Re: Best frame building material
 

80/20 is only light if you weld it.

When you add in all the connectors, it gets very heavy.

We have used 10/10 since 2003. It was nice since we could just slide stuff around to get it out of the way to access the innards of the robot, or realize that we made a design error and slide a few bolts to correct it. In 2003 we used all the connectors, which added up to be a pretty hefty penny. We didn;t have an issue with weight, but then again, our robot only weighed 90 lbs after we ripped our entirely ineffective stacker off it :D

In 2004, we had a lot of 10/10 left over, and had access to welding equipment, so we welded the 10/10. The frame was extremely light, and still retained most of the modularity you get with 80/20.

Some of the problems with extrusion include the fasteners slipping. This was particularly evident on both robots in that the wheels would continually slip from their intended mounting points. It's easily fixed, but a pain in the $@#$@#$@#. You really have to be sure to check all the time that your connectors are securely fastened. By the time we got to Cal Games in 03', the robot was literally coming apart because everything was so loose.

Before 2003 we had used 1.5" aluminum angle, and in 2002, we used 1.5" steel angle, which left us with a frame that was probably in excess of 40-50 lbs (Way too much strength, even for a game that was nonstop action)

Cory

Re: Best frame building material
 

We have used big aluminum plates separated by spacers since 2001. If you carefully place the plates and don't get carried away with making them too big, this is definitely a lightweight approach. If you are less careful about where you place plates, or if you make them huge for no good reason, it gets heavier.

One nice thing about this approach is that its easy to make multiple parts at once on a mill - once you decide where your holes are, you can make enough for one or two robots in one setup. So it can be a time- and money-saver if you are doing your own milling.

Another nice thing is that the plates serve as great mounting surfaces for things like the drive system - you don't need any extra brackets so this contributes to the weight savings. It is a natural for custom geartrains and multi-motor drives.

Its easy to mill your team number into the side of the bot too! :))

We have used a number of methods to extend structure between the plates: angle aluminum, flanged steel tubing, or other plate structures. My favorite is chrome-moly steel tubing (0.035" wall for "normal" locations, 0.058" wall for those exposed bumpers) with little three bolt flanges welded on the ends. Strong stuff and not too heavy, easy to mount a controller board with just a few tie wraps.

Ken

Re: Best frame building material
 

we used (correct me if i'm wrong) 80/20 1" steel box tubing this year to build our frame. for those of you that were in the practice area behind the pits at SLR, you know just how strong the frame was. our robot ran full speed into a solid concrete post during an autonomous mode practice run and came out unscathed, we did more damage to the post!

and i must admit, making modifications during the build season was a snap, we just used either a hand saw or a plasma cutter to hack off the parts that we didn't need :)

Re: Best frame building material
 

Minor correction, 80/20 is aluminum :)

It can take some big hits as long as you make sure you've got everything braced up well. At first in 2003 we had some doubts as to whether 1"x1" would be strong enough, but it turned out it's plenty strong, and much lighter than 1"x2", which is serious overkill.

Cory

Re: Best frame building material
 

Thats a pretty good idea.. Did you have to sand off the anodization first?

Re: Best frame building material
 

I'm not sure, really. We didn't weld it, some welder at the place where one of our engineers works did it. I'd imagine that they did though.

Cory

Re: Best frame building material
 

That happened to us our first year of using extrusion (2003).. after two regionals our robot was in pretty good shape, but after going through playoffs at Nationals- and keep in mind we took Galileo- our entire frame was warped. The extrusion slipped so much, Daisy 2 is more dented than the average metal canoe. Extrusion was awesome, but the thing that blows my mind is: we had a simple drive system and simple one-motor arm, but we still maxed out at 130 pounds. It's too darn heavy.


We did that this year, and it should've helped except for the extreme weight loss we had to undertake. lost 15 pounds at chesapeake, our frame became so weak and vulnerable before we even set foot on the field. To make things worse we had a faulty control board for our first 5 or so rounds so our robot (dual speed worm gear drive) literally bent its own frame before we could even really compete. Miss Daisy III is crooked now, but what can I say, last year's Miss Daisy only had a T on, and the original Daisy was topless.

Re: Best frame building material
 

There are a number of sources of reinforced nylon connectors that insert into the ends of the tubing and lock it together. :cool:[/quote]

What are some of the sources? Which ones have you found to be the strongest?

Re: Best frame building material
 

1251 (my team) used extruded aluminum becuase it is stronger then that alumnium tubing your team used, however is it much heavier. so a good word of advice if you want to be light don't use extruded use the alumnium tubing. :cool: Extruded is good if your goin for robustness. The decision all depends on your design. Hope that helped.

Drew,
1251 THE TECH TIGERS
TECHNOLOGY FOR THE 21st CENTURY

Re: Best frame building material
 

First, let me answer this. We got square tubes. I believe it comes in a whole array of shapes and sizes. We took the unistrut, machined it down to a size that would nest tightly, but not too tightly, in the FRP. Then, we taped the hole, and screwed it in at a 90 degree angle to the instruct.

This is not frame related in the aspect you are asking about. Team 93, in addition to using the fiber glass (FRP), we also used a large 1/4 in. plate for mounting things, instead of using more pieces of 80/20. We used it to mount gear boxes, our battery, our electronics box, our programming, air compressor, etc. To make this plate strong we had one of our engineers brothers laser cut, then bend out 'ribs', if you will, to make sure it would not flex in any critical part. This part helped the robot meet the weight requirement and still stay robust.

I'm sure myself or Sean Schuff could conjure up some pictures of this plate so you can understand what I'm rambling about.

Re: Best frame building material
 

This year we plan to use the engineering teacher's head, it has got to be the hardest material known to man.

Re: Best frame building material
 

Like Cyberblue, we used extrusion in the past (except for the "pre-me" robots - Rowdy 1 [2000] and Rowdy 2 [2001]). This summer, though, we replaced the frame with a welded box (1 in by 1 in or so) and it worked perfectly. It was 2 lbs lighter and we had weight to put on a pump (essential to the arm). Even though we didn't do great at IRI (because our arm broke in two places during the practice match - took 2 hours to fix, and the whole energy left in a battery issue), the frame was definitely a plus, and welded frames are what separate the men from the boys. :yikes:
An example: Teams 66 and 279, the awesome teams we allied with at nats. Though 279 did use some extrusion in their arm, both 66 and 279 had welded frames (as far as I could see). They had very few limitations, except when the opposing robot would knock it over by entangling with the arm.
There are many more examples of this. Good one: WildStang this year, Beatty 71, and Las Guerrillas (469).

Re: Best frame building material
 

You don't even want me to list all the teams that have had great success with non welded frames.

Re: Best frame building material
 

Umm. No. Fixing a welded frame after a breakage in the non-welded part at a regional where you really have no time for welding is what seperates them.

Welding = Bad.

I would rather take apart extrusion based frames and redo all the screws and fasteners than re-weld a part many times.

Anything that needs special tools and/or skills to maintain especially at a FIRST competition should be kept to a minimum, and welding is one of those special skills.

Re: Best frame building material
 

i don;t know about you all but i bring my mig welder to all the regionals i go to :D ...infact i do