On 2009-06-30, F George McDuffee wrote:
On Mon, 29 Jun 2009 07:34:43 -0500, Ignoramus24381
wrote:
snip
This, from my point of view, can be addressed with a perl script
running on a laptop. It could tell me how many turns to make, etc.
Something along the lines of what I did with "Egyptian CNC". Ergo, the
laptop could say "turn the handle 3 times and stop at XX.XXX".
snip
One of the major problems is that the rotary tables tend to be
calibrated in degrees-minutes-seconds while the spreadsheet will
calculate in decimal degrees.

Well, if I write a script, I can convert decimal degrees into minutes
and seconds, no problem.

# Untested

my $angle = calculateAngleInDegrees( ... ... ... );
my $degrees = int( angle );
my $minutes = int( ($angle - $degrees) * 60);
my $seconds = int( ($angle - $degrees - $minutes*60)*60 );

print "Turn handle to $degrees degrees, $minutes minutes, $seconds seconds.\n";

If you will send me a good email address i will send a excel
program that calculates the decimal degrees for a given number of
teeth and then translates those decimal degrees into
degrees-minutes-and seconds [rounded to my rotary tables seconds
resolution]. If anyone else wants a copy of the spreadsheet send
me a good email address.

I went ahead and bought the index plate set w/ arms, after I got
the rotary table and now have a dividing head.

The spreadsheet is currently set-up for a 127 tooth gear [exact
metric change gear] but can be adapted to any number of teeth.
Note that even the dividing heads with the index plates have
problems cutting the larger prime number[100] gears such as 127.
Some of the very expensive dividing heads allow split or divided
indexing using 2 index plates, but this appears to be a royal
pain.

George, I like messing with scripts, so while I greatly appreciate the
spreadsheet offer, I would like to try to use my own scripts.

For our readers on a tight budget, you can download an excel
compatable spreadsheet from openoffice for free.
http://www.openoffice.org/product/calc.html
I just checked using my copy of openoffice 2.0 and calc opens the
spreadsheet but you may need to reset column width.

OpenOffice is awesome, I use it all the time, though less now with
Google Docs. I have a spreadsheet in google docs that calculates my
exact net worth based on prices of stocks and mutual funds that I own
etc. The function that they provide for it is called GoogleFinance.

One trick is to use a slitting or slitting saw to remove most of
the material before you switch to the gear cutter.

Good luck with your gear cutting and let the group know what you
learn.

I will definitely try. Thanks for the encouragement.

i