Sonic Shifter - recent feedback?

[James3245]

If this year's game warrants a 2-cim shifter we will be considering AndyMark's "Sonic Shifter"

I read some earlier posts (2014). It would be helpful to have recent thoughts from users on how this product has been for:

-ease of assembly/installation
-operation
-reliability over time
-use of encoder (which I understand comes pre-installed)

Thanks!

[TylerS]

Are you locked into the idea of using the sonic shifter? Vex and West Coast products have options which are better than the sonic shifter in almost every way.

[Peyton Yeung]

Originally Posted by TylerS

Are you locked into the idea of using the sonic shifter? Vex and West Coast products have options which are better than the sonic shifter in almost every way.

Would you mind listing what the differences between them are?

[pilleya]

Originally Posted by Peyton Yeung

Would you mind listing what the differences between them are?

Both the WCP DS and the AM sonic shifter are dog-shifting style gearboxes.

An encoder can be fitted to the Sonic shifter out of the box, while a WCP DS does not, but a grayhill or CTRE mag encoder on an outer axle or a CIMcoder

In terms of weight the WCP DS, 2.92 Spread Kit with pinions weighs 1.93 lbs. The AM sonic shifter weighs 3.41 lbs with pinions.

The WCP DS is more compact than the Supershifter especially in terms of height.

There are 18 ratio options for the WCP DS. The Super shifter has 8 ratios options, but is capable of much lower gearing because of the inbuilt third stage. The WCP DS comes in a 3CIM version and the 3CIM is compatible with a PTO.

The WCP DS has 7075-T6 gears with teflon infused ceramic coating which is meant to improve efficiency.

Uses lithium grease for lubrication, not the fun red tacky grease as in the Sonic Shifter(because of lack of steel gears)

The Sonic Shifter can use a servo for shifting if required

The 2CIM WCP DS is $227.96 and the Super shifter is $279

[BoilerMentor]

Originally Posted by TylerS

Are you locked into the idea of using the sonic shifter? Vex and West Coast products have options which are better than the sonic shifter in almost every way.

Let me remind you that the very team you're mentoring this year had three, successive failures of the aluminum gears in the final reduction stage on three cim ball shifters. Including a pair of back to back failures that took us out of a one day offseason event we traveled 8 hours round trip for. I can assure you, based on that experience from 2014 we will NOT be using vexpro gear boxes in the drivetrain.

[Tom Line]

We've used the sonic shifters quite a bit - we used two in our drivetrain and one powering our winch. We had a comp bot and a practice bot, so we had 6 in all.

We abused the one powering our winch to the extreme: we knew we were pushing it FAR beyond the design envelope with the forces were were shifting it under. We upsized the shifting cylinder and removed a stage so we could shift it into neutral. We routinely loaded with with 200-300 pounds and were releasing it.

We expected it to break, and it did. The shifting pin sheared and the dog gear rounded off the ears and the pocketed slots twice during the season.

The drivetrain shifters were installed and used as they were meant to be. The did not fail at all. In the off season we went in and had to change out the dog gears because the ears had rounded off.

We used encoders on them and had no issues.

Used as expected, we would recommend the gearbox to anyone.

[James3245]

Originally Posted by Tom Line

We've used the sonic shifters quite a bit - we used two in our drivetrain and one powering our winch. We had a comp bot and a practice bot, so we had 6 in all.

We abused the one powering our winch to the extreme: we knew we were pushing it FAR beyond the design envelope with the forces were were shifting it under. We upsized the shifting cylinder and removed a stage so we could shift it into neutral. We routinely loaded with with 200-300 pounds and were releasing it.

We expected it to break, and it did. The shifting pin sheared and the dog gear rounded off the ears and the pocketed slots twice during the season.

The drivetrain shifters were installed and used as they were meant to be. The did not fail at all. In the off season we went in and had to change out the dog gears because the ears had rounded off.

We used encoders on them and had no issues.

Used as expected, we would recommend the gearbox to anyone.

This is helpful, thank you. Any other comments from teams with field experience with Sonic Shifter would be helpful. (We are already familiar through direct experience with several options from other vendors) I appreciate the input.

[PurpleInk]

Originally Posted by BoilerMentor

Let me remind you that the very team you're mentoring this year had three, successive failures of the aluminum gears in the final reduction stage on three cim ball shifters. Including a pair of back to back failures that took us out of a one day offseason event we traveled 8 hours round trip for. I can assure you, based on that experience from 2014 we will NOT be using vexpro gear boxes in the drivetrain.

Our history with the 3 cim ball shifter:

[pilleya]

Originally Posted by PurpleInk

Our history with the 3 cim ball shifter

That looks really nasty, did you contact VEXpro.

I can see why your reluctant to use a ball shifter again

[cbale2000]

Originally Posted by PurpleInk

Our history with the 3 cim ball shifter:

What lubricant were you using and what was the overall reductions in your drive system (including wheel size)?

IMO our 2014 robot put it's 3 CIM Ball shifters through far more abuse than the average team and the gears still look as good as new. For that matter, I've yet to see so much as a chipped tooth on any of the over 75 various Vex Pro gears we've used on competition robots in the past two years.

Originally Posted by Joe Ross

That's not what the Product Page says: Will be shipped with an am-3132 encoder pre-installed.

Good catch, not sure how I missed that, I did look at the page. Still getting used to the new AM site layout I guess.

Originally Posted by Joe Ross

If you consider the included encoder, and the fact that the sonic shifter does ratios that require the 3rd stage on the ballshifter, the price difference is much smaller. $215 for the ball shifter + 40 for an encoder vs 279 for the Sonic Shifter. Weight does favor the ball shifter.

True the difference is smaller in certain configurations, but still less regardless, and Sonic Shifters doesn't really offer anything the Ball Shifters don't also (save a few gear ratios perhaps), so if you can still save some money and weight, why not?

[BoilerMentor]

Originally Posted by cbale2000

What lubricant were you using and what was the overall reductions in your drive system (including wheel size)?

IMO our 2014 robot put it's 3 CIM Ball shifters through far more abuse than the average team and the gears still look as good as new. For that matter, I've yet to see so much as a chipped tooth on any of the over 75 various Vex Pro gears we've used on competition robots in the past two years.

Gear ratios were 18.75:1 and 7.08:1. Gearboxes were lubricated with moly grease containing Teflon. The gearbox direct drove a 6" x 2" wheel at the center of the robot which was chained to the other two wheel in the drive train side, also 6" x 2" wheels. All wheels were treaded with blue nitrile. Center direct drive shaft was supported with a bearing in the outer plate. Two other axles were dead shafts with bearings in the wheel.

The high load situation I believe created the problem was encountered when the driver returned the control stick to a neutral position with the robot at a high speed. The auto shifting code would have immediately tried to shift the robot to low gear with all three cim motors braking.

I've spent a fair amount of time "behind the glass" as it were. I'd challenge you to find a driver who pushed their robot harder and drove more aggressively.

I truly believe that we saw this failure because we pushed the design to its performance limit and shaft deflection leading to angular gear misalignment and ultimately gear tooth failure was the manifestion of that failure. If it had been on only one drive train side or it only happened one time I would write it off as bad luck, but that was not the case.

[aldaeron]

Originally Posted by BoilerMentor

Gear ratios were 18.75:1 and 7.08:1. Gearboxes were lubricated with moly grease containing Teflon. The gearbox direct drove a 6" x 2" wheel at the center of the robot which was chained to the other two wheel in the drive train side, also 6" x 2" wheels. All wheels were treaded with blue nitrile. Center direct drive shaft was supported with a bearing in the outer plate. Two other axles were dead shafts with bearings in the wheel.

I want to point out for folks who don't spend a lot of time looking at gearboxes that this is a very aggressive gearing with one of the highest CoF wheel tread materials. My quick calcs say this generates ~747 pounds of force at the wheel patch with 6 CIMs, well over the traction limit of 185 for a maximum weight robot in 2014. Meaning it is an extreme case and may not be the best one to guide the decision of an average team.

Overall this is great feedback. I have been wondering how the 3rd stage on the 3 CIM works at high loads. I always thought the sheet metal with standoffs 3rd stage looked a bit rickety. I am curious if you ever subbed out the 7075 aluminum gears for 4140 steel gears in the third stage of the 3-CIM shifter? Sounds like it was a misalignment issue more than a material strength issue. Did you ever try stacking on a second Vex third-stage plate to add stiffness to the third stage bearing? This would pickup more of the bearing race and possibly prevent angular deflection.

I am assuming the output of the gearbox was direct driving your center wheel in a tank drive. How do you think a 2 stage 3-CIM shifter would work if offset from the wheel axles and with a #35 chain reduction between the gearbox and wheel axles in lieu of the Vex 3rd stage?

Originally Posted by BoilerMentor

The high load situation I believe created the problem was encountered when the driver returned the control stick to a neutral position with the robot at a high speed. The auto shifting code would have immediately tried to shift the robot to low gear with all three cim motors braking.

Was there a particular reason for adding this "stop on a dime" feature? Did it work as you had hoped? Would you recommend it? It does seem like a recipe for gear teeth shearing.

Originally Posted by BoilerMentor

I've spent a fair amount of time "behind the glass" as it were. I'd challenge you to find a driver who pushed their robot harder and drove more aggressively.

Based on photos and gearing - I agree - you win!

-matto-

[cbale2000]

Originally Posted by aldaeron

I want to point out for folks who don't spend a lot of time looking at gearboxes that this is a very aggressive gearing with one of the highest CoF wheel tread materials. My quick calcs say this generates ~747 pounds of force at the wheel patch with 6 CIMs, well over the traction limit of 185 for a maximum weight robot in 2014. Meaning it is an extreme case and may not be the best one to guide the decision of an average team.

I second this.

Though that said, we used the same gearbox in 2014 with a 26.04:1 low gear and a 7.08:1 high gear on 4" wheels with the same tread.

Originally Posted by aldaeron

Overall this is great feedback. I have been wondering how the 3rd stage on the 3 CIM works at high loads. I always thought the sheet metal with standoffs 3rd stage looked a bit rickety. I am curious if you ever subbed out the 7075 aluminum gears for 4140 steel gears in the third stage of the 3-CIM shifter? Sounds like it was a misalignment issue more than a material strength issue. Did you ever try stacking on a second Vex third-stage plate to add stiffness to the third stage bearing? This would pickup more of the bearing race and possibly prevent angular deflection.

I don't think the issue is the plate stiffness, but the fact that the small output gear (the one with the missing teeth in the photo on the last page) is on a cantilevered shaft. If one was to modify the plate so that another bearing could be used on this shaft, there likely would not be any problem.

On a related note, our team actually did this recently with a pair of VexPro 2 CIM Ball Shifters that we had inadvertently ordered without the 3rd stage (and apparently the output shafts on the 2nd stage are longer when order it like this). So we made a pair of replacement plates so that the smaller 3rd stage gear could be retained by an additional bearing instead of having to remove the shaft and lathe a snap ring channel into it.

[aldaeron]

Originally Posted by cbale2000

I don't think the issue is the plate stiffness, but the fact that the small output gear (the one with the missing teeth in the photo on the last page) is on a cantilevered shaft. If one was to modify the plate so that another bearing could be used on this shaft, there likely would not be any problem.

On a related note, our team actually did this recently with a pair of VexPro 2 CIM Ball Shifters that we had inadvertently ordered without the 3rd stage (and apparently the output shafts on the 2nd stage are longer when order it like this). So we made a pair of replacement plates so that the smaller 3rd stage gear could be retained by an additional bearing instead of having to remove the shaft and lathe a snap ring channel into it.

Wow I had never noticed that the output gear is unsupported on the 3rd stage for both the 2-CIM and 3-CIM ball shifter. For the 3-CIM I saw the hole in the plate and assumed it was 1.125, but it is only 1.000. Perhaps Vex thought the extra bearing would over constrain the shaft? A rare miss by Vex. The being said, the gear separation is 84T, so you could add some of my new favorite part, the Face Bearing Mount.

I am curious if you mounted your wheel right the to the output shaft or if the shaft was supported? I would take the 3rd stage output shaft and put two chain sprockets on in, then pass it thru a VersaBlock and put the wheel on the other side of the tube for a WCD setup.

The more you learn ...

[Paul Copioli]

BoilerMentor,

Were you guys using the old ball shifter shaft without the pin in it or the new shaft?

I ask because the press fit in the original shaft would allow the deflection you speak of but the new shaft would most definitely not.

Also, a cantilevered shaft with the proper bearing spacing behind it is a perfectly legitimate design strategy especially with the cantilevered gear so close to the external bearing face.

Additionally, this is the first example of a failure like this that we have seen with the 3 CIM shifter so I really would like to get more information from you.

PM me if you would like me to email you.

Again, this failure mode is not normal in the typical 3 CIM ball shifter use case (even with your ratios you are within our normal use case).

Thanks,
Paul