Gear sizing question

[msimpson]

OK I have a clock shown here
http://youtu.be/Ys4LtRwOrjk

Works very well.

However to get the hour and minute stacked gears to work i had to increase the size of a gear to get it to properly mesh.  I used the shift option when I created the pinion gear. I added .3 and that the gear diameter up to size so the teeth would fall where I needed them to.

Is this ok to do.  I have a clock where I have some fairly complicat ed stacked gears and on a couple of the gears I need them to mate.  I cant mess with the positioni ng, Pitch, or number of teeth so I need to lengthen or shorten the teeth so they have a better mesh.

Note that when I say stacked I am refering to one shaft inside another. IE Seconds shaft inside minutes shaft, inside hours shaft.

[John S]

Yes that's fine, industry does this all the while.
Strip any car transmiss ion and odds are there will not be a standard gear in the whole box.

All altered for strength, quiet running etc.

John S.

[ArtF]

m:

  One thing you can do, is when creating gears for such mechanism s, add a small amount of standard backlash to the first gear off a mesh.. That makes the shaft that small amount shifted. The backlash setting is there for just such a problem. GM makes the math
as close to perfectio n as it can, tolerance s mean that almost any gear will be ever so slightly tight if you use the "perfect" numbers. Backlash allows you to loosen thiings ever so slightly to take tolerance s into account..

  Gears then placed between those two shafts will mesh a bit looser.. I wont say better because that depends on the situation ..

Art

[ArtF]

m:

 By the way... VERY nice clock, I like it a lot..

Art

[msimpson]

I just finished a book. Its and illistrat ed guide to building the CNC I am now using for my gears.  I modeled the CNC down to every single nut and bolt so I could do exploded illistrat ions. When the web site goes public. I plan on a illistrat ed guide of that clock as well.  It will included step by step instructi ons as well as Gcode for all the parts in the clock.

I am also modeling the clock (hence the autocad questions).  It will be modeled in both Autocad and 3Ds Max.  3D modeling is easyer to do in 3ds and I can do animation s of assembly.  Autocad is better at outputtin g exploded drawings.  Autocade works better with solids and 3Ds is pretty much all Mesh.  Autocad will handle mesh as long as you arnt doing much with them.