Subject:
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First attempt at a feed hopper. (Long)
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 17 Feb 2005 10:54:56 GMT
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Reply-To:
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Geoffrey Hyde <GDOTHYDE@BIGPONDDOTNETDOspamlessTAU>
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Viewed:
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1309 times
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Well, here goes nothing. My first attempt at making a feed hopper that
feeds basketballs:
Folder once public, deep links are included below:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=117590
The inside of the hopper assembly, showing the chain and technic tread link
that drives the basketballs out the front. It's rather prone to jamming,
with basketballs just sitting there and jostling each other - I need to work
on that to try and improve it somehow.
The black brick in the first pic (yes I know it reads 0002 but the real
first pic went MIA) below is a small assembly of plates and bricks mounted
vertically with a grey 2x3 roof piece at the bottom, this was needed to stop
the basketballs from getting onto the rear driven gear the chain sits on,
and just sitting there rolling along.
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0002.jpg
In this next pic we get an idea of the drive mechanism. More to follow on
that subject.
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0003.jpg
This is a view showing part of the two 16 stud technic beams I mounted the
motor drive mechanism on. Note that it's upside-down, and "floating"
loosely on a few 1x2 plates which raise it up just enough off the baseplate
so the large 40t gear doesn't hit the studs and make an extra large grinding
noise. I'm currently looking for a better way to have the drivetrain start
off - more on that later. This drive mechanism is currently the result of
90% error and 10% trial! *grins* If anyone's got a good general-purpose
drive mechanism on the web somewhere please let me know, so I can try to
improve mine!
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0004.jpg
Here we get an idea of the drivetrain gearing ratio. Along with dscf0003,
notice I put gears on both sides of the two beams to try and get everything
into as little space as possible. Notation for drivetrain which I show
below, for reference, is as follows: dash "-" means it drives the next
gear, right angle bracket ">" means it drives an axle holding a gear on it
that drives another gear.
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0005.jpg
8t-40t-24t>8t-24t>8t-24t>worm gear - not currently visible is an excellent
one-way drive assembly from Rob Antinoshen, described and pictured here -
thanks Rob!:
http://www.baumfamily.org/lego/creations/dirtrans/
Visible in the dscf0005 pic is the idler gearwheel sitting one of the output
shafts that enables the mechanism to be driven either way by a motor and not
be able to go in reverse. It's surprisingly effective and uses the
technique of sliding worm gears to achieve this remarkable reversing action.
The only problem with it is the way it is built with the technic parts which
hold the gear above the two 8t gears it didn't quite line up with any
single-holed bricks I had, so I had to improvise and mount the gear
reduction rack so it drives it through a series of gears. I'm hoping to
improve this a lot.
The gear tower itself is shown here in dscf0006 below which raises the
output up and across so as to drive the chain visible in dscf0002. You can
just make out the idler gearwheel which is sitting behind one of the 12t
gears making up this section. No gear reduction takes place at this point,
in fact maybe I should redesign the drive reduction mechanism so it doesn't
drive things so slowly, however, I'm still trying to find a better gear
reduction assembly with which to do it.
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0006.jpg
In this next pic we see my hand resting near the output stage that this
hopper currently feeds (or more correctly drops) into. Eventually, this
will be part of a contraption that actually does something with the balls.
The odd ball might escape from this catchment area although I don't expect
it to be much of a problem once I design the next stage of the contraption.
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0007.jpg
In this pic we see the front end of the feed hopper output and a view
showing the slight incline in the chain so basketballs don't automatically
try to roll out through natural momentum. I was rather hoping they wouldn't
drop so freely, I had to do a fair bit of improvising to get them to stay in
the hopper until pushed out by the chain link tread. As mentioned
previously, this is notorious for jamming up and resulting in basketballs
just sitting there rolling up and down. More improvement will definitely be
needed in this area.
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0008.jpg
This view shows the 1x2 plates and bricks the motor drive train is sitting
on. Not very effective but it stops movement and I don't have to make it
physically strong so I left it at that for the moment. I would like to
improve the gear the motor is driving, though, as I wanted it to drive a 24t
gear instead of a 40t gear. This arrangement was the easiest mounting I
could come up with so far, note that the 8t gear on the motor meshes quite
well with the 40t gear it drives although it does make one heck of a racket!
*grins*
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0009.jpg
This last pic shows, clearly, the drive train itself, as described above in
dscf0003/dscf0004. Note that I would like to make a much improved reduction
gearbox, preferably with the motor sitting on top of a tower, and driving
gears around inside until it gets down to the worm gear one-way drive. I
chose to use the current implementation in case I ever needed the motor to
be reversible to drive other part of the mechanism, I could if I wanted,
make a reversing loop with the Technic Control Center II from 8485 to make
it simultaneously drop the basketballs and drive a little hoist mechanism,
either for bringing new balls into the feed hopper, or for other things,
like action accessories that sit there and look pretty.
http://www.brickshelf.com/gallery/ghyde/GBC-hopper/dscf0010.jpg
I'm looking forward to everyone's comments, and I would like to thank Tim of
UBL for a lot of the bricks I've purchased so far! They have been most
helpful in helping me procure a much-needed supply of used bricks, which
I've added to my own stocks of bricks.
I have also purchased some Technic Link Tread from Praetorian (Hope I
spelled your name right!) and some general brick supplies from other people
as well! I'm interested in trades for large quantities of general-purpose
bricks, such as 1xn (particularly 1x3, quantitity 50+, and 2xn etc. I've
got a store on bricklink, Far North Bricks, which people could order from as
part of a trade deal, if they wanted any of my stock from there - although,
please be sure to contact me via my contact form, *before ordering* so I can
make sure your offer is what I'm looking for.
Store link is here - contact me through contact form *before ordering* if
trading, please:
http://www.bricklink.com/store.asp?p=ghyde
Cheers ...
Geoffrey Hyde
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Message has 1 Reply:
 | | Re: First attempt at a feed hopper. (Long)
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| On Thu, February 17, 2005 5:54 am, Geoffrey Hyde said: (...) Geoffrey, This looks like a nice start. I suspect it will get more refined as you go. Looking at the drive train, it looks like the final speed is about .3 rotations per second. If you (...) (20 years ago, 17-Feb-05, to lugnet.robotics)
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