We are looking to mount 2 Neos to a hooded shooter with no reduction. It would be easiest to direct mount the NEOs to the axle that holds the wheels that contact the ball. However, our mentors say that this will damage the motor bearings because of the harmonics and vibration of the shooter.
I have seen designs that go direct on CD, and WCP’s GreyT shooter has a direct drive option. Thus, does going direct lead to issues, or is it better to add a short belt run?
It really depends on what you want to do and how much clearance you need near the shooter. Im not exactly sure how direct drive messes up the motor bearings but for us all of our testing has been with direct drive NEOs and its worked fine for us. Personally I would go direct because it eliminates failure points involving the belt.
Depending on what you are trying to achieve for you game play strategy, you may find that the max RPM of a NEO with a 4" wheel might not get you the range you want.
Now, if you are using a larger wheel, then you should be fine.
If you design the system so that the radial forces on the flywheel are supported by the motor bearings then you’re likely to damage the motors. If you support the flywheel shaft well with other bearings and then have the motors on the outside of those bearings, you’re probably going to be fine.
Supporting the wheel on VersaPlanetery output shafts probably isn’t the best idea either in my opinion. Planetary gearboxes don’t like side loads on their output shafts. As the ball goes through the shooter the compression is putting radial loads on the shaft, which can end up binding and destroying the gearbox. It’s a lot safer to have the motor (and gearbox if necessary) separated from the external loads.
With Versa one to one you don’t have planetary gears. It is basically a coupling that isolates the motor from the side loading. So it is not as bad as you would think. I would prefer bigger bearings than what is in the Versa box, but this is an off the shelf solution. You will need to source a hex shaft coupler. I think AndyMark has them. GreyT uses this solution as one of the options on their shooter. Adam had more FRC cred than most of us. (I am not speaking for Adam and am not saying this is his recommended solution.)
Most problems that people have with overloading the output shafts is when they don’t have any support on the other side of the shaft. In that case, the output shaft will act as a lever and you will damage something. As long as you make sure to have a versaplanetary on either side (or just use a bearing on the other side) to keep the support even on both sides, you will be fine.
Even if the gearboxes can handle the side loads, you should consider other consequences of direct mounting the gearboxes/motors to the shaft – I think it will make replacing those shooter wheels more difficult than it needs to be. If you have to take the motors/gearboxes off when the shooter wheels degrade/accumulate “game piece” coating, as some have said urethane wheels will, the process for replacing them will be more difficult compared to doing a 1:1 belt stage or something at the end.
Yes, but without bag day restrictions this year, I do not think that will be a major problem. As far as I can tell, a set of 60A fairlane wheels should be able to easily last a full competition. Also, it would only be 2 bolts and 2 set screws to remove if you use a female shaft coupler and face mount the motor, so it wouldn’t be that bad of maintenance. I have students that could get the job done in 5 minutes flat if needed.
WCP has some wheels that are similar (practically identical) that have a hex hub in them already. You can also get them from mcmaster if I recall, but you will have to 3D print or machine a hex hub for those ones.
Using an hex coupling to the gearboxes… Just slide the couple on the shaft and the wheel comes off with gearboxes in place.
In terms of Hex adapters to wheel adapters… We machine ours. The down side is broaching the hex is best done a press that is not in your typical FRC work shop. 3D printing them is another possibility. (Adam suggested this in recent thread. ) I have not actually tried this, but the Vex hex hubs should press right in.