Pyramid variation

[dcarr]

Now that we've gotten through two weeks of regionals, I wanted to see what folks have been noticing in terms of variation of height on the competition pyramids. I've seen stray posts here on CD, Facebook, etc. claiming 1" or more of variation, but I want to confirm if such findings are true. Please share any measurements or observations you have.

[tim-tim]

Palmetto pyramids were within 3/8". That is a typical tolerance for most FIRST fields. Some of the variation was probably due to the flooring underneath. You could see a gradual change in elevation in the carpet when on the field.

We try to keep these type of tolerances in our design. Call it "room for error". We typically expect up to a 1/2" difference in field vs drawings. Overall though the two pyramids at Palmetto on the field and the practice pyramid were within "tolerance".

[EricLeifermann]

Originally Posted by dcarr

Now that we've gotten through two weeks of regionals, I wanted to see what folks have been noticing in terms of variation of height on the competition pyramids. I've seen stray posts here on CD, Facebook, etc. claiming 1" or more of variation, but I want to confirm if such findings are true. Please share any measurements or observations you have.

The pyramids at Northern Lights were 28 5/8 in from the bottom of the bar to the floor.

[dcarr]

Originally Posted by EricLeifermann

The pyramids at Northern Lights were 28 5/8 in from the bottom of the bar to the floor.

The official measurements dictate 30" to the center of the bar, right? So in fact, this was only 0.625" out of range if I understand correctly. Still not too bad.

I'm looking to see if there are any documented cases in which the pyramid was dramatically off (i.e. close to or greater than 1")

Our practice pyramid is about 3/8" off on the bottom, which I'm assuming (hopefully correctly) is within the range that could be expected at a competition and what we should be able to handle.

[Ekcrbe]

Originally Posted by dcarr

The official measurements dictate 30" to the center of the bar, right? So in fact, this was only 0.625" out of range if I understand correctly. Still not too bad.

30" to the center minus a 3/4" radius is 29-1/4" to the bottom of the bar, so it was low by 5/8".

Section 2.1 Overview
Fit and tolerance on large assemblies (e.g. the LOW GOALS) are ensured only to within ¼ in.

That would be 3/8" out of the tolerance range.

[fox46]

The problem we have been grappling with is that the pyramid pieces all "slide" together and there are no pinned connections between the assembled sections. During climbing, the sections pull apart and the pyramid turns into some sort of phsychadelic rhombus. This has been especially evident in our case as we induce a significant cantilevered load off the side of the structure. The reaction of the FTA/Field staff seems to be a shrug of the shoulders. It has been a dissappointment for us thus far and has forced us to rework several parts of our climbing mechanism to deal with the variation. A cordless drill, hammer, drift and some roll pins would go a long way here.

[Daniel Brim]

We measured as low as 28-3/4 at Orlando.

[tim-tim]

Originally Posted by fox46

The problem we have been grappling with is that the pyramid pieces all "slide" together and there are no pinned connections between the assembled sections. During climbing, the sections pull apart and the pyramid turns into some sort of phsychadelic rhombus. This has been especially evident in our case as we induce a significant cantilevered load off the side of the structure. The reaction of the FTA/Field staff seems to be a shrug of the shoulders. It has been a dissappointment for us thus far and has forced us to rework several parts of our climbing mechanism to deal with the variation. A cordless drill, hammer, drift and some roll pins would go a long way here.

To be fair, FIRST was upfront with how the pyramid was assembled. It's not like it changed over the season. Adding something now could affect many other teams.

[fox46]

To be fair, FIRST was upfront with how the pyramid was assembled. It's not like it changed over the season. Adding something now could affect many other teams.

So the pyramids are supposed to come apart during game play and any attempt to make them stay together would affect other teams? How many other teams banked on them comming apart?

What would you say if the pyramid collapsed? Is it our fault because we should have known it would collapse based on how FIRST designed it?

[dez250]

The way the field interacts with robots has always been part of the challenge of the game. The FRC staff can not and should not be expected to build a field around a single teams robot design.
In 2005 I witnessed multiple Scoring pyramids pull up from the floor because of how many tetras were scored on these, that could have never been predicted (229 at FLR for example). Also in 2007 with the rack, who ever would have thought a team would have been able to move that completely, it just isn't foreseeable.
With the way the field has to be designed to be durable and also transportable, I think the designs this year are very well done, being able to give the most unobstructed goal, and climbing ability to all teams evenly.

[mwmac]

It is week 2 and I saw MC's standing on the "30" inch bar at two regionals today. At a minimum, First should unequivocally end this practice...

[orangemoore]

The MCs are told to stay off the pyramids for the most part but for special times such as eliminations.

[EricH]

Originally Posted by orangemoore

The MCs are told to stay off the pyramids for the most part but for special times such as eliminations.

The MCs should be eligible for G02 fouls. (A Yellow Card for team members climbing onto the pyramid, FWIW.) Second card means that another volunteer MCs for a couple hours. Wait, I'm not sure that's a penalty for the MC... How about a second card means the MC stays inside the netting for a match or two?

[NXTGeek]

The pyramids at SD were noticeably different from each other, with the red pyramid's 10pt bar being too low to the ground. A number of teams were having problems with that and complaining to refs.

[nathannfm]

Originally Posted by mwmac

It is week 2 and I saw MC's standing on the "30" inch bar at two regionals today. At a minimum, First should unequivocally end this practice...

I saw an FTA who shall remain nameless do this to remove a 5 Point Frisbee when it took the field crew more than 5 min to figure out how to do it the right way

The problem I saw most was the sway from side to side at least on the practice one. With all the compounding error the top moved at least a couple of inches side to side when you grab the side bar, it was quite shocking, not something I would want to climb...

And if you have not seen one yet, this is what they look like taken apart.