After reading through threads here on Chief Delphi, our team (1569) is concerned about our open wheel shooter. What have been the difficulties regarding open wheel shooters, and which part of the wheels need to be covered to be considered safe?
I will also upload a photo of it tomorrow, or check out the video of our robot on YouTube.
We had no issues with our open-wheeled shooter at FLR… But our wheels are solid rubber 6" Colsons. I can’t speak for others with different wheels.
I covered this from my Hub City experience in Al’s annual inspection thread; see http://www.chiefdelphi.com/forums/showpost.php?p=1242728&postcount=30 and http://www.chiefdelphi.com/forums/showpost.php?p=1242765&postcount=32
Bottom line – wheels got covered on every robot.
Like many things, the answer is “it depends”.
I’m sure I’ll get to look at lots of unshielded shooter wheels in the next few days. My feeling on the subject is that any moving parts that extend outside of the mechanism such that they could catch clothing, hair, fingers, etc in the pits, or that could make contact with another robot or the field while on the field, will need to be enclosed. Obviously, you can’t cover the part of the wheel where it makes contact with the disk, which hopefully is within the mechanism and is reasonably enclosed.
Again, “it depends” on the exact implementation of the mechanism in question and the opinion of the LRI at any particular event. I fully anticipate this being the “headache issue of the year” at Championship, and my advice would be to err on the side of caution and safety.
We’re getting materials together to put a quick shroud around our small wheeled shooter at Lone Star. Some ABS sheet and a plastic bending heater strip. I’m assured it’ll take all of half an hour to cut, bend, and mount the plastic.
No open wheeled shooters had to be covered at FLR (us included), from what I observed.
Thank you, and these are the exact threads an posts I was referring to. We are planning to build a shield, just to be cautious, and adjust it as needed when we get to regionals. My final question, do the front of the wheels need to be covered, or just the side and tops?
It would be great if FIRST would provide some guidance on this issue so that there is a uniform standard (as much as possible) at all competitions.
I will be inspecting in Seattle and Calgary, and while the Lead Inspector is the one who gets to make the final call, I’ll certainly be looking for mechanisms to ensure that fingers, hair or other unexpected objects are not likely to come into contact with the wheel. Based on my experience in previous years, I expect to be able to reach agreement with most teams on what is reasonable. No one wants an unsafe robot.
One thing that I really liked was the plan for a team to bring ABS and a strip bender… perhaps teams that have the resources will set up a “shielding shop” to help less well-resourced teams improve their robot. Even 1/16" polycarb is likely enough to keep fingers out, and it can be cut and bent relatively easily if you’ve got access to the material and tools.
Jason
That depended on the existing design. There were some bots that only had a tiny bit of wheel uncovered in the front; we left those alone. Others had huge percentages of a wheel exposed; those were covered. Unfortunately, it’s an “it depends” situation.
This wasn’t just an “in case the wheel starts disintegrating” thing. One team had a wheel from a baseball pitching machine. It was factory-balanced and rated for some unearthly number of rpms. It got a cover.
One of the mentors for a team I was inspecting verbalized a great thought test for this. Ask yourself: would you be comfortable with this spinning at full speed with you and the bot in a phone booth? Both he and I are old enough to remember such structures; others may need to use Wikipedia.
I am going to agree with this whole-heartedly. Last year, there were very very few guards that I saw around any shooter wheels. We ran ours at 4,000 rpm, not much different that what we’re running this year.
Yet this year (per the first post), some inspectors are enforcing that they must be guarded.
I understand full well the difficulty FIRST faces in attempting to write rules. However, in this case, we have polar opposites going on at regional competitions. That’s confusing, and for a robot who is right on the edge weight wise can be extremely distressing. Please FIRST, put out a rules update stating that the outside of all shooter wheels must be covered. Bite the bullet and let everyone know now so they can plan.
At my regionals, my default position will be to require covers over all shooter wheels. It is up to the team to convince me that the danger of caught fingers/hair/clothing is acceptable, and that the wheel won’t suffer from sudden and catastrophic failure (for example, the rubber tire on most of these pneumatic wheels could easily stretch and come off at an unexpected angle during a match).
The best route to convince me will be a datasheet from the manufacturer that specifically lists an operating range that includes the speed your running the wheel at. Good luck finding that… even AndyMark’s pneumatic wheel states “The design intent is to be contacting the ground, being driven by a gearbox at a maximum speed of approximately 500 rpm”.
Given that statement, running the wheel at 10 times its intended speed, with variable and sudden loading on it from shooting, I **WILL **require appropriate safeguards placed around the wheel.
This will probably tick off several people but I have two words concerning guarding: Common Sense
You have a wheel turning at 5000+ rpm in the pit and it self destructs or someone accidentally drops a tool in it or someone gets too close. Would you want to call someone’s parents and explain how their child was injured because you didn’t guard the wheel?
If this made someone angry, I apologize.
Agree - this falls into two basic life rules -
Trouble is wheel guarding is anything apparently anything but “common sense” True guarding would prevent any chance of being able to touch a wheel while it is moving. Sort of like an OSHA approved coupling guard. The guarding you need for protecting the wheel is a lot different than what you will need for when the wheel shatters.
Common sense would tell you to keep the pit area clear of any non essential people especially visitors. Guarding in the pits should include any mechanism capable of sudden movement, pinch points, etc. I think this would impact the overall goal of First if we went fully down this road.
I am not really arguing the need to properly guard rotating components. I do think there needs to be more published guidance from First & not left up the event’s lead inspectors discretion.
PS I think this needs intelligent discussion without the need for flame suits. 
Here is a photo from Frank’s blog of some “great robots” at BAE tournament practice day. Presumably they passed inspection.
you are correct Gregor. We never had to put a shirld on ours. In fact we use to have a shield over it but took it off because there were more pinch points with the shield. If you just have a wheel then you are less likely to get hurt, if you have a shield over it you have 10X more pinch points. If you were to put your finger (please don’t do this!) into the shooter wheel at full speed your finger is likely to just bounce away, maybe get scraped. you may get your finger turned around the wheel a few times (as long as you don’t have something across the wheel stopping your finger). If you were to have a cover that has holes in it then if you were to put your finger in it your finger would get pinched and broken off (likely). If you were to put it in between the tread and outside of the guard you will get your finger pulling in and ripped off. I don’t see how putting a guard on your shooter wheel will protect you at all. Another reason we took it off was because while testing our tread ripped off from the guard and jammed up the shooter wheel, which if I left the shooter turned on the motor could have possibly burned, and possibly started a fire.
I don’t see how putting a guard on can possibly make the shooter wheel safer… The only thing it would help with is stopping tread from flying out, which while on the field won’t hit anyone because the field is enclosed.
Nobody even mentioned it to us as a possible concern at FLR. Then again, with solid rubber 6" Colson wheels on our shooter, the probability of their experiencing some kind of structural failure approaches zero.
I don’t know of any Hatboro Horsham robots that had to put on guards. We certainly did not.
I’ve Q&A’d a request for more guidance. (Not that I have overly high hopes) We’re squeezing ounces, but we certainly want to be safe (and legal). A “finger guard” is doable if useful, but if LRIs feel that shatter guards are necessary, that could be some serious practice night rework (and weight). What is the guard intended to actually do, and how can it best do so while avoiding pinch points?
We were never told it either, and we were running the new Nylon VEXPro Traction Wheels
I would like to see an official response/Q&A from FIRST on this.
