Gearotic Default Settings

[marklazarz]

One of the instructional videos suggested using a value of 0.48 for the "width" of involute wheels and pinions in order to induce a little backlash between mating gears.  Each time I start the circular gear module, this value defaults to 0.5.  Is there any way to make the 0.48 value stay put as a default value?  I put the word "width" in quotes because I would like to see a different term for this parameter, something more related to backlash because there are two "width" parameters, one being the face width of the gear and the other being just plain "width".

Another backlash question - is it best to set 0.48 "width" to both the wheel and the pinion or would setting it to either one suffice, leaving the other to the default 0.5?

Thanks,

Mark

[ArtF]

Hi Mark:

  I designed it to default to .5 because technically when you design a gear industrially you'd
want .5 as thats spec, and I feared Id forget that I used something different last time
and get an  unexpented gear next time. I'm not stuck on that position though, it was just a design
consideration as I developed. Ill consider allowing that to stick..

  I suggest .48 only because its what I use on wood, but really it can vary with material
and just whats being made. I would normally use the reduced "width" on the one gear
myself, but it can make sense to split the difference. Perhaps .49 on each makes more sense..
or closer to spec anyway..

  I agree the name is bad, too easy to get it mixed with face width.. I will rename it to make it
clearer..

Thx
Art
   

[marklazarz]

Art:

I think a different name would help.  In retrospect, if  parameters stuck as the new default, it might be problematic if they got too far out of whack, so a "reset" button would be necessary as well.

I've been using 0.48 for both wheels and pinions for wooden gears and it works fine for me.  Humidity in the summer plays havoc with moving wooden contraptions so more backlash is better around here.

Mark

[Dan Mauch]

I tried to find the video that mentions the width. So .48 provides backlash  for wooden gears when cut by a router. I cut most of my wooden gears with my laser. The laser cuts with about a .006 beam width on thin material. So I have been taking the gears in my cad program and adding an offset to compensate for the width of the cut. Does .5 mean that there should be zero backlash? How much backlash does .48 represent from .5? For lasers should the width be set at say .52 to compensate for the width of the beam cut?
Dan Mauch

Hi Mark:

  I designed it to default to .5 because technically when you design a gear industrially you'd
want .5 as thats spec, and I feared Id forget that I used something different last time
and get an  unexpented gear next time. I'm not stuck on that position though, it was just a design
consideration as I developed. Ill consider allowing that to stick..

  I suggest .48 only because its what I use on wood, but really it can vary with material
and just whats being made. I would normally use the reduced "width" on the one gear
myself, but it can make sense to split the difference. Perhaps .49 on each makes more sense..
or closer to spec anyway..

  I agree the name is bad, too easy to get it mixed with face width.. I will rename it to make it
clearer..

Thx
Art
     

[ArtF]

Hi Dan:

  The width number is a percentage, its the amount of space vs tooth, so using .48 means to make the tooth 2%
smaller than the hole. A setting of .5 is the theoretical "perfect" gear description as to the MOD/DP and involution
of that number of teeth. So yes, no backlash. While in the old gearotic we moved the shaft a bit, it makes much
better sense to use the tooth width to compensate for such things.

  For laser, I use .48 anyway , as I always find 2% is a good spot for me and the materials I use, though with
lasered acrylic I sometimes use .49. I rarely run into gears that are too tight in what I do, so its not a huge issue
around here. I suspect everyone will find their sweet spot, but having it as a percentage typically means once found
and your comfortable with it, you dont need to vary it when using various sizes of gear, it stays the same percentage.

Art