet.build
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Date:
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Thu, 9 Feb 2006 06:44:20 GMT
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Viewed:
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3334 times
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In lugnet.announce.moc, Andrew Carol wrote:
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Howdy.
I’ve been working on my 3 digit LEGO mechanical calculator (more properly the
Babbage Style LEGO Difference Engine)
The machine works quite well, but others have asked how to build their own and
I realize what operated well in development would be hard to convey to others
because a lot is in my head and there was a lot of “alignment” tricks used
when bringing the modules together.
The current machine is at http://acarol.woz.org
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Andy, I am blown away!!
I have been playing around building bits and pieces
of a LEGO Difference Engine for some time.
Tim has remarked on this, see:
http://news.lugnet.com/org/us/texlug/?n=455
I was also aware of:
http://goldfish.ikaruga.co.uk/difference.html
and
http://www.clrc.ac.uk/Activity/MAD;SECTION=8574;
But your work is amazing!
Are you using digit retention? (ie. are spings holding the digits in place)
are you using 40 to 16 gear mesh to get 90 degree digit retention.
How are you disconnecting the rotation of the adding digit drum
when it passes 0? A clutch? or...?
Do you have carry bit storage? a bi-stable (flip-flop)?
Or are you adding the carry in through a differential?
I don’t see any?
Do you have 2 or 4 or more phases? Maybe with just 2 digit columns...
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With that in mind, I have made many improvements this weekend which will make
it easier for others to build one as well as to break down/reassemble modules.
Improvements made (photos by weekend):
1 - Alignment pegs on carry gears.
Previously aligning the carry gears when connecting digit columns took a good
eye. Now, just rotate the carry gears until the pegs align and connect the
columns.
2 - Keyed digit wheels.
Previously there was a rule used when connecting the output of a lower adder
to the adder above through a digit wheel. (There is a 60 degree rotation
between lower and upper adders). The rule was simple and only took a moment
for each digit but was a pain to have to think about.
Now I’ve “keyed” the digit wheel so there is only one way the two can be
connected.
3 - Adder rotor “quick” removal!
The hardest part to install in the current design is the adder rotor. Once
in, it requires quite a bit of partial disassembly to get it out. I don’t
remove one lightly. It also complicates testing because the rotor has to go
in so early the power drive system is harder to get smooth.
I’ve found a way to have a slide/lock which will hold it in place. Turning
the lock and raising a liftarm used as a slip-ring allows the rotor to be
easily added or removed.
The new rotor has slightly more wobble than the previous one, but I don’t
think this will matter. More testing will tell for sure.
I hope to have new pictures and details on the web page sometime in the next
week.
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Please do so!!
Oh yes, I would be very interrested in seeing any new pics!
If you could explain your digit columns.
BUT AGAIN THIS IS GREAT!!!!!!
kurt
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Cheers!
--- Andy http://acarol.woz.org
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