How do these gearboxes compare?
How do these gearboxes compare?
One is a shifting gearbox. The WCP one has “snowman holes” to mount the CIMs with which can cause gear grinding unless you print something to fill the other side of the “snowman”. Check the CAD for more info.
The 3-CIM ballshifter will mount to a 1.875" versakey pattern (or a versablock) if you’re using the 3rd stage (which most of the time you will be). The WCP SS will mount to the holes in a WCP gearbox bearing block, which requires a precision 1.500" hole to be milled into the driverail. Alternatively, it can be mounted with an odd hole pattern and the bottom corner screws.
Why would they make a gearbox that is likely to experience gear grinding?
The “snowman holes” allow you to attach different sized pinion gears to a CIM/NEO. You have the option of 11, 12, 13, or 14 teeth, using one side or the other depending on which one. The unfortunate side effect of this is due to the shape of the holes, sometimes the motor can jump from one side of the snowman to the other, which is what causes the grinding. My team had this happen at an even this year. Luckily, since we had seen the issue when originally receiving and assembling the gearboxes, we were able to identify and remedy the situation within a few minutes.
Many teams have had issues with the grinding, but we used the WCP SS for a couple years (and then messed with them before season with them too) and have never had issues with the snowman circles. I know a lot of teams do, but it’s not every team.
Several of the posts in this recent topic deal with solutions or at least workarounds for the snowman hole problem.
The WCP SS gearboxes still interface with a VersaBlock given the WCP Gearbox bearing block uses a 1.875" bolt circle as well. We ran a WCP Gearbox this season in conjunction with a VersaBlock and had 0 issues.
Just to add onto your post, the problem is that if you’re using smaller pinions the gears mesh in either position, making the issue not immediately evident. You’ll probably get 20-30 matches until your pinions chew up the driven gear at the worst possible time.
That said, I believe most times this problem is due to installation errors, at least in my experience.
I’ve seen a few times where the motors are installed correctly, work fine for a few hours of run-time, then “jump” into the wrong holes. After that, the gearbox starts making a terrible noise and self-destructing. You can solve this by plugging the wrong holes and/or using a hose clamp or spacer block to hold the motors in position.
Does the “waist” of the “snowman” or CIM mounting screw show evidence of damage when they jump? Just curious. I know this is a real thing that happens, I’ve just never seen it personally.
I’ll be honest, I wasn’t looking so closely; I was more interested in making the repair and getting back on the field. But from what I do remember, there was at least some wear there.
These don’t work if you are running a wcd set up with 4in wheels Because of how low they sit.
We think we did alright using them in 2017. (link) YMMV.
How much ground clearance did you achieve?
Based on this drawing, there’s 1.6" between the center of the output shaft and bottom of the EVO slim. With a 4" wheel, that would be 0.4" of ground clearance.
That’s about what I was working with when I tried to use the Evo Slims in a WCD with 4 inch wheels. Unless the field was nearly flat like 2017, I probably wouldn’t be comfortable with that kind of clearance.
Same as the WCP gearboxes. I believe all these gearboxes has an option for a 60T output gear.
2017 was a flat field so it would be fine
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