Intake wheel motors

[JesseK]

The MiniCIM/CIM for Versaplanetary seems like a great way to go to get more power - except for a major factor (IMO). How do we accurately and cleanly cut the CIM/MiniCIM output shaft down to 3/8"? We once made a prototype with a MiniCIM/Versaplanetary, but wound up using standoffs from the adapter because the kids weren't able to figure it out at the time.

[jijiglobe]

Originally Posted by JesseK

How do we accurately and cleanly cut the CIM/MiniCIM output shaft down to 3/8"? We once made a prototype with a MiniCIM/Versaplanetary, but wound up using standoffs from the adapter because the kids weren't able to figure it out at the time.

Not exactly useful for every team because it requires a lathe but... we had an interesting solution.

We clamped down our CIM motor inside the lathe and then, instead of turning the lathe itself, we powered the motor directly from a battery. Lathes are not designed to be used on a shaft that's spinning quite that fast so it generated a lot of heat (make sure to oil it up). In the end it worked perfectly with the small caveat that the CIM shaft had burn marks on it.

[AllenGregoryIV]

Originally Posted by JesseK

The MiniCIM/CIM for Versaplanetary seems like a great way to go to get more power - except for a major factor (IMO). How do we accurately and cleanly cut the CIM/MiniCIM output shaft down to 3/8"? We once made a prototype with a MiniCIM/Versaplanetary, but wound up using standoffs from the adapter because the kids weren't able to figure it out at the time.

We wrap the CIM/MiniCIM in pool noodles then clamp it in our table vise. We use visegrips on the end of the shaft that is going to be cut off, then just hack saw through the shaft. We sand down the end to clean up any sharp edges after we are done.

[Deke]

You can run the versa planetary without modifying the CIM output shaft. I talked with Aren at vexpro, and the original intent for the CIM adapter was to leave the shaft unmodified. I do not remember the reason for them suggesting the modified shaft for normal usage, but we ran mostly unmodified CIM shafts with the adapters as shown below.

You have to leave all the stages in the gearbox for shaft clearance. We did have to shave off the end of the output shaft around .010"-.020" with a file to remove a minor interference.

We had zero issues with the setup for the 2015 season.

[AllenGregoryIV]

Originally Posted by Deke

You can run the versa planetary without modifying the CIM output shaft.

We found that that can work but it comes with some caveats.
1. Some CIM motors have the keyseat cut at the back of the output shaft, this makes it near impossible to have any amount of key in the input coupler to transfer toque unless you cut the shaft down some.

2. It adds a lot of length to the whole assembly.

[Deke]

Originally Posted by AllenGregoryIV

We found that that can work but it comes with some caveats.
1. Some CIM motors have the keyseat cut at the back of the output shaft, this makes it near impossible to have any amount of key in the input coupler to transfer toque unless you cut the shaft down some.

2. It adds a lot of length to the whole assembly.

You are correct. I forgot that we did have to sort through our CIM motors to find suitable keyseat flavors.

There were two reasons we didn't want to cut the shaft down.
1. To use the CIM motors for other applications later that required a normal output shaft.
2. With such a long assembly, we had a slightly improved side mounting with the input stage tapped holes kept in the assembly.

[Richard Wallace]

Originally Posted by AllenGregoryIV

We wrap the CIM/MiniCIM in pool noodles then clamp it in our table vise. We use visegrips on the end of the shaft that is going to be cut off, then just hack saw through the shaft. We sand down the end to clean up any sharp edges after we are done.

We've done this also, +1 for the recommendation because it works and it's fast.

Our 2014 Mini-CIM+VP intake can be seen in this picture; it is a straightforward rip-off of Team JVN's Build Blitz design.

Touch-it-own-it.

[bigbeezy]

Originally Posted by JesseK

The MiniCIM/CIM for Versaplanetary seems like a great way to go to get more power - except for a major factor (IMO). How do we accurately and cleanly cut the CIM/MiniCIM output shaft down to 3/8"? We once made a prototype with a MiniCIM/Versaplanetary, but wound up using standoffs from the adapter because the kids weren't able to figure it out at the time.

We clamped the motor in a vise. Held the shaft with vice grips and cut off the shaft with a dremel. Cut as straight as possible. My student took his time but really just eyeballed it. He then jsut filed the edges to remove any burrs. Didn't have any issues with it last year.

[Jared Russell]

Originally Posted by Ginger Power

Another tip for intake wheels when it comes to selecting the right gear ratio and motors: Your "intake velocity" aka the linear speed of your intake wheels should be greater than the max speed of your drivetrain. This makes it easier for you to intake a game piece while driving at it full speed.

As a huge fan of fast intakes on a team with a reputation for building fast intakes...

I've heard this rule of thumb parroted around a lot, but (in my experience) this can lead to teams building drastically undergeared intakes that stall at the first sign of trouble.

There is more that goes into a roller intake than speed, and high speed can bring with it some drawbacks. For most game objects that FIRST has given us, an effective intake requires carefully crafted geometry, materials selection, and deformation characteristics to work well. You may find that your mechanism is loaded in such a way during intaking that in order to prevent a stall when loaded AND run at a greater tip velocity than your maximum drive speed when unloaded would require a ludicrous amount of power. Or, you may find that a high tip velocity breaks static friction between the roller and game object when the robot isn't at full speed (i.e. most of the time).

It's really more of an impedance matching problem than a raw speed maximization problem (though adding more POWER to the equation usually helps). A lot of these tradeoffs are non-obvious and difficult to estimate from first principles, but can be the difference between a ridiculously effective and totally ineffective intake. Every team guesses wrong on total intake power and speed/torque from time to time. Unless you have the ability to quickly remake a custom transmission in-house, you really can't beat the VersaPlanetary for being able to quickly change your mind and adjust any or all of the power parameters of your mechanism.

[jwfoss]

When I think about fast robot intakes, nothing comes to mind more then FRC95's robot from 2002.

That being said, the RS775-18V will be greatly missed in the future for its size to power ratio. I'll all for throwing as much power as you can at an intake within the confines of weight and design. Looks like Mini-CIMs, BAGs, and 9015s for the future.

[Everett33]

Originally Posted by jwfoss

When I think about fast robot intakes, nothing comes to mind more then FRC95's robot from 2002.

That being said, the RS775-18V will be greatly missed in the future for its size to power ratio. I'll all for throwing as much power as you can at an intake within the confines of weight and design. Looks like Mini-CIMs, BAGs, and 9015s for the future.

Here is a video of their intake in action.
https://www.youtube.com/watch?v=jL6VtO5VSd8

[arc25565]

Thanks to everyone for all the suggestions. This has been very helpful.

[thinker&planner]

95 in 2002 looks amazing. But so does this.

[JesseK]

Originally Posted by thinker&planner

95 in 2002 looks amazing. But so does this.

Wow! Pretty amazing intake.

[Charger]

well, i learned it in a hard way but i can say that using andymark motors with gearboxes (like pg71) are a bit ineficient, in our aerial assist year we used pg71's in intake and it takes forever for it to get the ball totally. Last year we used window motors in our intake mechanism, it was better than pg71's but still it was too slow. However, this year, there was a special offseason event in Turkey with game of 2006, aim high and we built another robot for that offseason. In that robot we decided to use mini CIM motor connected to a CIMple box connected to wheels with chains and i can say that it almost worked perfectly. Still, bag motors with plenataries will probably be better but we dont have that much oppurtunutiy and parts in Turkey so we have never been able to test that.