GearHeads Corner

I have my spur gears cut with EDM wire machining.  The machine follows the dxf profile.  The gears are used for power transmission, so I need a fillet radius at the base of the tooth.  I don't see a way of adding it and manually editing the dxf file is tedius. 

It would be very nice is there was a parameter where I could enter the desired fillet radius.

Thanks,

John

John:

  Ive added this to my list and will look into allowing it as an option.

Thx
Art

While you're at it...

The gears of old "Geometric Chucks" from 200 years ago have semicircular tooth bottoms. It gives them a unique and characteristic look. Maybe you could add a toggle for that....

ahh, like the racks on the gta page. Ill add that to the list of
possible refinements as well.

Art

I give up. GTA page? I found this page which happens to have round bottom gear teeth...
http://www.gtapartners.net/?page_id=14

But no sign of a rack.....

They  cropped the image, but it looks like these three gears on in mesh....oops.

Another amusing image is on the wikipedia "gear" page. The helical gears, show in parallel and crossed configuration....oops.


Thanks Art!

Geometric chucks, which I'd never heard of before, are really cool.  Thanks, Justin.

I found a simulator here but it's too late to download and try it.

Kirk

Mooselake, put this word into the Google image search: guilloche

Justin;

I've been asked this question often offline, so to clairify, GTA (generalized toothing algorithm) tab in GM can only be found in developer version 4.80, lockdown version 4.67 does not.


Cheers
Bob  8)

While a semicircular root can be put on gears above a certain tooth count, I dont think they'd work on a gear that requires
a trochoidal curve at root. Id suspect meshing problems. Ill look into whats possible though in the code I use to generate the curves.

Art

JustinO wrote:Mooselake, put this word into the Google image search: guilloche

Thanks, Justin.  I've only heard of Rose Engines, never a lathe add-on, and been unable to find a software rose engine simulator since the real thing is way beyond my hobby budget.  Hope to try the Geometric Engine simulator tonight.

Kirk

Back to the original hijacking of this thread...
      Art, does GM only use hypo/epi cycloid generating circles equal to half the gear diameter?
      The gears with semicircle looking roots may be hypocycloidal as I think you've hinted. In order to be interchangeable, cycloid gears and racks have to be generated by the same diameter circle. That would mean no easy radial roots. The geometric chuck depends on interchangeability.
      If it is not a feature hiding unbeknownst to me, can you add specified root generating circle diameters for cycloidal gears, after you have finished everything else on the wish list, but before you take a break?

      Are you guys dropping by the Cabin Fever Expo this April? I'll buy you some fair food if you come.

Hi Jason:

>> Art, does GM only use hypo/epi cycloid generatin g circles equal to half the gear diameter?

  Yes, its one of my attempts to keep it easy on users heads. I looked at just about every gear generator program known to man,
from the very expensive to the modestly expensive, and came early to the conclusion that art of what GM "had" to do was keep things
easy on the head. Most programs have dozens of items to decide upon when generating a gear, and most of them had very little
impact on the actual gear, perhpas as little as a few % points in performance. So I made the epi's use only a half-diameter generator
so radial roots woudl be the norm. (Most clock makers of those that use epi's want the old time radial roots for the look).
  Now that we're two years after that decision, I sometimes see things that may indeed  be added without mucking things up too much.
Ill add to my list to see if this can be added, perhaps a % dropdown rather then implicitly specifying the diameter.
  If the generator can handle it without too great a recode time, Ill see if I can add it.

I "may" be at Cabin Fever, I havent as yet set any plans in stone. IF so, Ill buy. :)

Art