Al's Annual Inspection Thread 2013

[EricH]

Originally Posted by JVN

That is my interpretation, also.

The undefined rigid fastening system can be a heavy, rigid fastening system, as long as no other rules are violated.

-John

Aye, but here's the thing: He wasn't asking about a fastening system. He was asking about a backing system. Now, to me at least, the way the question was put indicates wanting to put a nice large piece of metal behind the plywood, in addition to the fastening system. Not as the fastening system, but in addition to it.

So, here is a question for you to answer (and may you have the right answer as the inspectors): If there is a heavy piece of metal, that serves no purpose in the fastening system or the bumper, and it is attached to the bumper, is it legal or illegal? Assume for the sake of discussion that the fabric is clamped using an obvious system not involving said piece of metal.

[FrankJ]

So, here is a question for you to answer (and may you have the right answer as the inspectors): If there is a heavy piece of metal, that serves no purpose in the fastening system or the bumper, and it is attached to the bumper, is it legal or illegal? Assume for the sake of discussion that the fabric is clamped using an obvious system not involving said piece of metal.

If it served no purpose to the fastening system, (just there to add stiffness / weight.) I would say that it is not legal. If it is an integral part of the fastening system then you have a good argument for it being legal regardless of the side benefit.

A side story, In the way back days of show room stock car racing. Some people came up with the idea of attaching the roll bars in such a way to make the chassis stiffer. (Bob Sharp cars driven by Paul Newman if memory serves me correctly) Competitors complained until they did the same thing to their cars. I am not trying to equate that to putting metal rods in bumper noodles.

[Al Skierkiewicz]

OK,
Let me try to restate this. Teams regularly come up with unusual bumper designs, some are legal and some are not. It is legal to add aluminum plate to the back of a bumper system to aid in easy mounting of the bumper to the frame. These are most often used in one piece bumper designs. The backing plate is also used to strengthen the bumper in addition to mounting. Backing plate is limited of course by the gap rule. 1/2" plate would obviously violate the bumper rules.
If the team adds something to the bumper to satisfy the supporting structure part of R29, then that weight is required to be part of the robot weight and not the bumper weight. The LRI at each event is trained to make that determination.
The illegal addition of weight which I stated earlier violates several parts of the bumper rules including the hard parts distance limit and unmodified pool noodles.
As to variations in weight. Depending on the materials in use on the robot, humidity plays a significant role from event to event. Also while it wouldn't seem possible, concrete floors do have some flexibility and therefore standing near to the scale can affect it's accuracy. That is why teams should be asked to step back from the scale during weighing. Scales are also somewhat temperature sensitive and so significant cold drafts at floor level can also affect readings. Inspectors should be aware of these variables and know how to accurately measure the weights of all robots. Calibration is checked at minimum every day with known 25 lb. standard weights.
BMartin, I hope this answers your question.
Everyone, a committee was formed last summer to investigate the bumper rules and try to make them easier to understand, more open to design and construction, better for rookies and in general to make it easy for all teams. The result was a recommendation to the GDC which accepted the report and incorporated that into the 2013 rules. Inspectors, veteran mentors and rookie mentors all had input.
On a personal note...I do not like ugly bumpers. I don't like to see flaps hanging down, bumpers that are crooked on the frame or have a sloppy mounting. Teams spend so much time making beautiful machines that look good in print and on TV. Why would you want that image spoiled by an ugly bumper system?

[Al Skierkiewicz]

OK,
Time to start thinking about the Championship and how your robot stand in terms of inspections. Every year we will find robots that had something sneak through in inspections, something missed by a new inspector or something added without being reinspected. So from here on, we will discuss some of those problems that we have seen this season and remind teams of some of the rules and how they are being enforced.

1. If I had a nickel for every time I heard "But we passed at XXXX regional" I would have retired a long time ago. We will find things that other events may not have. Sorry, but you are in the Big Show and everything will come under scrutiny.
2. Bumpers have not been the issue they have been in the past. The bumper committee hopes the new rules have helped with that. However, everyone really likes to see at nice looking robots. Please insure that your bumper covers look nice and don't drag. Strictly interpreted, the cover that hangs down to the floor is out of the bumper zone. I have seen several robots run over the covers while in match play. Please don't be one of them.
3. Frame perimeter issues should be all fixed by now but we will still check every robot.
4. Virtually of all of the later season events have had robots changing design or function throughout the weekend. I expect Champs to be the same. There are rules that limit your changes. A team can make design improvements whenever the pits are open. These modifications are viewed as improving robot function. However, if the improvement requires you to remove robot mechanisms in order to make weight, you may not return to the original design. This violates the rule that requires all mechanisms to be weighed at the same time. If the additions and robot are under the 120 lbs when weighed together, then the mechanisms are considered interchangeable and can be removed from match to match.
5. Make sure you have your Bag and Tag form handy when you enter the venue. I will have inspectors stationed in the pit aisles to make this a quick process. If your forms are not with the robot, make sure that one of the adults coming into the pits on Wednesday afternoon has the form. The one thing I don't want to do is hold up your opening while we get all the forms filled out. I don't know if the Head Refs will be reachable on Wednesday.

The division Lead Robot Inspectors will be Chuck Dickerson, Chris Paulik, Ed Sparks and myself. Jeff Pahl will miss this year but will hopefully return next year.

As an important note for teams using pneumatics. The robot rules are very specific as to the use of compressors. There may be one and only one KOP or equivalent compressor used to pressurize the robot. The compressor may be on board or off board but not both. You may not use a separate legal compressor to fill that tanks than the one you use on the robot. You may not use a shop compressor to fill the robot, ever. Head refs have been watching these practices. At a minimum, they may release stored pressure prior to the match starting. Please plan accordingly.

Until next time...

[CalTran]

Originally Posted by Al Skierkiewicz

OK,
2. Bumpers have not been the issue they have been in the past. The bumper committee hopes the new rules have helped with that. However, everyone really likes to see at nice looking robots. Please insure that your bumper covers look nice and don't drag. Strictly interpreted, the cover that hangs down to the floor is out of the bumper zone. I have seen several robots run over the covers while in match play. Please don't be one of them.

Quick random question about bumpers Al: What's the lightest full set of bumpers you've ever seen? We got inspected at Razorback with a full set of bumpers that weighed in at ~7.5lbs and shocked a great deal of inspectors with bumpers that defied all other bumper physics...our robot has a 108" perimeter, with a, IIRC, 14" gap somewhere and the rest is bumper. The color change for us was one of those nifty |-- shaped fabric covers where you lift it one direction or another for color.

[MechEng83]

Originally Posted by CalTran

What's the lightest full set of bumpers you've ever seen?

Our bumpers are the minimum size 8" corners. A full set (4 of them) weighed in at 7.1 lbs for each of our regionals. We have seperate red and blue sets, so we probably save weight over you by having less fabric. The attachments to the frame are some small aluminum c-channel brackets.

[Al Skierkiewicz]

7.5 lbs is about the lowest weight I have inspected this year. With the need to just cover the exterior corners, several were under ten pounds. However, the type of plywood used really is the determining factor. One team was nearly 18 pounds and was using exterior furniture grade 17 ply plywood. With all the resin and weather protection, the plywood is heavy. Anything over 15 lbs get a long look by inspectors to determine if any illegal weight has been added to pool noodle interiors.

Our bumpers are 90% full (cover everything but a few inches on the front and back of the robot), and a set of them is about 7.2 lbs. We used the normal 3/4" plywood and fabric. It's strong plywood and has never broken for us.

Is this normal?

[Jon Stratis]

I just checked for my two regionals... at Lake Superior, we had one set of bumpers that was 6.0 lbs, and at North Star a set that was 6.2 lbs. I can only imagine that both of those sets were corner-only bumpers!

[CalTran]

See, that's the thing - ours aren't corner only bumpers. I'll get the exact measurement tomorrow, but I believe we had somewhere around 90"-95" of bumpers, all your standard plywood regulation size.

[Al Skierkiewicz]

OK, some teams failed to bag their robot at their last event expecting to not get an invitation. Now that the invitation has arrived (and you have shipped your robot) this is a little bit of an issue. For all of those teams finding themselves in this situation, you need to contact FRC if you have not done so, to let them know. In addition, you will still need your B&T forms with you when you arrive.

[Wayne Doenges]

Originally Posted by Al Skierkiewicz

OK, some teams failed to bag their robot at their last event expecting to not get an invitation. Now that the invitation has arrived (and you have shipped your robot) this is a little bit of an issue. For all of those teams finding themselves in this situation, you need to contact FRC if you have not done so, to let them know. In addition, you will still need your B&T forms with you when you arrive.

Ooops

[Al Skierkiewicz]

I should add that if you did not bag your robot before putting it in a crate, then do not open it in St. Louis. Please see the LRI for your division when you load in your pit on Wednesday or Thursday. He will have specific info for you and will direct your team as how to proceed.