I’m wondering what the cheapest shifting gearbox is?
findrobotparts.com is a great resource for this. They have FRC parts from most of the major vendors. You can also sort through parts with filters (like only seeing 2-speed gearboxes). They then link to the product pages from all of the vendors that sell that product.
Here is the page listing all of the 2-speed gearboxes: http://findrobotparts.com/gearboxes/categories/5/tags/17. You can click on all the links in the list and find the cheapest one, or use the filters on the left to refine the search to make your life easier.
Is that really the right question? If money is your top consideration, you should focus on getting the best performance you can out of single speed gearboxes. Once you decide that a single speed is not good enough, get the best value for your requirements! A well selected, robust, suitably powered single speed gearbox is likely better than a cheap, poorly selected shifting gearbox.
As you price shifters, also consider the fact that unless you’re going to shift with a servo, you will need to add a pneumatic cylinder and solenoid valve for each gearbox if it isn’t included in the sale price, and if you don’t have it already, a compressor, regulator, gauges, pressure switch, PCM, tank, gauges, tubing, etc.
While I entirely agree that shifting gearboxes are generally quite expensive for their added value, I don’t think being budget-constrained, even tightly, should automatically mean not to go two-speed.
I believe that in the case that a team has built an effective, simple robot, the value of a COTS shifting gearbox, over a single-speed, may well be greater than spending the same amount of money on a new subsystem.
This will always depends on the strategy and actual budget. But for example, if adding shifting-gearboxes and improving mobility improves functions of higher strategic priority more than other improvements per amount of money spent, then buying shifting-gearboxes is honoring the priority list and keeping the robot a simpler specialist.
In any case, you must determine the value of shifting vs other functions per cost for your own team. My final note is that while a custom shifting gearbox can be cheaper and potentially add the same value as a COTS option, you must be very confident in your manufacturing to justify this. A poorly made custom shifting gearbox can easily be less value per cost even than a single speed gearbox.
Here a few of the main lower cost options:
2 CIM Ball Shifter
WCP Dual Speed
AndyMark RocketBox
AndyMark Super Shifter
All of these are pretty similar in price, and the best option depends on the type of drivetrain you are running. WCP Dual speed has an optional WCD configuration that makes it very easy to do a WCD, and I really like the gearbox overall. 3CIM and flipped CIM add extra cost.
Good luck!
Remember the saying, cheap is expensive. Sometime what looks cheap turns out to be expensive in the long run, just keep it in mind.