Osmirik's Gearbox Finder

This script helps gearbox design by finding the optimal gears for a gearbox that fits inside a particular range of ratios. In other words: If you need a D220-D231 gearbox, enter 220 an 231 as the range below, and it will tell you what gears you need to get a final ratio of 220% to 231%.
The output format is specified as an equation: Each division indicates gears with that many teeth 'meshed', and each multiplication indicates a gear on top of another. It's simpler than it sounds, here's an example for a gearbox that has a ratio of 42%:

Formula	Cost
(3/6) * (5/6) = 42%	4 medium gears

This indicates that you should have a 3 tooth gear driving a 6 tooth gear, which is stacked with a 5 tooth gear driving a 6 tooth gear. Invisible in here, due to the shorthand is another 5 tooth gear, as a 3 and a 6 cannot be directly connected. Here's the shorthand ratios used:

Shorthand	Expansion
(3/6)	(3/5) * (5/6)
(6/3)	(6/5) * (5/3)
(4/5)	(4/7) * (7/5)
(5/4)	(5/7) * (7/4)

The cost column gives the cost in medium gears. Small gears are costed at nothing, and large gears are equivalent to 6 medium gears.

A few points:

The first result will always be the absolute cheapest way to create that ratio, assuming iron is your primary cost. Other results are listed in case the optimum result has a set of gears you do not have, or you are building a multiple-output gearbox and need several results to work with.
This tool does not design the gearbox for you. You still have to take the proposed gears and arrange them on the design board, and you still have to make it reach the output peg (adding gears as needed)
The cost value includes only iron for medium and large gears.
This tool does not handle multiple output gearboxes. If you're designing one, the tool can be useful in determining the best set for any one output and for determining the best set to get from one ratio to another, but you still have to do the work of trying to combine these for the best multiple-output box.
This tool does take into account what gears can be positioned by what other gears. It should never generate a pair of gears that are not possible to mesh.

For the existence of this tool, I owe my everlasting gratitude to Isomer, for hacking up in python the tool I originally used to search for the best gearboxes, Tamutnefret for upstaging me by having already created a list (that list now drives this script), Zubon, for his post containing price estimates for the gears, possible gear arrangements, and other information, to FaceAnkh, for making the sed one-liner to convert the original data into a format more usable for the database, Brant|SN and TheDude[OWRH] for their brief participation in the Distributed Optimal Gearbox Effort, and to Garan for his assorted contributions in IRC.

= ".intval($_GET['rmin'])." AND Speed <= ".intval($_GET['rmax'])." ORDER BY Cost"); if(isset($_GET['slashnotation'])) { while($line = pg_fetch_array($result)) { $newline = str_replace("(6/3)", "(6/5/3)", $line['description']); $newline = str_replace("(3/6)", "(3/5/6)", $newline); $newline = str_replace("(4/5)", "(4/7/5)", $newline); $newline = str_replace("(5/4)", "(5/7/4)", $newline); print("\n"); } } else if(isset($_GET['expand'])) { while($line = pg_fetch_array($result)) { $newline = str_replace("(6/3)", "(6/5) * (5/3)", $line['description']); $newline = str_replace("(3/6)", "(3/5) * (5/6)", $newline); $newline = str_replace("(4/5)", "(4/7) * (7/5)", $newline); $newline = str_replace("(5/4)", "(5/7) * (7/4)", $newline); print("\n"); } } else { while($line = pg_fetch_array($result)) { print("\n"); } } print("

Formula	Cost
".$newline." = {$line['speed']}	{$line['cost']} medium gears
".$newline." = {$line['speed']}	{$line['cost']} medium gears
{$line['description']} = {$line['speed']}	{$line['cost']} medium gears

\n"); } ?>