First off I know we should’ve figured this out by now but our team is running behind. Has any team figured out if it is inherently wrong to run your motor one-to-one for a shooter? We plan in using 1 neo driving each wheel on either side of the linear shooter (so 2 neos total). Our team is planning to run 1:1 but I am Advocating for a gearbox (Such as the flyer Andy Mark). What has been your experience observations From running 1:1 gears? Thanks in advance from a desperate team
The ratio you want will depend on some other variables, such as wheel size, compression, length of hood, shooter height, release angle, how far you want the ball to go, etc. You really need to put something together and see what happens.
@MrForbes is right. There are a metric ton of variables that affect how well your shooter will perform, and most of them can affect one another in unexpected ways. The best way to know if your setup will work is to test it.
That being said, there’s nothing inherently wrong with using a 1:1 “ratio” with a NEO motor. Just make sure that you’re properly supporting the wheel shaft with bearings and not using the motor to support the shaft, because this can damage the motor when the ball’s compression puts force on the motor shaft.
@AriMB has it right. We did this for our Stronghold shooter, which was a linear shooter with two horizontal wheels. They were each mounted 1:1 on miniCIMs with relief bearings on the shaft to prevent lateral strain on the motors. It worked just fine, and that was shooting the larger and heavier (though similar composition) Stronghold balls.
thanks for the info! Should we consider the gearboxes because that will allow us to change ratios very quickly(Compared To rebuilding the shooter every time we need to change).
It might depend on how you build the thing, if the motor is in line with the axle that the wheel is on, or if you have them parallel but on different axes, then you can use a belt or chain. If you set it up so you can use different (or the same) size sprockets or pulleys, you can adjust the drive ratio relatively easily. But we can’t see your robot design, so it’s hard for us to say.
We used the Rev 21-1650 neo’s (2) on the 1/2" Hex shaft(s) (2), through a Vex Pro1:1 gearbox (2) with a little machining magic by Magic Machinist George Williams, to (2) 6" Traction Wheels and 1.5"- or 3 treads wide with a little inspiration from team 4738. (Getting rid of the extra wt. of the (4), 52 tooth gears theirs used), but wheels, treads, Alum. hubs, 1/2" PVC Gray Spacers cover the hex axles between, 1" X 2" X 1/8" box Alum. tubing welded frame holds it all together along with a couple of motor/gearbox mounting plates.
A ball centering or indexing box utilizing (4) 1/2" hex shafts, bearings, sprockets, chain and a mini-CIM and a ball centering ring between the box and the shooter wheels delivers our catepillar of energy cells to the 26 degree tilted shooter assembly wheels.
The end squeeze on the ball is a very drastic but very effective 3.20" wheel-to-wheel spacing, or a bit over 50%.
We were going to have the shooter be a 2 position shooter pneumatically set assembly (19 Degrees long shot, 30 plus degrees close shot), but opted once we could get to 26 degrees tilt, fully inside our lil’ package. (But, after some brief but very tunable testing from out far at 40 plus feet to 50 feet or more, at just 19 degrees tilt), we decided to just mount it fixed at 26 degrees of tilt, and use upper and lower wheel speeds to tune the distance, amount of loft, velocity, and accuracy for each chosen shooting distance to upper high and tight. Limelight targeting is coming along well.
The NEOS are very fast to recover, so no over the top flywheel is planned to be used at this time, not that a safe one cannot be added in the future, but a strict diet of much drilling and/or machining elsewhere on our lil’ package would need to commence first. And there is no time to diet further currently.
Brushless motors addition(s) by FIRST as legal motor choices has been a very welcome addition with 7.25" energy cells. (Now if they just made a full field shot legal again…). It would be fun to try, but 10’ less is good too!
The real question on everyone’s minds right now, is…Is that top scoring 13" circle high and tight lexan tunnel those energy cells pass through to the ABS box shaped energy cell laser counter, able to really handle 5 cells shoved down its throat in as rapid a succession as the rate I have seen tested, as most are shooting through the hole into black plastic or just simply air? (After very real careful study, it looks like at a rapid succession, only ablout 3 balls may fit before trouble soon develops, and I guess only time will tell!)
Sorry to disagree, but the Stronghold boulders were elephant skin surface…Nothing short of a porcupine on this planet, is anywhere near similar to this years Rhino skin energy cell skin.
It appears by far, the most difficult design issue presented as yet by FIRST as a game pc, in the numbers that it will be utilized in, and the minimized space it is used in, to design for the movement of those game pcs. (1 boulder vs. 5 energy cells…I say thank the lord for gravity and sweet vibrations!)
Those things like to lock up to each other like super glue if you cannot keep them separated or attempt to push them together.
Okay, but what does that have to do with running the actual shooter wheels directly from the Neo motors as @T_H_E is proposing? This thread didn’t have anything to do with feeding the PCs into the shooter, which is a problem I’m sure they’re solving a different way than we did for Stronghold, since that was a system restricted by the rules to one ball at a time. That doesn’t make what they’re proposing for their shooter any less effective, as long as they make sure to do what I and others have recommended, which is make sure they have bearings supporting the motor shafts on the shooter motors to relieve stress. My point was that directly driven shooter wheels can work just fine, even with larger and heavier balls (which are of a similar composition, being skinned foam of a not too different density), which was the point of mentioning our Stronghold experience. This was all about what the motors can take, not anything else.
I want to reiterate what Jim has said.
Rather than building a completely different set of gearboxes to change ratios, it is much easier to change different size sprockets or pulleys (chain or belt) to get the desired speeds you want on your shooter. A built in tensioner helps you modify those changes much easier.
We just tested a two wheel shooter today, one 6" wheel was powered by a belt/gearbox combo and the small 2.5" wheel was directly driven by a gearbox. It worked well and you shouldn’t have any problems after testing and tuning.
If you do this, a single stage would likely be enough. AndyMark’s new Flyer gearbox is well suited to this task, allowing you to shift up or down (or 1:1) without changing gross geometry. I believe Vex’s single stage clamping gearbox would also work.
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