i dont really understand as to why i see most teams use the KOP metal to make a robot… its not very reliable/strong and u cant make a very strong structural frame (i have seen some KOP bots bend)
now in my exp. i have seen robots break KOP robots to the point of rebuilding.
why not just buy stock and weld?
i noticed some robots who weld never tend to have structural damage and have a really strong frame not held together by bolts and nuts.
so… why are YOU using it? easy to put together? no money? explain…
im just curious, im not trying to make fun of anyone… i just see and ask.
-Cheap
-No fancy machining, which we can’t do, required.
-Faster to put together.
-I have tried and failed to break it.
-easy to adapt to.
We are welding the joints of it instead of bolts this year, but it held up through 2 events last year with no bumpers and bolts with no problem.
In general (there are many exceptions) teams using the Kitbot are somewhat lacking in the resource department, and without welding, precise machining, etc. their robots are more likely to break. Teams with these resources can build stronger robots easier, and also tend to use these resources to make their own chassis to fit their needs better.
I personally love the frame kit. We did some analysis of the frame kit. Our conclusions:
To our surprise, it turns out that the question mark shape has similar (though not identical) structural properties as the same sized box extrusion. That is close enough for us.
Due to the hole pattern, it is actually lighter per unit length to build using the frame kit than using equivalent box extrusion. (IOW, it’s “pre-cheesed” for you!)
The hole pattern and tab on one side are very convenient for mounting accessories. This saves a LOT of time.
It helps us standardize on one bolt type (1/4-20, of various lengths) for almost EVERYTHING.
You’re given parts already precut to roughly the basic drive train frame dimension limits. (FYI, we always cut off 1" per edge, to allow for bolt head thickness to stick out on all sides. Otherwise, it often won’t fit into the FIRST sizing box at a regional! …Duh… However, if you’re welding it, and NO bolts stick out around the perimeter, that may not be a problem for your team.)
If you don’t have aluminum welding available at your school (yes, that’s a totally different discussion), then the frame kit is definitely a godsend to your team.
…and lastly, we’d rather focus our student workforce on the game payload problem, than spend a large chunk of it on the basic framework.
So, overall, it hasn’t been WORTH our time and effort to translate the frame kit into welded frame. As stated, a welded frame of the same box dimension and thickness is always heavier per unit length, AND we’d then have to drill mounting holes all over it anyway. That’s not the best use of our manpower.
(Does that make sense to you?) I hope this helped!
Keith
Chief Engineer, Team 1502 “Technical Difficulties”
but i wouldnt wanna risk my robot breaking just because its somewhat lighter (the team i was with always used a welding frame) and the robot i built broke KOP bots frequently.
now if i knew this would happen (even a slim chance) i would change my gameplan quite quickly.
so why do teams risk it? (i understand if u cant due to not having some resources… but if you DO have them… why arent u using them?)
what is the goal you are trying to get at with this thread, and what team were you on previously?
Why don’t you ask some of these teams who have used the KOP chassis…
121, 148, 229, 2056…
so in the end it has been tested by some of the top teams and have been used by so many others, why waste time and man power and cost? the KOP chassis is something that is in the kit and can be assembled in ONE meeting, the day of kickoff. it’s an excellent frame for teams with a low budget, not many engineers or any of that, and in the end it’s given to you!
As one of one of the rougher “enforcer bots” at the Wisconsin regional last year, I can say that our KOP from shows no signs of being worse for the wear. This is despite running with no bumpers for a few matches and running without the endcaps (clearance was too low to climb ramps) for all of the elim matches.
We through everything I thought the KOP frame would handle at it, plus quite a bit more and I don’t see any signs of budging an inch.
Having said that, the reason we use it is that it is cheap (free) and easy to machine (it already has many holes in it) for a team without complex machining and welding capabilities.
I personally have never seen a kitbot fall apart, and I have seen multiple welds break under situations like those you have described. The kit metal itself is more than strong enough. Loose bolts due to lack of loctite, etc, might cause problems, but I have seen no evidence that there are unavoidable flaws in the basic concept/structure of the kitbot. Until I see this, our team will probably continue using it in some form, and encourage others to do the same.
I have never seen a kitbot frame fail. We have defended and been defended using a kitbot chassis without any noticeable problems. It is pretty light, it does what we need, it is strong enough, and it is easy to work with.
We used the KOP last year and had good results. It survived being run full speed into the opposite wall during every match, our programmers are still puzzled.
Why do people use it?
1)Free
2)easy to use
3)easy to access nuts/bolts for it
4)it is easy to maintain
5)no machining required
6)no welding required
7)not made of unobtainium
Well, I can tell you, that most teams not here on Chief Delphi, and some teams here on Chief Delphi as well have two common reasons why to you the KOP Metal.
Like my team, we have no access to any welding, or huge machinery. Yes, our whole robot is made from hacksaw, hammers, drills, and the usual tools (regular hand tools). Unfortunately, we can not get access to any at the moment. No lathing, CNC machines, nothing. It’s unfortunate but people can work around so, and thus using the KOP to make life much, MUCH easier.
So it isn’t so much about, “Why use it?”, it’s about, “Why do we NEED it?”. Sure we can use Extrusion, but here’s the second part.
Money. Some teams, unfortunately, don’t have sufficient funds to have a custom built chassis. I say, saving money, time, and I admit, the Kit bot is awesome for a provided standard part.
Yet I haven’t seen any kit bot break. Sure it may bend, or warp, but I don’t think the degree of it is large at all in a competition.
May I ask where in the kit bot does it break? If it’s the joints, than its a simple problem of screws and nuts. However, if its the metal itself…
Here’s a good thread from the “debut” of the kitbot. Specifically the post by Paul Copioli about the strength of the kitbot frame. If it is good enough for Paul and JVN it’s good enough for me.
It seems like these observations are skewed by a confirmation bias. Because one thinks that the Kitbot is inherently weak, their attention will automatically be driven towards Kitbot failures and will often overlook contrary evidence (non-Kitbot robots breaking).
I’ve seen just as many non-Kitbot chassis robots bend/break as Kitbot ones.
No matter what choice you go with (KOP or custom), if you don’t build it right it will break.
Our team used the KOP chassis last year, and were fine with it. Which is why we are using it again this year.
We weren’t very aggressive but the few times we were it held up for us fine.
If you put it together properly than it is very strong.
Time is a big reason for us, knowing our team it would be a week and a half to design the chassis and another week to actually build it (exageration of course)
and finally money is a big issue with so much other things that don’t come in the kit we don’t have the money to go buy another frame to be made.
Lack of money, facilities, time or expertise are good reasons.
A few days after Kickoff, one group from our team was drawing out plans for a custom made frame. We would have someone machine it for us. The other half of the team, for lack of anything better to do at the time, decided to put the kit frame together for prototyping until we got our real frame made. Without looking at the instructions (because we didn’t have internet hooked up in the room at the time) we managed to put it together in an hour or so. Then got some old wheels out of the closet and put them on axles through the kitbot frame. We looked at it and thought, “Hmmmm - it might work.” We’ve gone with it, made a couple minor modifications, and it looks like it will work out well for us.
Here are some reasons: Cost. Time. Resources. Strength.
The team I am currently mentoring is a “low-resource” team. No welder. Hand tools only. It’s taken us long enough just to get the thing running…imagine if we made a custom frame. Also, it’s free, and I personally have NEVER seen one break. Not even bend. (I did tell the team to loctite the bolts for the final build. Hopefully they will, so no robot droppings.) Plus, it’s extremely versatile–I can think of three different drivetrains that would just slap in in about 10-15 minutes.
I won’t contradict that evidence, but will agree that with the vast majority of posters on this thread that… properly assembled… the things are darn near indestructible when used in FRC applications. We’ve used them ever since they were part of the KOP… and while we chop them, mill them, weld them and flip them upside down, they always come out far stronger than we need.
I guess you can make anything break if you build it to break (although the kitbot frame is pretty hard to screw up), but anything that breaks a kitbot frame is probably breaking most custom frames of similar weight, too.
