Andymark Super Sonic shifters

[Crew Cox]

I was wondering if anyone has had any experience with andymarks's relatively new Super Sonic Shifters. My team was debating trying them out this summer and I wanted to know what exactly I'm getting us into. On the surface they offer an easy to assemble, presumably powerful, 3 cim gearbox without the hassle of making our own. Any thoughts would be greatly appreciated.

[BoilerMentor]

Originally Posted by Crew Cox

I was wondering if anyone has had any experience with andymarks's relatively new Super Sonic Shifters. My team was debating trying them out this summer and I wanted to know what exactly I'm getting us into. On the surface they offer an easy to assemble, presumably powerful, 3 cim gearbox without the hassle of making our own. Any thoughts would be greatly appreciated.

The Super Sonic Shifter doesn't represent the introduction of any untested technology, so I wouldn't expect performance or reliability outside of the realm of what has been observed with any of AndyMark's other shifting products.

[cbale2000]

I'm partial to the VexPro 3CIM ball shifters myself. They're cheaper (by $70 or more), in all likihood lighter, and have more reduction options.

[kyle_hamblett]

Having used the 2CIM sonic shifters, I can say that they perform with no issues. We have 4 of them on our 2014 bot that have not caused a single problem from the first match of 2014 up until driver practice this year. I can't imagine the 3CIM variant being much different.

[Crew Cox]

Thanks guys, kinda confirming my suspicions

[BoilerMentor]

Originally Posted by cbale2000

I'm partial to the VexPro 3CIM ball shifters myself. They're cheaper (by $70 or more), in all likihood lighter, and have more reduction options.

YOU AGAIN!?!?!?

Just kidding. Lot of folks have been breaking gears in the final stage on the VP gear box this year, even with the fix to the interface between the shifter shaft and the hex shaft. They're probably alright if you play it pretty safe on gearing, aggressiveness of control outputs, and driver behavior (good luck with that last one). If you're looking at anything near the edge of the performance envelope for FRC applications, I might be a little wary. Those gears can be swapped for their steel counterparts, but I'm not really savvy to that process. I'm developing a theory about these failures and I think it has to do with the elastic range of the gear material and shock loading in the drive train, because while similar in strength 7075 aluminum isn't as tough as 4140 steel.

If you're looking at an off season project, have you considered designing your own gearbox? It's not as hard as it sounds and people have found ways to make things exceptionally compact. I personally don't feel like any of the options on the market are particularly small. If you have any questions along those lines, I'm happy to help.

[Connor McBride]

We used the Sonic Shifters and needless to say, we broke some gears in half. In my own opinion, they're not worth the money. I'd go the Vex route.

-Connor

[chrisfl]

Originally Posted by BoilerMentor

YOU AGAIN!?!?!?

Just kidding. Lot of folks have been breaking gears in the final stage on the VP gear box this year, even with the fix to the interface between the shifter shaft and the hex shaft. They're probably alright if you play it pretty safe on gearing, aggressiveness of control outputs, and driver behavior (good luck with that last one). If you're looking at anything near the edge of the performance envelope for FRC applications, I might be a little wary. Those gears can be swapped for their steel counterparts, but I'm not really savvy to that process. I'm developing a theory about these failures and I think it has to do with the elastic range of the gear material and shock loading in the drive train, because while similar in strength 7075 aluminum isn't as tough as 4140 steel.

If you're looking at an off season project, have you considered designing your own gearbox? It's not as hard as it sounds and people have found ways to make things exceptionally compact. I personally don't feel like any of the options on the market are particularly small. If you have any questions along those lines, I'm happy to help.

Designing a gearbox offseason is something I'm interested in but I have no experience designing a shifting gearbox. I'm not 100% sure on how they work but I have a pretty good idea. Can someone explain the method of how one works and maybe help provide some tips for designing one? After really bad luck with the vexpro ss gearboxes, I think our team wants to design our own.

[pmangels17]

Most shifting gearboxes have this basic structure (this schematic might be helpful):

- The drive motors all drive a single gear on what many call the cluster shaft.

- The cluster shaft has two other "cluster" gears on it. All three of these gears turn together.

- The two cluster gears drive the two gears on the shifter shaft (in this case, they have a profile in their side to accomodate a dog, or, alternatively, a different profile for the ball shifter). These dog gears spin about the shifter/output shaft, but they are not mechanically linked to it. This is because they are spinning at two different speeds, as each dog/cluster pair has a different gear ratio. Instead, these dog gears have bearings in them to let them spin freely.

- A dog (or ball shifter equivalent) is mechanically linked to the shifter shaft by a hex profile on the shaft (like a hex hub sliding on a hex shaft). The shifter shaft is hollow, so a small rod coaxial to the shaft(usually attached to a pneumatic cylinder) is linked to the dog. By sliding the dog back and forth along the shaft, you can select which dog gear it engages, effectively controlling which cluster/dog ratio is engaged with the shifter/output shaft.

-sometimes, depending on how you plan to deliver power to your wheels, a third stage gear reduction is added after the shifter, but this isn't always the case.

This is the standard practice used on the AndyMark, VexPro, and WCP shifters, as well as many shifting gearboxes that various teams have designed and built themselves, but many adaptations and variations have been developed. Team 192 comes to mind as having some really gorgeous, non-conventional gearbox designs.

[chrisfl]

Originally Posted by pmangels17

Most shifting gearboxes have this basic structure (this schematic might be helpful):

- The drive motors all drive a single gear on what many call the cluster shaft.

- The cluster shaft has two other "cluster" gears on it. All three of these gears turn together.

- The two cluster gears drive the two gears on the shifter shaft (in this case, they have a profile in their side to accomodate a dog, or, alternatively, a different profile for the ball shifter). These dog gears spin about the shifter/output shaft, but they are not mechanically linked to it. This is because they are spinning at two different speeds, as each dog/cluster pair has a different gear ratio. Instead, these dog gears have bearings in them to let them spin freely.

- A dog (or ball shifter equivalent) is mechanically linked to the shifter shaft by a hex profile on the shaft (like a hex hub sliding on a hex shaft). The shifter shaft is hollow, so a small rod coaxial to the shaft(usually attached to a pneumatic cylinder) is linked to the dog. By sliding the dog back and forth along the shaft, you can select which dog gear it engages, effectively controlling which cluster/dog ratio is engaged with the shifter/output shaft.

-sometimes, depending on how you plan to deliver power to your wheels, a third stage gear reduction is added after the shifter, but this isn't always the case.

This is the standard practice used on the AndyMark, VexPro, and WCP shifters, as well as many shifting gearboxes that various teams have designed and built themselves, but many adaptations and variations have been developed. Team 192 comes to mind as having some really gorgeous, non-conventional gearbox designs.

So there are two different gear ratios both being driven at the same time. The gears on the output shaft spin freely and the dog moves back and forth to engage one of the output gears to the shaft?

[chrisfl]

Thank you for helping

[cbale2000]

Originally Posted by BoilerMentor

YOU AGAIN!?!?!?

Just kidding. Lot of folks have been breaking gears in the final stage on the VP gear box this year, even with the fix to the interface between the shifter shaft and the hex shaft. They're probably alright if you play it pretty safe on gearing, aggressiveness of control outputs, and driver behavior (good luck with that last one).

What can I say, the Ball Shifters have been good to us and I hate to see them get a bad rep.

Honestly I have no clue how some teams are having such difficulty with the final stages, we run our drives pretty hard but the most "wear" we get on our gears is dirt buildup; clean it off with a brush and they look good as new.
I can only assume that some teams are either improperly lubricating the final stage gears or something specific to their implementation is causing an issue, because in the 3 years we've used them, we've had zero problems.

Comparatively, I've have had a number of Andymark gearboxes (Toughboxes, and Super Shifters, though more-so the Toughboxes) over the years that have had their Steel gears grind down and wear out during competitions; consequently, between that and their higher weight we basically never use them anymore. Nothing against Andymark, we buy lots of other stuff from them, I just like the VexPro Gearboxes better.

[pmangels17]

Originally Posted by chrisfl

So there are two different gear ratios both being driven at the same time. The gears on the output shaft spin freely and the dog moves back and forth to engage one of the output gears to the shaft?

Exactly. The difference between ball shifters and dog shifters is the method used to engage the gears to the output shaft. The dog is simple, just three teeth that engage the three teeth and/or cutouts on the dog gear. I am not exactly sure how the ball shifter works, I'm pretty sure it is the same idea but instead of a dog there are three ball bearings that slide in between the different gears. The ball shifter method is slimmer, but I like the dog shifter method because it seems simpler to me.

EDIT: If you're curious as to how they work, I think you can buy a ball shifter shaft with a couple of the matching gears for not terribly much money, and you can do a similar thing for a dog shifter shaft and the matching dog and dog gears.

[InFlight]

We used both Vex ball shifters and various Andy Mark fixed and shifting gearboxes over the past few years. They both work very reliably.

The choice for us often comes down to the available ratios and the size of tires we are using that year. The Andymark 4:1 and Vex 3.65:1 are great options. We like having ~ 16 ft/s on the high end, and as low of a pushing gear as we can get.

The only downside of the Vex gearboxes is the indirect encoder mounting with plastic gearing. With the AM gearboxes it's easier to 3D print an encoder bracket and use any encoder you like.

With either shifting gearbox (3 stage vex) or any AM it's trivial to make custom output shafts on a lathe with 7075 hex stock.

With all of them, attention to detail during assembly and liberal use of grease goes a long way.

[pmangels17]

I think my previous post might have come as me knocking ball shifters or the VexPro gearboxes. This is not the case, I just don't have any experience working with them, so I can't comment one way or the other, though many teams absolutely love the ball shifters. All the shifting gearboxes I've worked with have been dog shifters, and I like how simple they are to put together, use, and troubleshoot if necessary.