Sonic Shifter - recent feedback?
 

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!

Re: Sonic Shifter - recent feedback?
 

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.

Re: Sonic Shifter - recent feedback?
 

I do not believe this is accurate. There is an output shaft for an encoder, but I don't think one comes included with the kit.

Beyond that, my 2cents when it comes to 2-speed gearboxes is to give VexPro a look. Their 2 CIM Ball Shifter (or even the 3 CIM Ball Shifter) is lighter than a Sonic Shifter, has a fully enclosed housing to prevent debris from getting into it, shifts more smoothly (in my opinion at least) than a dog gear due to the ball shifting mechanism, and will hold up through a whole season and beyond without any issues (if properly lubricated), and it's fairly easy to use an encoder with. Oh, and VexPro gearboxes are also quite a bit cheaper than AM gearboxes.

I don't have any particular problem with AM gearboxes, but when it comes to comparing two similarly functional and reliable products, lower weight and price always wins for me.

Re: Sonic Shifter - recent feedback?
 

Would you mind listing what the differences between them are?

Re: Sonic Shifter - recent feedback?
 

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.

Re: Sonic Shifter - recent feedback?
 

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

Re: Sonic Shifter - recent feedback?
 

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.

Re: Sonic Shifter - recent feedback?
 

Our history with the 3 cim ball shifter:

Re: Sonic Shifter - recent feedback?
 

Hmm, we haven't had any problems at all after 2 regionals and 2 offseasons with our 2014 bot and our 3 cims ball shifters.

Re: Sonic Shifter - recent feedback?
 

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

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.

Re: Sonic Shifter - recent feedback?
 

That looks really nasty, did you contact VEXpro.

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

Re: Sonic Shifter - recent feedback?
 

Three failures on different drive train sides isn't a coincidence. We ran that drive train hard as you well know (Central Illinois 2014). It was geared aggressively and we used (honestly, inadvertently) down shift motor braking constantly because of our automatic shifting routine in our programming.

It is my belief, the reason for the failure is primarily related to the fact that the shafts that carry the final stage reduction are cantilevered. In looking at the damaged gears it was apparent the failure propagated across the gear teeth, which indicates angular misalignment. That angular misalignment also would have occurred during the periods where the gears were under the highest load.

I do believe that had that stage been steel gears they might have tolerated the abuse, but to me, the ability for the shaft to deflect and allow that angular misalignment is a design flaw. I believe there are a number of features that don't promote a rigid configuration, but the cantilever is the largest problem.

We still use the drive train as a demo robot. We chose to modify the gearbox configuration to eliminate the cantilever and we haven't see another incidence of the failure to date.

Re: Sonic Shifter - recent feedback?
 

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.

Re: Sonic Shifter - recent feedback?
 

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.

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. :rolleyes:

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?

Re: Sonic Shifter - recent feedback?
 

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.

Re: Sonic Shifter - recent feedback?
 

Sorry for the thread jack, here is my two cents.

My personal opinion regarding AM's shifting products is that they are very robust and depending on your driving style worth the extra weight.

Steel gears are heavier, but stronger. This may not be warranted in some parts of a gear box where speeds are higher and torque is lower, but I believe it's a nice feature in the final reduction stages where you see the highest dynamic loads and you're transmitting the most torque.

In my FIRST career I've only had one type of failure from an AM dog style shifting gear box and that was due to mis-use It's important to regulate the pressure available for shifting down to the stated spec because that will damage the linkage connecting the pneumatic piston to the shifter shaft. It would appear this issue has been mitigated with shorter throw cylinders at this point.

Winch mechanisms circa 2010 are an example of how much abuse the mechanism will take. Many users were disengaging dog gears with several hundred pounds of force in play.

In comparison, I do like ball lock style shifters, because there isn't a force acting to disengage the shifter and shifting seems smoother to me.

These factors would drive the decision in my world.

Cost: Within 50 dollars of one another.
Safety factor: AM seems to have higher safety factors while VP designs are lower.
Weight: AM gearboxes are heavier while VP designs seem to be lighter.

I have my horror story. I've done a thorough analysis of why that happened and I'm confident in my understanding. Do I think most teams would encounter the same issue? No.

Also, I have some inherent bias. I have a number of good friends who are a part of Andymark, so no doubt it feels good to spend money there.

Ultimately you've got to use whatever gives your team the competitive advantage and fits your need.

Please implement automatic shifting regardless of which transmission you use. With the worry of brown-out and observations during 2014 with people blowing 120 amp breakers I think it's a must. Drivers generally don't use manual shifting when they should. It's hard to teach and takes a ton of experience to learn to use without hesitation. Ultimately in an intensive enough competition situation they will forget.

Re: Sonic Shifter - recent feedback?
 

We used 4 of them on our 2014 robot in a Mechanum setup. We haven't had any problems with them in 2 district events, district champs, 4 offseason competitions and a handful of demos. We haven't checked them for signs of wear but there are no signs of them breaking or showing age.

Re: Sonic Shifter - recent feedback?
 

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?

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.

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

-matto-

Re: Sonic Shifter - recent feedback?
 

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. :rolleyes:

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.

Re: Sonic Shifter - recent feedback?
 

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 ...

Re: Sonic Shifter - recent feedback?
 

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

Re: Sonic Shifter - recent feedback?
 

The decision was based not on pushing power, but a time to distance calculation that considered a two speed transmission. That pair of ratios minimized field crossing timed on a tool that was written up in Excel taking the two speed gearbox into account. People perceived 1747's robot as being tippy that year, specifically because of the brutal acceleration this setup generated. It was the one thing we didn't take into account and actually down-regulated our peak acceleration. No doubt the robot was quick across the field though. I personally think time to distance is an important consideration most teams neglect, but there are certainly some games where it's not a useful piece of data i.e. 2015.

We ended up machining a replacement for the shaft with a 1/2" round to sit in a bearing in a plate opposite the face of the plastic housing. The 3rd stage mounting plate wasn't used. The hole pattern was transferred onto our drive train plate. We haven't had a problem since implementing the modified shafts, which lends a great deal of credence to the theory that it was deflection in the cantilevered shaft that caused the failure.

The axle was supported with a bearing on the opposite side of the drive pod from the gearbox, so as long as the mounting of the gearbox was adequate the bearing in the face of the gearbox and the outer bearing we added should have picked up the load. I did forget to mention that we machined custom shafts from the get-go for the output of the gearbox. We needed a longer output shaft to span our drive pod. These shafts went to 4140 steel, instead of aluminum. Also, out of center might be a concern with a custom machined hex shaft. I verified they were centered prior to installation.

The automatic shifting code was very simple. Outside of handling for turning cases, there were two shift thresholds based on gearbox encoder feedback. I do not remember what drove the specific value used for down shift, but I think it was based on the highest speed that allowed enough separation between values to prevent oscillation between gears. The reason that the downshift occurred before full stop was in consideration of a number of logical conclusions about robot-robot interaction. The downshift feature did have one drawback. We had to have a specific case to handle direction changes, because the robot would end up on its back otherwise.

Just to clarify, my responses haven't been about "winning and argument" I'm just try to establish that we covered all of our bases as far as a well put-together investigation of the cause of the failure. It was actually a great exercise to be able to work through with my students. You can imagine in a competition setting there's a great deal of anguish caused by a failure of this magnitude in the student's eyes. It's a great feeling for them to be able to say, "This was not a flaw in our design, it was a failure of an input part. Here's why:"

-Charlie

Re: Sonic Shifter - recent feedback?
 

I agree with you that this can be an important parameter and we do calculate it, but it is game dependant. Sometimes that few tenths of a second gets you a game piece or allows you to avoid a defensive hit. There is always a lof of discussion on free speed, but I think time to X feet is a more relevant metric. Simbotics talks about it in their videos on strategic design and drivetrain design.

Thanks for the details on the design and fixes. Since we have never geared that aggressively, it is good to know some of the pitfalls in case we ever want to.

-matto-

Re: Sonic Shifter - recent feedback?
 

It is a legitimate approach, but will have more deflection than if the end of the shaft were supported. Is the difference in deflection sufficient to cause a problem? Sounds like it was in a few cases.

Based on your reply (and the comparison here) it sounds like there were a lot of design changes in the v2 Ball Shifter Shaft. Under what circumstances do you recommend teams replace this shaft? We just bought the upgrade, but have not installed it.

Re: Sonic Shifter - recent feedback?
 

I was wondering if someone from Vex would drop by this thread. Glad to hear this issue is an unusual/unique failure mode. Makes me feel better about our teams continued use of Ball Shifter Gearboxes (which as I've said already, we've been very happy with so far). ;)

Re: Sonic Shifter - recent feedback?
 

I would use the upgrade. The upgraded shafts are much better and allow for the use of the ThunderHex bearing without any additional machining.

By my math, the deflection difference is not enough to cause their problem. I believe it was related to a loose fit between the hex and shifter shaft in the v1 version of the ball shifter shaft combined with their increased load case.

Re: Sonic Shifter - recent feedback?
 

I bought several v1 Ball Shifters Transmissions when they first came out which are still unopened. We have yet to use them in our drivetrains, and used some of them instead for other robot features such as our winch for the ball launcher in 2014.
I better have them checked to possibly get the upgraded shafts.

Re: Sonic Shifter - recent feedback?
 

In 2013, we selected your team at the Boilermaker regional because we saw 1st hand what a 3 CIM drive could do on defense. After that 1 match where our robot almost got destroyed, I said we needed this team on our alliance.:)
Its nice to hear about your continued success in using the same setup in subsequent years.
However, I would respectfully disagree on the automatic shifting. We tried it in 3 different seasons and will never ever go back to it. In every instance, it failed/or started to wear heavily on some parts causing shifting problems. We got tired of the constant checking and paranoia that it would fail in a match.
We are aware of some of the issues that was discussed in this thread due to personal experience.
Modifications we have done in-house the past 2 seasons to our AM Supershifter, are using some VEXPro Aluminum gears and the pancake shifters instead of the ones that come with the AM or WCP ones.

Re: Sonic Shifter - recent feedback?
 

2 related questions as we consider the sonic shifter.

A.
One of the decisions related to AM super shifter or sonic shifter (vs. options of other vendors) is the different pneumatic actuator for shifting.

We've used both types of pneumatic actuators over the years and have not seen one to be more effective or more reliable than the other. Both types have worked fine for us.

Is there any advantage of pancake shifter (compared to typical cylinder required of AM shifters) other than more compact form factor?

B. Steel Gears vs. Aluminum

Aluminum saves weight and that can be a critical consideration. However, a bit of savings in weight is less important to us than robustness.

If weight is taken out of consideration, are the wear characteristics of aluminum gears (available by the typical robotics vendors) close enough to steel to be left out of the comparison pros and cons?

I'm not talking about outer-edge use cases, just a typical FRC shifting drivetrain for a game that has some pushing. (no automatic shifting). We've used both aluminum gears (in VEX products) and steel gears (in AM products) in past.

Re: Sonic Shifter - recent feedback?
 

The form factor, including the mounting, is the only real difference. If you use a COTS shifter, use the recommended cylinder. If you're building your own, managing space is the deciding factor.

It depends on how much pushing you're doing, and (more importantly) how hard the collisions are. The case where you're most likely to need steel is on the bull gear (gear nearest the wheel) and the gear that engages it. It would take a truly extreme case to require steel gears in the earlier stages, or even on the bull gear for simple pushing without collisions.

Re: Sonic Shifter - recent feedback?
 

Based on my conversation with Paul via email, I'd agree with the assessment that the press fit between the shifter shaft and the hex output shaft was the issue. I'd like to believe that with either the upgraded shaft, or our revision with the shaft being supported by a bearing opposite the gear we wouldn't have seen the failure in competition.

I'd be very curious to hear what those failure modes were with auto shifting and if there's anything I can add to that conversation. We implemented a power cut in the shifting routine that made a world of difference in testing and I suspect would significantly decrease .

I've been preaching autoshifting very hard given the fears about brown-out and the testing results we achieved with the robot in question in this thread from 2014. If the game warrants six cim two speed drivetrains this year, I suspect we'll see dozens of matches with dead at least one dead robot because of the brown out issue. I'm fairly confident, based on our experimental data, that a six cim shifting drive will brown-out if a drive accelerates aggressively from a stop.

Re: Sonic Shifter - recent feedback?
 

I second both these statements. I think the first stage in the gearbox is a great place for for aluminum gears.

One thing I've toyed with, but never implemented is the idea of removing material from the body of a steel gear to compensate for the weight differential. The strength of the individual tooth is really where the material decision has to be made. There are tools to make those calculations available.

In my FIRST career there are a number of things I've been conditioned to avoid because of bad experiences (none of these specifically from the three cim ball shifter situation discussed within this thread)

Aluminum gears, cantilevered shafts, and #25 roller chain are standouts on that list.

Re: Sonic Shifter - recent feedback?
 

I'd encourage any/all readers to avoid this "conditioning" approach.

If you want to win, steal from the best, invent the rest.

We (1678) have learned to use aluminum gears, cantilevered shafts, and #25 roller chain. We've learned mostly from Team 254 and VexPRO/WCP. These organizations have, between them, probably 10 of the best 50 mentors in the entire FRC program.

The best part is, for any reader out there, even if you are a freshman rookie in high school, these mentors are just an email or PM away. Ask 254 WHY they do cantilevered shafts every year and HOW they do it! Ask 1678 WHY we copy 254 and HOW we do it. Ask VexPRO/AM/WCP how to properly implement their products into your designs.

These resources are available. They are just an email away. You don't have to do any more guess work. You CAN be a better engineer by working harder and gleaning knowledge from people that have walked further down the path you are already on. Be encouraged that you are not alone, take advantage of the opportunities that are in front of you.

Learn from the best so you can BE the best.

-Mike

Re: Sonic Shifter - recent feedback?
 

Don't blame the parts, blame your implementation. Hundreds of teams have used all of these things every year without any problems whatsoever. The only time I've shredded an aluminum gear is when it was taking huge shock loads that were far more than the gear was ever supposed to support at the end of a very large reduction. My old team has used cantilevered driveshafts since 2011 without any failures. We have never failed a 25 chain in any case, even when undertensioned and slightly misaligned. Avoid what doesn't work for you, sure, but if you can't make things work that work for everyone else, you probably have bigger problems.

This is entirely conjecture. Properly aligned and sized for the application, in a drivetrain you should basically never fail an aluminum gear no matter how hard you're pushing. Maybe if your output gear is 14 teeth or something crazy like that you'll have a failure, but in normal applications you'll be totally fine.

Re: Sonic Shifter - recent feedback?
 

I agree with Chris - why not just run the numbers yourself instead of guessing? Here is a great presentation on shear stress in a spur gear. Matweb should have material info on 7075 aluminum and 4140 steel (not sure how to apply allowance for the ceramic coating on the aluminum gears). See what safety factor your teeth have for each gear in the gear train for each material. The less robust the mounting, the more safety factor is needed.

-matto-

Re: Sonic Shifter - recent feedback?
 

The ceramic coating is going to mostly effect wear characteristics that might otherwise be problematic in aluminum. Running the numbers is without question the way to make the decision. Ideally if you had the resources and time, you'd validate those calculations with actual load testing. I wish Machinery's would donate a copy to each FRC team. It'd make the world a better place.