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Nate
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« Reply #15 on: September 20, 2015, 12:56:12 AM »

Well said. I agree. And in the case of the gears we're discussin g Im suspiciou s of the line of action, I dont believe there is one. More of a constant
rotation. But as I said, I'd like to hear of the experienc e in building a set..

I'd be curious to see how well it produces circular 'gears' too.
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ArtF
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« Reply #16 on: September 20, 2015, 06:09:45 AM »

Nate:

   You know, I like to sleep on it in things like this, because although things have a habit of looking simple,
Ive found underlyin g complexit ies in most algorithm s of this sort. Your math is much better than mine, I think its
obvious from your responses to questions such as this. I appreciat e that expertise being around. 

    Justin was right of course in his statement that they must slide, mine is a confusion with sliding that
causes a angular change and sliding that doesnt. I had discounte d sliding that doesnt.  As you pointed
out well, sliding in the tangental direction has no effect on the rotationa l velocity where sliding in other
vectors necessita tes it.
   Personall y, I have trouble thinking of it as sliding at that point as it implies more than than
its reality. Since the contact point is touched only instantan eously and the next contact point is moving
in its own rotation coordinat e system to meet the next contact point at its admittedl y different speed, the result
is a roll along an involuted trajector y curve where each point meets perfectly at its own relative speed with the next
contact being the proper distance and offset away. It isnt something I think of as a slide, but it IS sliding.

   I find when I start to compete multiple coordinat e frames of referance I get confused easily as to context
in those frames. Consider any single point and they meet perfectly in time and space throughou t the
curve, and for this I picture no sliding. A result of knowing that temporall y each point meets perfectly
with the next one in space when designing the contact curve. The curves are though, of different lengths.
 Enough to hurt my head. Smiley

   So I had to look into some other assumptio ns to ensure I have it right. The involute is the best shape to my
mind as it keeps the line of action as pure as possible, but what about circular teeth? From a freshen-up look
this morning at my reference s, it appears round teeth are fine, but with the proviso the contact point is kept to the
 pitch circle point or as close as possible, something which can be done by using the proper generatin g curve.
 
   In essense, the method gearify uses, is a valid one, since it is rolling a gear around another its doing a virtual hob,
Im unsure if the generatio n profile changes to match the contact point, but its a valid a way as any other in terms of
the generatio n, and if the contact point is relativel y stable, then Id say a load is fine. I do think though for a round
tooth gear to work, the generatin g profile would change from gear pair to pair in order to match that requireme nt.

  In any event, thx for the explanati on, I like to have my confusion s in math or terminolo gy fixed as I go. Smiley


Art


 



 Thx for the update of my internal model
on how that works.



     
 
 
   
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Nate
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« Reply #17 on: September 20, 2015, 12:45:07 PM »

If I understan d the videos correctly, then gearify may produce gears for transferr ing load, but it will do so by accident more than design.

A better example for non-involute gears is the imaginary gear feature in gearotic, or cycloidal gears tha were historica lly used in clocks.  The 'virtual hob' in gearify seems considera bly less sophistic ated than what would be necessary to produce one of those.
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ArtF
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« Reply #18 on: September 20, 2015, 01:44:05 PM »

Nate:

 Perhaps, I find noncirclu ars a bitch to subtract, but its possible it works as well as any other I suppose.
   I know when I began subtracti on as a build method it really had a habbit of showing flaws in my thinking,
but round teeth may be better at it. I have sent the author an invite to join us, I was pleased he contacted me,
he may be able to tell us more about the way it works. They look nice in any event. Smiley

>>A better example for non-involute gears is the imaginary gear feature in gearotic

  Actually, those were an attempt to produce a floating pressure angle involute. . Im amazed how popular they were,
I guess I may have to add them back in.. maybe Ill put them in the new wizards program.. let people script some
changes to them.

Art


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John T
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« Reply #19 on: September 21, 2015, 08:33:04 PM »

Hi Art
I am not qualified to weigh in mathemati cally,  all I know is that my involutes don't slide if I get the center distance right. This is based on observati ons of my clocks running for years, If the center distance is off all bets are off.

John
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ArtF
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« Reply #20 on: September 21, 2015, 09:01:17 PM »

Hi John:

  Its really a matter of definitio n and context .. normally, if a wheel rolling on another slips, the speed of the two wheels must differ
for a moment, but in the case of the teeth in a gear, they can slide and not affect rotation as its a slide thats in a direction al
vector that is the same as the motion..t he slide allows the rotation. That having been said, its not very observabl e. More math
than visable reality. This slip happens while two curves roll off each other in their own motion paths...

  Ive read more treatises on tooth profile than I care to admit, but in the end, though everyone has a wizbang new profile every couple
years, they always come back to the involute it seems. Its just the best compromis e you can  make for the job of gearing. I laughed the other
night in fact when I came on Gearotics Knuckle Gears. I thought I invented them, they were made years ago by someone, tested and found
to be wanting in strength. ( But their pretty.. )..

   I actually have gearify now, I've been in contact with Michael , its creator and we've swapped programs. (Developer s courtesy Smiley )
Its quite well written and for those inclined to that type of gear Id heartily recommend it. He's been very cleaver in how he lets you design
the two gears.

Art
 
 
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Nate
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« Reply #21 on: September 22, 2015, 03:20:47 PM »

I am not qualified to weigh in mathemati cally,  all I know is that my involutes don't slide if I get the center distance right. This is based on observati ons of my clocks running for years, If the center distance is off all bets are off.

Here's a really nice animation:

https://www.youtube.com/watch?v=14yMFdgWM-A

It's a rack and involute pinion, but we can think of the rack as being a really big gear - so big that we don't notice the curvature .

It should be obvious that the teeth on the rack don't move up and down at all, and that the teeth on the pinion move downward (and sideways), just to the side for a moment at the bottom, and then back up (and sideways).

That means that the contact point on the rack is never moving up and down, and the contact point on the pinion almost always is.   How can that happen if they aren't sliding against each other?

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ArtF
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« Reply #22 on: September 22, 2015, 08:00:47 PM »

Very valid point, can actually be seen easier in Gearotic if you slow down the rotation on the circ gear tab, ( better resolutio n that way..)

Art
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jmurphycnc
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« Reply #23 on: September 23, 2015, 09:56:04 AM »

I have purchased the "gearify" software, and it is certainly fun to "play" with. Since I was a metal machinist for many years, I didn't really think this was going to produce "Technical ly" accurate informati on for practical use, but it has provided some enjoyment (toys for the granddad and the grand-kids).

My only drawback is that the dxf output from Gearify is not compatibl e with my Aspire software, so I have to do the "save and convert" or "Save as" in another program before it becomes importabl e.

For the money, I'd say it fair value.

John
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ArtF
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« Reply #24 on: September 23, 2015, 11:03:17 AM »

John:

  Yes, DXF out put can be a bear to match up with everythin g else, its a very nonstanda rd standard. . Smiley . At Gearifies price
point I think its a bargain.

Art
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Mooselake
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« Reply #25 on: September 23, 2015, 01:08:36 PM »

Based on one attempt Gearify may not import DXFs from Gearotic.   I created a 4 sided gear in Gearotic, saved it as a DXF without toothing (which may be the problem.. .), then tried to import it into the Gearify demo.  No luck, while it didn't report an error nothing imported.

In the non-existent world of unlimited time, I was wondering if Gearotic could add a way to have optional plugins, and Mike could modify Gearify and offer it as a Gearotic plugin.  It'd probably take an Art clone or two before that'd happen, not to mention Mike deciding it'd help pay those school loans.

Nice to see that there's other interest in Gearify, and that Art and Mike are looking at each other's product.

I didn't see any equivalen t to plating/boxing in Gearify, and haven't gotten far enough in the tutorial (giant log pile in the yard...) to learn anything about gear carriers (or whatever the correct term is) to make working devices.  How did you handle it, John?

Kirk
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ArtF
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« Reply #26 on: September 23, 2015, 01:43:19 PM »

Kirk:

  The new scripting system  is coming along quite well, its starting to look impressiv e, and it will be my initial attempt to try to hook more things together.
Once its complete, Im hopeing it will offer a way to allow extra objects to be added to gearotics total, or to
massage various data that Gearotic or any other program puts out. As I've said before I hope to allow DXF imports ,but havent needed
them till now. ( Though spokes and indicator s and such are all just dxf's so Gearotic has been able to load DXF's for some time..
  While Auggie will not be the final way to do this, its scripter will be involved I suspect as well as the ability I need to come up
with to attach hardware. Im hopeing to have a Visual Studio project thats open source to hook to Auggie and another to add objects
to Gearotic. AllObject s in Gearotic are encapsula ted in a single class called a "3dObject Class", it hold all informati on needed to make
and simulate any object in Gearotic, so I really hope to get to the spot where I can allow others to define an object, so that it
imports to Gearotics database for machining , planning, or putting in a box.  We'll see how this year goes.. Smiley , I have several requests
and small bugs to get of the way from this past summer. Ill put more informati on on a post in the release topic , it time I posted a note to
new users as to what to expect this year.

Thx
Art


Art


 
Art

     
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Mooselake
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« Reply #27 on: September 23, 2015, 01:59:58 PM »

Ill put more informati on on a post in the release topic , it time I posted a note to
new users as to what to expect this year.
The unexpected things are always the best part of every Gearotic developme nt season Smiley

Kirk
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Gearify
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« Reply #28 on: September 23, 2015, 04:14:04 PM »

Hello All!

This is Michael Valle, and I am the creator of Gearify. I have been enjoying this discussio n and I wanted to add some comments.

I want to begin by saying that I appreciat e ArtF's perspecti ve of Gearify and Gearotic being complimen tary rather than rivals/competitors. I think his analysis of Gearify's current limitatio ns are accurate.


My initial objective when creating Gearify for my father's project, was to help him produce an internal eliptical gear mechanism with teeth that would neither slip, nor grind to  a halt. I had a strong math and programmi ng backgroun d, but at the time, no knowledge of the formal theory of gearing. I walked into a coffee shop with a pad of paper and played with a bunch of different ial equations . I walked out with a solution on paper, not only for elliptica l gears but for any reasonabl e shape. My solution, however, only described smooth, toothless gears. Producing the shape of the teeth puzzled me until I was on Winter break from college, and I devised the subtracti on method and produced the very first version of Gearify.

I didn't realize at the time but what I had essential ly done was created a piece software that:

1. Violates the fundament al law of gearing.
2. Gives you all the goodies you are entitled to if you are willing to violate that law.

Fewer constrain ts = More degrees of freedom. That's the philosoph y behind Gearify.

An excerpt from Gearify's user manual:

"The creation of gears for industria l applicati ons is
a highly developed engineeri ng science. Gearify is only partially based on this science, and
instead relies on an original approach using Different ial Equations, Numerical Methods, and
Computati onal Geometry in order to allow more freedom of design."


HOWEVER! It is my hope that I can eventuall y find or produce a suitable generaliz ation of the involute tooth concept for arbitrary non-circular gears. So far I have the following possible strategie s:


1. Find some credible literatur e with a clear and reasonabl e approach to generaliz e involute teeth to non-ciruclar gears (no luck so far)
2. Devise my own generaliz ation that at LEAST removes vibration (I have some ideas)
3. approxima te the non-circular shape as a series of circular segments and use appropria te involute teeth per segment (meh.. I don't even yet know if this makes sense)
4. Allow the user to upload a "virtual hob" (which Artf mentioned) so that the portion cut away from the subtracio n process can be larger than the tooth itself. This is a big feature on my TODO list. May not solve the issue but may get me closer.

So that's where I'm at with involute teeth. Its definitel y my most requested, and desired feature, but as ArtF mentioned, it is very very hard to involute tooth a non-circular gear.

Let me comment briefly on DXFs since this is a key issue for interoper ability of Gearify and Gearotic. Gearify makes use of the popular NetDXF project https://netdxf.codeplex.com/ for all of its DXF importing and exporting functions, which is still being developed and maintaine d. They recently included support for Binary DXFs, and are still weeding out bugs in general (I actually contribut ed to the project by writing the Spline elevator). I have yet to update Gearify's NetDXF reference s to the newest version, so when I get a chance to do so, that may fix the compatibi lity issues! Otherwise, be aware that Gearify currently only imports and exports ASCII DXF files. In any case, this will continue to improve as that project is developed . Smiley

As for future updates, I have an arbitrary non-circular rack and pinion gear interface in the works, as well as an extended "Astronome r" interface . Non-circular planetary gears are of great interest to me, and I have found a solution that allows for more symmetric al and less eccentric designs. the current interface produces a class of gears that are so eccentric they are difficult to build.


Feel free to ask me any questions or offer ideas for how you would like to see Gearify improved, or possible solutions for how to make the gears more suitable for applicati on. Smiley

Thank you all!

-Michael Valle
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Nate
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« Reply #29 on: September 23, 2015, 11:10:48 PM »

...
HOWEVER! It is my hope that I can eventuall y find or produce a suitable generaliz ation of the involute tooth concept for arbitrary non-circular gears. So far I have the following possible strategie s:


1. Find some credible literatur e with a clear and reasonabl e approach to generaliz e involute teeth to non-ciruclar gears (no luck so far)
2. Devise my own generaliz ation that at LEAST removes vibration (I have some ideas)
3. approxima te the non-circular shape as a series of circular segments and use appropria te involute teeth per segment (meh.. I don't even yet know if this makes sense)
4. Allow the user to upload a "virtual hob" (which Artf mentioned) so that the portion cut away from the subtracio n process can be larger than the tooth itself. This is a big feature on my TODO list. May not solve the issue but may get me closer.

So that's where I'm at with involute teeth. Its definitel y my most requested, and desired feature, but as ArtF mentioned, it is very very hard to involute tooth a non-circular gear.

....

Feel free to ask me any questions or offer ideas for how you would like to see Gearify improved, or possible solutions for how to make the gears more suitable for applicati on.

My impressio n is that gearify produces 'roller' profiles which (in the idealized case) have a continuou s point of contact between the two rollers, rather than one that "jumps around" like the red dots in this youtube video:

https://www.youtube.com/watch?v=14yMFdgWM-A

Is that impressio n correct?

IMO Generaliz ing involutes to no non-circular profiles really isn't that hard. It's basically just like generatin g involute tooth flanks point-by-point.

I worked through the basics earlier this year: http://gearotic.com/ESW/FavIcons/index.php?topic=1313.0

For more advanced topics like how to use profile shifting I can't help you much.

I played with interpola ting the roll line as a series of circular arcs and putting involute teeth on those, but that can have mechanica lly undesirab le propertie s. For example, it won't work properly for non-circular gears with a fixed pivot.
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