I’m not sure why, but we’re getting a clicking in the 775pro when attached to our custom turret gearbox. When the motor is taken off, neither the gearbox nor the motor bind up and all runs smoothly. Only when the motor is attached does a clicking and sticking happen. Any thoughts? When the motor isn’t attached, I’ve tried putting a small amount of side load on the motor to see if it starts to click (it doesn’t). I tried putting the screws in to see if they were too long and were hitting something, but I can bottom them out against the motor casing and it doesn’t seem to affect it. For what it’s worth, we’re using the press-on 12T 32DP gear from West Coast Products to a WCP 100T 32DP gear. I believe the designed separation distance was 1.752" (I don’t have the CAD in front of me, but I’ll check when I get home.) the plates were waterjet, so I’m wondering if there was some tolerance issue, but we’ve never had an issue in the past with gears meshing in a waterjet plate. Any thoughts on what would cause the motor to click?
Check to make sure all the little plastic fan blades inside the motor are in good shape. I’ve had a number of these break and get lodged in the motor assembly (a few of them have even shipped already broken) and it’s not immediately obvious unless you’re really looking.
Also be aware that these pieces tend to become projectiles if they decide to leave the motor housing while the motor is running.
We had multiple plastic fan parts come flying off of the practice robot 775PRO last night for no apparent reason. The 775Pro is used on our lift mechanism. It still seems to be operational. With a 4 second climb it hopefully will not require the cooling from the fans…
Just keep in mind that if the parts are coming off asymmetrically it might induce oscillation into the motor shaft that will likely reduce the performance and lifespan of your motor.
You said its a custom gear box we had a similar problem on our DT just file out around where the boss fits its probably a little too tight
I noticed the same thing on two of our 775 motors used for our shooters. We are using the GT2 timing belts and pulleys from West Coast Products. The belt is not over tightened, and the clicking happens when the motor is mounted to an aluminum mounting plate or a plywood mounting plate. Seems like something inside the motor rather than how we’re using the motor.
The motor still works fine and we’ve shot hundreds of balls through the shooter without issue, but it would be nice to know if the clicking is actually a problem waiting to get us or not.
*You guys should send a note to Vex and ask them.
We’re usually too busy building a robot to document and report issues! Now that I know someone else has seen this, I’ll try and get a video showing the clicking to send to Vexpro.
I’m fairly concerned because it feels like something is binding up on a 1 per rev of the motor output shaft. It’s actually fairly difficult to rotate the gears by hand when the motor is attached (but it can be done). I’m fairly certain the motor is powerful enough to power through it, but it can’t be good for motor life even if it can.
I’ll try opening up the boss a little bit and check the fan as mentioned above. This happens on both (as identical as possible) turrets with 3 different motors. I got worried when it happened on the first one, so I swapped out the motor only to find same the issue on other motors.
I had just figured I was doing something wrong. Since it’s a custom gearbox, there is always the possibility it’s an application error.
You might try powering the motors while disconnected from the gearbox and see if it still binds.
We had a similar situation with a 775 we had mounted to a 3:1 versaplanetary that was binding up for seemingly no reason. After taking the motor off and powering it without load it started ejecting bits of plastic (the fan blades). Needless to say we didn’t end up using that motor.
If the motors don’t present any issues when not attached to anything, you might want to look at the way you’re mounting them or how you’re attaching to the shaft.
It never hurts to contact Vex with these kinds of issues, even if it’s with a custom gearbox, they are generally quite helpful.
I don’t know if I would call it clicking, but we did notice one of our 775Pros on our competition shooter sounded different and seemed to run slower under load when individually powered versus the other two shooter motors. Wasn’t sure what to make of it.
How much clearance did you put for the motor boss on your gearbox? From the sounds of it you could be putting too much pressure on the bearing in the front boss.
Check to make sure the brushes are still attached, we have had a slew of motors where the brushes have broken off. 
The DXF I sent to our waterjet manufacturer had (I believe) a .005" bigger diameter, but being we had a rather large waterjet order caused them to run it on the “fast” mode, which can cause holes to be effectively smaller than I make them because there’s the waterjet roughness that happens. In fact, bearing holes normally need to be opened up slightly, but I’d rather them be on the small side than too large. In retrospect, I probably should have given it a bit more clearance, but .005" normally works fine for other motor mount bosses (i.e., CIM motors). Again, I’ll check when I get home. What would be the failure mode if that hole is too small? Crushing the bearing?
Before you modify the gearbox you could try it with the motor installed but without the 100T gear as you say both work independently.
Definitely try running the motor with no load, but if this happened to 3 different motors, all of them being defective seems unlikely(but not impossible). Just in case the fan blades or pieces of brushes decide to fly out, ensure that the vents are pointed away from people before starting the motor.
This too.
Just got home to check my CAD. The Center-Center distance was 1.752 (which, in retrospect is what it should be. [100+12]/64+.002 = 1.752). The hole diameter, however, was set to 17.8mm, which is the same as the motor boss (which means I didn’t give any allowance. Bad on me). It sounds like I’ll need to open that up just a bit.
For what it’s worth, here is an image of the turret gearbox: http://imgur.com/2TUTcVZ (You may have to click on enlarge to get the image to show up for some reason).