FILENAMES:

sm10utilathe_metric_gears.jpg
sm10utilathe_standard_gears.jpg

DESCRIPTION:

These are pictures of Southbend lathe change gear setups.
 
Posted by Mike Graham <mike@metalmangler.com>. 

The following description was provided:

=================================================================
<webmaster note - culled from RCM newsgroup>


On Mon, 01 Jul 2002 16:58:23 -0400, Mike Graham <mike@metalmangler.com>
wrote:

>  I'm going to have to go out there and take a good look at just what
>changes when I put the metric gears on there, then think about this for
>a while longer.  I figured it was something like that, but I was hoping
>there was some easy, standard solution. Thanks for the detailed message,
>eh?  I'll do a proper reply when I have proper info. 

  Okay, Dave, here we go.  I put on the change gears for the first time
and gave a good look at what is going on.
  I was going to try to do some ascii graphics, and then decided to take
some digital snaps instead.  See:
<http://www.metalworking.com/dropbox/sm10utilathe_standard_gears.jpg>
<http://www.metalworking.com/dropbox/sm10utilathe_metric_gears.jpg>

  Obviously the drive gear and relay gear are always in the equation,
and therefore can be ignored.  The banjo gear is also always in the
equation, so I think the bottom line is that if the standard gear train
was 1:1 then the metric gear train would be 2.54:1, so I need to find a
thread count 2.54 times the number of threads that I actually want to
cut.  So, if I was cutting 1.5mm pitch, then I'd need:
   25.4 / 1.5 * 2.54 = ~43tpi.  I'm not sure if I can cut 43tpi... I
might.  If so, it would only be off by about a thou per inch of thread,
no biggie.
   Does this sound right to you?