Ideas for Ball Shifter?

[JorgeReyes]

I am trying to see if there's away to make a 2 stage ball shifter with enough reduction to direct drive a wheel in a WCD. Does anyone know how to do this. I want to find a way to remove the 3rd stage reduction commonly used and make my gearbox lighter.

[Knufire]

You can swap to 11T pinions (P/N: 217-3107) on the CIM to get more of a reduction.

You can also direct drive a smaller wheel, such as a 3" Colson Performa.

Even then, you're going pretty fast.


If you're willing to machine gearbox plates, you have a bit more flexibility with ratios. VEXPro sells the shifting shaft separately.

[AdamHeard]

The initial reduction on the vexpro ballshifters is because their first stage is barely a reduction (they are just driving one of the pinions for the next).

This makes the package a lot slimmer. If you were to split the gears (similar to the WCP dog shifter) and put the first reduction between them (or not split them and put the first reduction in front or behind them), you'd be able to fit a full reduction.

[JorgeReyes]

But splitting the ball shifter gears or trying to put it in front or behind the inital reduction like dog shifters would require a custom ball shifter wouldn't it? If you split them you need to have to ball shifter holes farther apart which would mean maching a custom ball shifter housing and moving it in front or behind would mean machining a longer or shorter ball shifter rod.

I might just go with a dog shifter for ease of manufacturing.

[BBray_T1296]

The 3 CIM ballshifter has the 2nd Stage WCD addon, which made direct driving a 3" wheel a great option for us last year. We ran with all 6 CIMS with a ~5.5fps low and a ~15.5fps high, which was more than enough for our needs

[JorgeReyes]

I'm aware of the 3rd stage option but what I am experimenting with is if its possible to remove that extra 3rd stage add on in an attempt to reduce components (making it more simple) and possibly make it lighter.

Basically try to make it like a dog shifter but using a ball shifter.

[Bryce2471]

Originally Posted by JorgeReyes

But splitting the ball shifter gears or trying to put it in front or behind the inital reduction like dog shifters would require a custom ball shifter wouldn't it? If you split them you need to have to ball shifter holes farther apart which would mean maching a custom ball shifter housing and moving it in front or behind would mean machining a longer or shorter ball shifter rod.

I might just go with a dog shifter for ease of manufacturing.

Going with a dog shifter, is not a bad choice. But with a little design work, you should be able to use the cots ball shifter shaft. You would definitely have to make custom plates though.
If I were you, I would consider hanging the CIMs over the drive rail, and putting the cluster gear above your chain drive. (Or belts, if you prefer)

[asid61]

You can make a 1 stage shifter f you use 4 inch wheels and can machine a couple gears down to length.
Basically, have an 11t pinion and a 14t pinion on each CIM shaft and have them gear to two gears- a high speed and low speed gear. Then shift between the two gears.
That's a single stage version, but you can only get a spread of around 1.4x due to the maximum size of the gear being limited to the size of the wheel. Adding a second stage would allow you to have massive spreads.

[magnets]

Originally Posted by asid61

You can make a 1 stage shifter f you use 4 inch wheels and can machine a couple gears down to length.
Basically, have an 11t pinion and a 14t pinion on each CIM shaft and have them gear to two gears- a high speed and low speed gear. Then shift between the two gears.
That's a single stage version, but you can only get a spread of around 1.4x due to the maximum size of the gear being limited to the size of the wheel. Adding a second stage would allow you to have massive spreads.

I'm not sure that's really ideal. With an 11:76 in low gear and a 14:74 reduction in high gear, (same C-C distance with vex pinions), you get a 1.31 spread. On a 4 inch wheel (the gears have an OD of 3.9", so that's the smallest wheel you can get), you'll see free speeds of 13.4 and 17.5 fps, both of which will have you tripping breakers with 2 or 3 CIMs per gearbox.

You'd also need to find 76 and 74 tooth gears, and put in the hole for the bushing and the circular grooves for the ball shifter components.

[T^2]

I did this in the 2013 offseason. The drivetrain (WCD) worked out decently well for my team, but we ended up using a 3-stage ballshifter for the competition season.

[DampRobot]

Originally Posted by AdamHeard

The initial reduction on the vexpro ballshifters is because their first stage is barely a reduction (they are just driving one of the pinions for the next).

This makes the package a lot slimmer. If you were to split the gears (similar to the WCP dog shifter) and put the first reduction between them (or not split them and put the first reduction in front or behind them), you'd be able to fit a full reduction.

I've been hoping for a while that Vex/WCP will make a DS style ball shifter with 3 CIMs like you're describing. You could likely fit 3 CIMs around the cluster shaft, because you'd have more space for the gear the CIMs go around because there's no dog. That way, you could get a 3 CIM shifter with only two stages, which would make your gearbox a lot more efficient (and probably more compact and lighter) compared to a VP Ball Shifter with a 3rd stage. I'd guess the majority of teams would prefer to have the option of a more efficient gearbox that could do direct drive over a gearbox that was smaller, but needed an additional reduction before the wheels.

On the other hand, I can see why Vex wouldn't want to self compete, and the existing DS is already pretty good. I just see an opportunity for improvement.

[asid61]

Originally Posted by magnets

I'm not sure that's really ideal. With an 11:76 in low gear and a 14:74 reduction in high gear, (same C-C distance with vex pinions), you get a 1.31 spread. On a 4 inch wheel (the gears have an OD of 3.9", so that's the smallest wheel you can get), you'll see free speeds of 13.4 and 17.5 fps, both of which will have you tripping breakers with 2 or 3 CIMs per gearbox.

You'd also need to find 76 and 74 tooth gears, and put in the hole for the bushing and the circular grooves for the ball shifter components.

Whoops, I forgot about C-C distance.
Actually, you can put one shaft at an offset to the side for the low gear and put the high gear on the main shaft. You still shift between the two gears on the main shaft, but when you shift into low gear it could go through an extra reduction.
I will need to make a picture. Bascially, you have two pinions on the CIM shaft, but the 11t (low gear) pinion is mated with a gear on the side. That gear is on a shaft which connects to a small gear on the 2x1 side of the gearbox, which is mated with the main shaft. That makes a 2-stage reduction for the low gear, and a 1-stage reduction for the high gear.

[JorgeReyes]

Originally Posted by DampRobot

I've been hoping for a while that Vex/WCP will make a DS style ball shifter with 3 CIMs like you're describing. You could likely fit 3 CIMs around the cluster shaft, because you'd have more space for the gear the CIMs go around because there's no dog. That way, you could get a 3 CIM shifter with only two stages, which would make your gearbox a lot more efficient (and probably more compact and lighter) compared to a VP Ball Shifter with a 3rd stage. I'd guess the majority of teams would prefer to have the option of a more efficient gearbox that could do direct drive over a gearbox that was smaller, but needed an additional reduction before the wheels.

On the other hand, I can see why Vex wouldn't want to self compete, and the existing DS is already pretty good. I just see an opportunity for improvement.

Something I'm actually looking into is the possibility of using a DS upper cluster shaft to fit the initial stage reduction gear and the two other gears. Instead of having the initial reduction gear in the middle, it would be on the side closest to the cim motors and that way the two other gears are side by side and can work with the Vexpro ball shifter assembly. The vex ball shifter assembly would be one gear width in rather than being aligned with cim pinion gears. The only thing I that might work is the ball shifter assembly might not be long enough to fit properly in the side plate bearing.