Based on parametric_involute_gear_v5.0 by GregFrost
It is licensed under the Creative Commons - GNU GPL license.
© 2010 by GregFrost
http://www.thingiverse.com/thing:3575

A theoretically simple tool set for creating finished gear models for 
use coming off a 3d printer.  Hard work done by Greg Frost, I am
adding features as I need them with an attempt to retain backwards compatibility
and ease of use.  Be warned original units were weird, it is suggested you use 
module to specifiy your gear, not circular_pitch.  

To create a gear compatible with V5.0, the conversion is:
 ||	module = circular_pitch/180
 ||	or 
 ||	circular_pitch = 180* module

**note circular_pitch does not correspond to the techincal deffinition which is
** measured in mm, however you may wish to use it if you have used gregFrosts
** original tool to create gears you wish to mesh with as the old definition 
** has been retained.

Modified several default values, and may modify units to match reality
Pressure angle changed from 28 to 20
found conversion factor to get "real" gears to come out of the tool


			==================================
			||		 To Do & Issues			||
			==================================
*replace values for set screw with table of good values
*clean up this read-me
*add simple useage template to main file
*change so that bore_diameter and shaft_diameter have sensible
precedence over eachother
*consolidate module into gear() w/ flags????
*add support for D and DD shafts
*large bores with thin walls will result in silly bosses

			==================================
			||		Usage					||
			==================================

*****************************  Gear arguments ********************************
**		arguments that share a line are alterantive, only one 				**
**		should be used all units are mm unless otherwise noted				**
******************************************************************************

These units make gears that can mate
	module_gear, circular_pitch, diametral_pitch	//circular pitch in wierd units
	pressure_angle=28,								//tooth pressure angle
	twist=0,


these units can vary between gears in the same train	
	gear_thickness			//thickness of thin web?
	rim_thickness			//tooth width
	circles	= 0				//qty of circular cutouts in gear face
	number_of_teeth=15		//number of teeth on gear
	clearance = 0.2			//
	rim_width=5				//
	hub_thickness=10		//Thickness of the center hub
	hub_diameter=15			//Diameter of the center hub
	bore_diameter=5			//center hole diam

Advanced Settings
	backlash=0,
	involute_facets=0
	no_bore					//will not insert a centeral shaft hole

*******************************  Fancy Gears *********************************
**	There are currently 3 fancy gears in the works:							**
**																			**
**		* gear_with_setscrew: a gear with a axial hole for a set screw to 	**
**		pin it to the gear 													**
**																			**
**		* gear_with_flange:	a gear with multiple holes in the center 		**
**		boss to bolt it to a flange or hub 									**
**																			**
**		* gear_with_D:	a gear with a D shaped center bore to mate to 		**
**		a shaft with a flat ground onto it									**
**																			**
**		* gear_with_DD:	a gear with a center hole intended to mate to  		**
**		a shaft with two flats on it	 									**
**																			**
**																			**
**	These all take the same arguments as listed above, in addition to 		**
**	any more that are listed in their writeup as shown below				**
******************************************************************************


******************************  Hub arguments ********************************
**	these make the sexy nub to let you bolt directly to a motor shaft		**
******************************************************************************

motor_shaft_diameter = 5;		//nominal OD of motor shaft gear will mount on
								//can be used instead of bore_diameter
motor_shaft_clearance = .6;		//clearance so your print will actually fit
trap_width = 6;					//across the flats for set screw nut
hardware_bore = 3.4;			//size of hole for set screw to fit through
center_height = 13.5;			//easily passed variable for gear center boss height


****************************** Typical Gears **********************************
**	some notes on creating gears 											 **
*******************************************************************************
In my personal expereince, a mod 2 gear is a happy gear, as it prints nicely
even on a very coarse .5mm nozzle, but still allows pretty small gears

Minimum number of teeth:
avoids intereference between a full depth pinion and a full depth rack
pressure angle 		Min N
	14.5			32
	20 				18
	25 				12


Standard Module Values (metric gears)
.3 		4
.4 		5
.5		6
.8 		8
1.0		10
1.25	12	
1.5 	16	
2 		20
3 		25


Standard diametrial pitches (US style gears)
Coarse		Fine
1 			20
1.25		24
1.5			32
1.75		48
2 			64
2.5 		72
3 			80
4			96
5		
6		
8		
10 		
12		
14		
16		
18