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Tech question for us: Any body know what an Anti-Backlash gear is? If Lego
made one, we would all have super precise Robots and mechanisisms! BERG
carries them... Anybody know what I'm talking about?
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Isnt that the same as the white clutch gear. Here is a link to it:
http://w3.one.net/~hughesj/technica/registry/gear/gear_3.html
Ram
Eric Sophie wrote:
> Tech question for us: Any body know what an Anti-Backlash gear is? If Lego
> made one, we would all have super precise Robots and mechanisisms! BERG
> carries them... Anybody know what I'm talking about?
>
>
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Eric Sophie wrote:
> Tech question for us: Any body know what an Anti-Backlash gear is? If Lego
> made one, we would all have super precise Robots and mechanisisms! BERG
> carries them... Anybody know what I'm talking about?
I have done quite a lot of experimentation to limit backlash in certain
situations.
First of all, it is quite easy to make little shims from the yellow plastic
material
the parts are seperated into in new sets. I make ones with 0.2" holes in
the center
0.3" outer diameter. These can be placed behind bevel gears to improve the mesh
and get less backlash.
In the case of the rectagular blocks which are worm gear boxes, you can
trap one
of these washers at one end of the worm. This reduces slop in the worm position
and really improves the resultant output shaft firmness.
In simple mechanisms like scanning devices, try loading the drive train
with a rubber
band. This will keep all the teeth meshing biased and increase the accuracy at
the expense of maximum torque of course.
JB
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Interesting point about the rubber bands vs the resultant torque loss, it is
true that the opposing forces on the gears along with the "rubber pull" will
tender them to one direction or another in concert...
However,...and I say this kindly and jokingly, ....Cheater!!!
You experimented (cheated) with washers of a sort, gaaa..
Pardon my Lego purism. I too have tried to use series 1 bevel gears in
different ways ,, but it never made up for the fact that TLC's worm gear is
short! in fact when I was able to get a measure of "shimming" the resultant
distance of the axle cause a bowing effect when a heavy load was placed on
the drive gear and the connection would skip....
Make that a longer Worm gear and an anti-backlash gear to go Please Thank
you TLC
Eric Sophie
In lugnet.robotics, John Barnes writes:
> Eric Sophie wrote:
>
> > Tech question for us: Any body know what an Anti-Backlash gear is? If Lego
> > made one, we would all have super precise Robots and mechanisisms! BERG
> > carries them... Anybody know what I'm talking about?
>
> I have done quite a lot of experimentation to limit backlash in certain
> situations.
> First of all, it is quite easy to make little shims from the yellow plastic
> material
> the parts are seperated into in new sets. I make ones with 0.2" holes in
> the center
> 0.3" outer diameter. These can be placed behind bevel gears to improve the mesh
> and get less backlash.
>
> In the case of the rectagular blocks which are worm gear boxes, you can
> trap one
> of these washers at one end of the worm. This reduces slop in the worm position
> and really improves the resultant output shaft firmness.
>
> In simple mechanisms like scanning devices, try loading the drive train
> with a rubber
> band. This will keep all the teeth meshing biased and increase the accuracy at
> the expense of maximum torque of course.
>
> JB
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>>>>>>
However,...and I say this kindly and jokingly, ....Cheater!!!
You experimented (cheated) with washers of a sort, gaaa..
<<<<<<
Hey! real engineering uses shims (not washers ;)
And I can honestly put my hand on my heart and say everything
in this model came out of that official Lego box! Ok, so I used some
of the packaging :)
JB
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Whoa, I gotta think about this one for awhile.....
In lugnet.robotics, Robert Fay writes:
> The closest thing to an anti-backlash gear is the Conical gear (a misnomer).
> It can be used to load a gear train. I have used this in a design by Iain
> Hendry.
> http://bobfay.users5.50megs.com/newmill.htm
>
> I have tried using a second motor in the gear train with a slight reverse
> current. This pretty bulky.
>
> I think the gear you want is a sandwich of two gears that are spring loaded
> so the teeth oppose each other. This would work in a small gear train.
>
> There is another example of the conical gear at the end of this page.
> http://bobfay.users5.50megs.com/speedy.htm
> --
> Bob Fay
> rfay@we.mediaone.net
>
> http://bobfay.users5.50megs.com/index.html
> http://www.geocities.com/Heartland/Bluffs/7900/
> "Eric Sophie" <Legomaster@gobi.com> wrote in message
> news:GB7x2F.J0G@lugnet.com...
> > Tech question for us: Any body know what an Anti-Backlash gear is?
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Ram Meenakshisundaram wrote:
> Isnt that the same as the white clutch gear. Here is a link to it:
> http://w3.one.net/~hughesj/technica/registry/gear/gear_3.html
Maybe I'm just clueless, but I've yet to figure out what
one would do with this. The Lego Mindstorms booklet doesn't
explain it at all. (My host laptop computer runs Linux, and
so if it is explained in the nifty multimedia CD-ROM that
came with Mindstorms, I've missed it.)
It took me weeks to finally figure out what the differential
gear really was, and I'm still trying to figure out the best
way top operate the brick seperator. Didn't even know what it
was until I saw it named in a catalog.
> Ram
Chris - Xenon
--
Chris Hanson | Xenon@3DNature.com | I've got friends in low latitudes!
New WCS 5 Demo Version! http://www.3DNature.com/demo/
"There is no Truth. There is only Perception. To Perceive is to Exist." - Xen
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Ha Ha that's great...ok buddy, thanks... Eric,
- I still have got to ponder these pix for awhile!
In lugnet.robotics, John Barnes writes:
>
> However,...and I say this kindly and jokingly, ....Cheater!!!
> You experimented (cheated) with washers of a sort, gaaa..
> <<<<<<
>
> Hey! real engineering uses shims (not washers ;)
>
> And I can honestly put my hand on my heart and say everything
> in this model came out of that official Lego box! Ok, so I used some
> of the packaging :)
>
> JB
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It's not so much the "conical" gear that takes the backlash out of the setup
that Bob Fay provided links to, but the ability to use the technic axles as
torsion springs and keep the gear teeth in the train loaded at all times.
That particular gear does make it much easier to do this trick with out
breaking LEGO(R) parts though : )
HTH,
Xanthra47
"Bob Fay" <rfay@we.mediaone.net> wrote in message
news:GB7y67.LCK@lugnet.com...
> The closest thing to an anti-backlash gear is the Conical gear (a • misnomer).
> It can be used to load a gear train. I have used this in a design by Iain
> Hendry.
> http://bobfay.users5.50megs.com/newmill.htm
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Bob Fay wrote:
> The closest thing to an anti-backlash gear is the Conical gear (a misnomer).
> It can be used to load a gear train. I have used this in a design by Iain
> Hendry.
> http://bobfay.users5.50megs.com/newmill.htm
>
> I have tried using a second motor in the gear train with a slight reverse
> current. This pretty bulky.
>
> I think the gear you want is a sandwich of two gears that are spring loaded
> so the teeth oppose each other. This would work in a small gear train.
>
> There is another example of the conical gear at the end of this page.
> http://bobfay.users5.50megs.com/speedy.htm
> --
> Bob Fay
> rfay@we.mediaone.net
>
> http://bobfay.users5.50megs.com/index.html
> http://www.geocities.com/Heartland/Bluffs/7900/
> "Eric Sophie" <Legomaster@gobi.com> wrote in message
> news:GB7x2F.J0G@lugnet.com...
> > Tech question for us: Any body know what an Anti-Backlash gear is?
What set(s) include this "conical" gear?
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The CD-Rom does not explaiin how to use this piece, but in an earlier post I
wrote:
Ok, this is called a "Slip Gear" or "Torque Gear" It is used to prevent over
rotation by means of an internal clutch, the 2.5 - 5.0 NCM I belive means
the range of operable force applied before the clutch disengages. Nano
Centemeter of force. In short I used one in each hand of the Robot I am
building, after gearing the the motor 1 or two "steps" (8 to 24 tooth) I
then inserted the Torque gear, and ran the axle straight to a worm gear
assymbly, the hand closes with a good deal of force, then when the fingers
reach the thunb, the force is greater then the presecribed limits then the
gear starts to slip and thus preventing damage to the structure.
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=39790
They are really very handy if you can gear them for the proper application.
In lugnet.robotics, xenon@3dnature.com writes:
> Ram Meenakshisundaram wrote:
>
> > Isnt that the same as the white clutch gear. Here is a link to it:
> > http://w3.one.net/~hughesj/technica/registry/gear/gear_3.html
>
> Maybe I'm just clueless, but I've yet to figure out what
> one would do with this. The Lego Mindstorms booklet doesn't
> explain it at all. (My host laptop computer runs Linux, and
> so if it is explained in the nifty multimedia CD-ROM that
> came with Mindstorms, I've missed it.)
>
> It took me weeks to finally figure out what the differential
> gear really was, and I'm still trying to figure out the best
> way top operate the brick seperator. Didn't even know what it
> was until I saw it named in a catalog.
>
> > Ram
>
> Chris - Xenon
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In lugnet.robotics, Jonathan Wilson writes:
> What set(s) include this "conical" gear?
Far as I can tell, these are the gears used in the gearboxes in 8880, 8448,
8480, and prob'ly others.
ROSCO
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Eric Sophie wrote:
>
> The CD-Rom does not explaiin how to use this piece, but in an earlier post I
> wrote:
>
> Ok, this is called a "Slip Gear" or "Torque Gear" It is used to prevent over
> rotation by means of an internal clutch, the 2.5 - 5.0 NCM I belive means
> the range of operable force applied before the clutch disengages. Nano
> Centemeter of force.
(I think we established that this is Newton centimeters - a force of between
two and a half and five Newtons applied at a distance of one centimeter will
cause the gear to slip...or half that at 2cm, a third at 3cm and so on).
> They are really very handy if you can gear them for the proper application.
That's true - but I find they are almost always WAY too stiff for the
applications I have - by the time they've started to slip, the motor
has usually stalled - or ripped the robot to bits.
--
Steve Baker HomeEmail: <sjbaker1@airmail.net>
WorkEmail: <sjbaker@link.com>
HomePage : http://web2.airmail.net/sjbaker1
Projects : http://plib.sourceforge.net
http://tuxaqfh.sourceforge.net
http://tuxkart.sourceforge.net
http://prettypoly.sourceforge.net
http://freeglut.sourceforge.net
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Steve Baker wrote:
>
> I find they are almost always WAY too stiff for the
> applications I have - by the time they've started to slip, the motor
> has usually stalled - or ripped the robot to bits.
Hmm interesting. I only have one clutch gear (the one that came with RIS
1.5), and it is too *loose* to really be at all functional. I've also
read that the clutch force tends to drop in them the more they are used.
--
Regards
Micah J. Mabelitini - LUGNET #918
The University of Kentucky
SECC Middlesboro Academic Skills Resource Center
accutron@kih.net - http://www.users.kih.net/~micahx/
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Oh , right , Newtons , I was saying Nano centameters! thanks....I guess you
need a fair amount of gearing and distance to use these gears effectivly
along with opposing resistance, I love the way it works in the hand I
developed, infact in included a touch sensor in the thumb inorder to reverse
directions automatically, but the gear works so well, I often just rely on
timming, when using the Arm in an unofficial testing manner....Eric
In lugnet.robotics, sjbaker1@airmail.net writes:
> Eric Sophie wrote:
> >
> > The CD-Rom does not explaiin how to use this piece, but in an earlier post I
> > wrote:
> >
> > Ok, this is called a "Slip Gear" or "Torque Gear" It is used to prevent over
> > rotation by means of an internal clutch, the 2.5 - 5.0 NCM I belive means
> > the range of operable force applied before the clutch disengages. Nano
> > Centemeter of force.
>
> (I think we established that this is Newton centimeters - a force of between
> two and a half and five Newtons applied at a distance of one centimeter will
> cause the gear to slip...or half that at 2cm, a third at 3cm and so on).
>
> > They are really very handy if you can gear them for the proper application.
>
> That's true - but I find they are almost always WAY too stiff for the
> applications I have - by the time they've started to slip, the motor
> has usually stalled - or ripped the robot to bits.
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Yes they do lose a little, I guess we always knew that would be the case, I
hate to see you not use the gear if it's to loose, reurn it for a new one if
you decide somthing really needs it. Also I consider this gear a "back-up"
in preventing mechanical failure, System controll being the supervisor (RXC)
Eric
In lugnet.robotics, Micah J. Mabelitini writes:
> Steve Baker wrote:
> >
> > I find they are almost always WAY too stiff for the
> > applications I have - by the time they've started to slip, the motor
> > has usually stalled - or ripped the robot to bits.
>
>
> Hmm interesting. I only have one clutch gear (the one that came with RIS
> 1.5), and it is too *loose* to really be at all functional. I've also
> read that the clutch force tends to drop in them the more they are used.
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"Eric Sophie" <Legomaster@gobi.com> wrote in message
news:GB91vJ.21x@lugnet.com...
> Ok, this is called a "Slip Gear" or "Torque Gear" It is used to prevent • over
> rotation by means of an internal clutch, the 2.5 - 5.0 NCM I belive means
Ncm.
> the range of operable force applied before the clutch disengages. Nano
> Centemeter of force. In short I used one in each hand of the Robot I am
Newtons x cm. Not nano. :)
Iain (the metric pissant)
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