GearHeads Forum

Robert:

  Yeah, not very intutive, but when you think of it, that area under the rack is really
the rim of the gear.. were it round..

Art

Perfect, works great.  I would have never figured that out for a rack.  Thanks.

Robert

Hi Robert:

 The thickness is controlled by the Rim Ratio on the spoke tab up top. You can make it thicker or thinner as you go up or down in modules. It generally a % of the tooth height to keep
is regular, but the rim ratio allows that to be overridden.

Thx
Art

When making non circular gears and choosing racks, i can set the length of the rack (through number of teeth), the thickness of the rack, through the thickness tab  but I can set the width of the rack.

I am using .25 thick acrylic sheets and laser cutting.  Therefore my thickness will always be .25.  My length is controlled by the number of teeth but I can only change the height of the rack by changing the module.  I am using a module of 1, pressure angle of 20.  This gives me a rack with a width of .22 inches or so.  If I go to a modules of .5, pressure angle of 20 my width is .1 inch or so. 

I need more meat under my rack so it is less fragile.  I would like to be able to change it just like I can the diameter of the spur gear which I use as the pinion.  Is this possible, am I missing something, or is it a bug.  My uneducated guess is that you would change the width. 

This is not a show stopper for me as I can modify the dxf in my cutting software to add some width.  It is somewhat of an inconvenience however.

Thanks

Robert