Gears, most wanted

[efferman]

I just wish for a 8 tooth gear that can run free, and likewise a 24 tooth. Would expand the possibilities to make compact gearboxes.

a 24 tooth clutch gear is allready made, and i think the walls would be on a freewheel 8 tooth to thin.

If you aim for participating in Lego World etc. then i prefer not to modify existing parts, not that i haven't done it, but still i rather not. I look with interest at the post with ideas here, and hope TLG sees them, allthough i know 3D printing is an opportunity you might want to take advantage of. Somehow i am just a bit concerned if 3D printing doesn't devaluates the LEGO Brand. Just a consideration.

Yes, Lego world and other fairs should be third party free. And yes i hope tlg thinks about some ideas in the inventor threads but some of them are to special and has to complex forms to produce it economiocal. my portal hub is like a portalhub on a unimog should be, but it can only used as portal hub and it is fixed on one gear reduction. i think it can be produced in a mold and so much cheaper than printed. but tlg will never do that. our custom parts are to special and wanted by to less people to make sense for lego. but lego, please think about a change in the large turntables and make it like the small one. every wobbly build on 8043 and 42009 would be history.

The turntable is design to be the base for rotating cranes. Sure the turntable has it potential use here. But the kinematic geometry of gear elements behind the stationary sun gear and the planet gear must be be precise on many factors

aah now i understand these gears are not only for this strange thing. it is simply like the parts which alasdair has make to get three functions through the turntable.

[Moz]

Yes, Lego world and other fairs should be third party free

Yes, but some Lego-and-stuff shows are open to anything that looks like Lego. Brickvention in Australia, for example, just requires that the visible parts of the model look like Lego - you can use non-Lego plastic parts on the outside, plus internal reinforcing and parts made of whatever you like. It makes the model building more impressive, but obviously pure-Lego models tend not to look as exciting. No-one's going to make Ryan McNaught's giant helicopter model using only Lego parts.

[Boxerlego]

I made a list of the current kinematic gear pairs. The only problem is that none of these gears have a proper stud length to be geometrically correct with Lego. At the bottom of the list you can see the Turntable has a kinematic pair with the differential gear but the stud distance still remains an issue. A 32 tooth gear with a 16 tooth gear is a kinematic pair that would fit precisely with Lego geometry.

Edited May 1, 2014 by Boxerlego

[DrJB]

Not sure what you mean exactly by 'kinematic pair' ... your lists is more about 'misfits'. Not every gear will mesh with any other, and yet have a spacing that is multiple of a stud length (M). Only some given combinations are allowed. If however, you still want some 'non-standard' gear ratios (such as those you're showing above), then you'd need more work, to come up with something a bit smarter than a full stud length. The gearboxes on the 8448 and 8466 have spacing of 2.5 stud length, and that is because they use technic 1x2 bricks that have 2 holes, not just one ...

I can't find it now, but I know of a graphical tool that shows you the spacing you need and few optional constructions if you pick any combination of the standard lego gears. Some of them require that you go diagonally with the construction, not just up-down or side-to-side ...

Edited May 1, 2014 by DrJB

[vmln8r]

^ http://gears.sariel.pl

&

[DrJB]

Thank you, that's exactly it.

[Boxerlego]

Not sure what you mean exactly by 'kinematic pair' ... your lists is more about 'misfits'. Not every gear will mesh with any other, and yet have a spacing that is multiple of a stud length (M). Only some given combinations are allowed. If however, you still want some 'non-standard' gear ratios (such as those you're showing above), then you'd need more work, to come up with something a bit smarter than a full stud length. The gearboxes on the 8448 and 8466 have spacing of 2.5 stud length, and that is because they use technic 1x2 bricks that have 2 holes, not just one ...

Kinematic pair is very simple to understand. I made the kinematic gear pair list showing all the current Gears pairs that have a 1:2 ratio but none of them is Geometrically correct with with Lego's Geometry.

I can't find it now, but I know of a graphical tool that shows you the spacing you need and few optional constructions if you pick any combination of the standard lego gears. Some of them require that you go diagonally with the construction, not just up-down or side-to-side ...

Connecting the gear diagonally will not work here because the gears will not function geometrically correct with Lego's paradigm and It will be off centered. In order for this kinematic machine to function perfectly you have to connect the gears on the vertical or horizontal plane.

I recommend to watch this

so you can see how precise this kinematic machine can travel in a straight line. To achieve this kind of perfection with lego gears everything should add up to a whole number so the line will be perfectly straight and pass over the exact center of the sun gear. Any imperfections with the gear distance will not make a straight line of travel because the geometry does not perfectly pass over the center of the sun gear.

[Hrafn]

I made a list of the current kinematic gear pairs. The only problem is that none of these gears have a proper stud length to be geometrically correct with Lego. At the bottom of the list you can see the Turntable has a kinematic pair with the differential gear but the stud distance still remains an issue. A 32 tooth gear with a 16 tooth gear is a kinematic pair that would fit precisely with Lego geometry.

Why won't a 1.5 stud offset work? One way to do it is these two next to each other: . Or you can use parts like these , suitably spaced on an axle and reinforced so that they don't slide on the axle due to meshing forces.

[Boxerlego]

Why won't a 1.5 stud offset work?

Everyone one of those gear pairs will work, the problem is that you have to compensate for the extra stud length at the end on the liftarm so it will be able to travel in a straight line and pass directly of the center of the sun gear. I've made the 1.5 stud offset work, here is a

of it, but the rotating link is 3 studs long and the total stud length from the center of the sun gear is 3.5 studs long so there is a 0.5 studs offset between the two. Sure you can use some of those elements to compensate for that 0.5 offset, but the 32t gear with the 16t gear does not need these compensations and is able to fit precisely with in Lego geometry.

[DrJB]

How was I (or anyone) supposed guess what you were after? Your original post was very vague at the very best, and when people (e.g. I) ask questions ... you start lecturing!

You should be VERY clear in your post, so you do not get equally non-sensical answers. I stand by my comments, as nowhere in your post you hinted that you were after replicating a 'certain' gear mechanism (the one in the video).

Lastly, you CAN reproduce a similar mechanism with diagonal bracing ... I have a 7-volume book-set (MIR Editions) on mechanisms, and the one in the video is one of the simplest.

Kinematic pair is very simple to understand. I made the kinematic gear pair list showing all the current Gears pairs that have a 1:2 ratio but none of them is Geometrically correct with with Lego's Geometry.

Connecting the gear diagonally will not work here because the gears will not function geometrically correct with Lego's paradigm and It will be off centered. In order for this kinematic machine to function perfectly you have to connect the gears on the vertical or horizontal plane.

I recommend to watch this

so you can see how precise this kinematic machine can travel in a straight line. To achieve this kind of perfection with lego gears everything should add up to a whole number so the line will be perfectly straight and pass over the exact center of the sun gear. Any imperfections with the gear distance will not make a straight line of travel because the geometry does not perfectly pass over the center of the sun gear.

Edited May 2, 2014 by DrJB

[allanp]

I've updated my diff design, now modelled in google sketchup. Problem is that program cannot handle sizes that are very small so these models are 1000 times too big (so instead of a gear being 12.7mm it's now 12.7 meters!). Anyone know of a good free program which I can use to down scale them? Would you like me to send you the files Efferman?

Edit: Oh, I also worked on a 56 tooth gear with the holes being in the same place as the one in the lego movie whilst still being only 56 tooth to make it fit with an 8 tooth gear easily on a beam. Unfortunately I think the outer holes may be too close to the edge to use a chain or tread links.

Edited May 2, 2014 by allanp

[efferman]

sure you can send me the files, but i dont know if my inventor can read it, and how to downsize it.... dont know.

by the way, looks great the diff and yes the outer holes are to close at the teeth

[allanp]

What file formats can you read?

[efferman]

roundabout 15 so which extension uses your software?

[notareal]

I've updated my diff design, now modelled in google sketchup. Problem is that program cannot handle sizes that are very small so these models are 1000 times too big (so instead of a gear being 12.7mm it's now 12.7 meters!).

You can still use sketchup, just need a bit different strategy. First, made a simple "base" model (cube, cylinder, ect) in a correct scale as a component (to make a component, select the model and use edit > make component). Then duplicate that component and scale it 100x (or 1000x if needed) and start editing the up-scaled component. When you ready, just remove the scaled up component and you have all details in the small component (that otherwise is impossible to edit).

Edited May 2, 2014 by notareal

[allanp]

I can export to .dae or .kmz but I'm sure there's a .stl converter somewhere.

@notareal thanks for the info I'll have to try that out. EDIT: Just tried rescaling my larger parts by 0.001 and they have come out perfect! I thought I already tried that, guess not . NOTHER EDIT: Ah, last time I tried it I didn't make it a component first, making it a component is what made it work this time. Thanks man

Edited May 2, 2014 by allanp

[efferman]

Dae or kmz are not in the list

[allanp]

OK, well I can rescale them now but if you still want the files I will get a .stl converter.

Edited May 2, 2014 by allanp

[efferman]

When you can rescale yourself there is no need for this. When you upload it to shapeways, you can get a 15 percent off on strong and flexible plastics when you order till may the 12th.

[allanp]

Kewl!

[Boxerlego]

How was I (or anyone) supposed guess what you were after? Your original post was very vague at the very best, and when people (e.g. I) ask questions ... you start lecturing!

You should be VERY clear in your post, so you do not get equally non-sensical answers. I stand by my comments, as nowhere in your post you hinted that you were after replicating a 'certain' gear mechanism (the one in the video).

Lastly, you CAN reproduce a similar mechanism with diagonal bracing ... I have a 7-volume book-set (MIR Editions) on mechanisms, and the one in the video is one of the simplest.

I want to point out that your VERY vague on you diagonal bracing, Show me the LEGO element that would support this and what is the precise angle that you think will work,

[DrJB]

I want to point out that your VERY vague on you diagonal bracing, Show me the LEGO element that would support this and what is the precise angle that you think will work,

Check Sariel's applet (above). I was merely you expand your horizons a bit and need to think BEYOND the horizontal/vertical spacing ... which can only be incremented by 0.5 stud (or module).

If you think of a matrix of pinholes (kinda like beams/liftarms stacked above each other) then you need not restrict yourself to X or Y motion only i.e., the gears need NOT be on the SAME row or column of the matrix I mentioned above. Makes sense?

[Hrafn]

Check Sariel's applet (above). I was merely you expand your horizons a bit and need to think BEYOND the horizontal/vertical spacing ... which can only be incremented by 0.5 stud (or module).

If you think of a matrix of pinholes (kinda like beams/liftarms stacked above each other) then you need not restrict yourself to X or Y motion only i.e., the gears need NOT be on the SAME row or column of the matrix I mentioned above. Makes sense?

Or the angled beams (which are at atan(3/5) or about 53.1 degrees) or the tri-liftarms (and wedge belt wheels) at 120 (and 60) degrees. 1/2 stud offsets aren't too hard either. Studs are 8mm, but bricks are 9.6mm tall and plates are 3.2mm. Between all of those tricks, I've found good meshing geometries for most gear pairings and have candidates to try out for some of the others. Whether these solutions are practical is another matter...

Edited May 3, 2014 by Hrafn

[Boxerlego]

Check Sariel's applet (above). I was merely you expand your horizons a bit and need to think BEYOND the horizontal/vertical spacing ... which can only be incremented by 0.5 stud (or module).

If you think of a matrix of pinholes (kinda like beams/liftarms stacked above each other) then you need not restrict yourself to X or Y motion only i.e., the gears need NOT be on the SAME row or column of the matrix I mentioned above. Makes sense?

Makes perfect sense. See the diagonal bracing and the non-horizontal/non-vertical gear alignment, everything is there just like you wanted. However, the 12 tooth gear is not big enough to mesh with another 12 tooth gear, so in-order to add the second gear on for the kinematic motion to happen I needed to use two 16 tooth gears in the end, which brings me back to the thought on using the 32 tooth gear along with the 16 tooth gears.

Edited May 3, 2014 by Boxerlego

[efferman]

a suggestion on the idea collectors thread let me make a inline differential for tatra axles