Welded Frame Horror Stories

[Tristan Lall]

Originally Posted by Andrew Blair

We have the capability to build a second frame, and our design makes it extremely easy (comparably to most other drive setups) to swap an entire drive train, but I am still somewhat worried about a frame taking the kind of beating our team would give it.

Just remember the spare part weight limit.... 20 pounds of custom-fabricated items may not be sufficient for a frame.

[Billfred]

Originally Posted by Tristan Lall

Just remember the spare part weight limit.... 20 pounds of custom-fabricated items may not be sufficient for a frame.

...but there is always sticking the spare in the crate, at which point you're only limited by how much you can fit in the crate. (Then again, knowing what they charge for crate overages, I'd almost rather deal with the broken weld. )

[Tristan Lall]

Originally Posted by Billfred

...but there is always sticking the spare in the crate, at which point you're only limited by how much you can fit in the crate. (Then again, knowing what they charge for crate overages, I'd almost rather deal with the broken weld. )

That certainly works too, if you can disassemble the frame, or wedge it in somewhere. Or you can ship a second crate for spares*.

(Also, I'm now recalling that the rule was 25 pounds, not 20....)

*The 2006 rules say that you may enter one robot per team. But if the spare (meaning identical, for all intents and purposes) robot is a spare fabricated assembly, and is packed in "the crate" (presumably meaning "one of the crates", since teams are allowed to ship 2), are you really entering twice? I think not, since the robots cannot compete simultaneously. So you could do even better than just a spare frame, if you really wanted to annoy everyone.

[ChrisH]

Originally Posted by Tristan Lall

That certainly works too, if you can disassemble the frame, or wedge it in somewhere. Or you can ship a second crate for spares*.

(Also, I'm now recalling that the rule was 25 pounds, not 20....)

*The 2006 rules say that you may enter one robot per team. But if the spare (meaning identical, for all intents and purposes) robot is a spare fabricated assembly, and is packed in "the crate" (presumably meaning "one of the crates", since teams are allowed to ship 2), are you really entering twice? I think not, since the robots cannot compete simultaneously. So you could do even better than just a spare frame, if you really wanted to annoy everyone.

Hmmm I think I hear phones ringing. Panic calls to the Rules committee to figure out how to close THAT loophole, which you could drive a truck through. Have you considered a career in Law Mr Lall?

[Ben Piecuch]

Originally Posted by Tristan Lall

*The 2006 rules say that you may enter one robot per team. But if the spare (meaning identical, for all intents and purposes) robot is a spare fabricated assembly, and is packed in "the crate" (presumably meaning "one of the crates", since teams are allowed to ship 2), are you really entering twice? I think not, since the robots cannot compete simultaneously. So you could do even better than just a spare frame, if you really wanted to annoy everyone.

So, you can't compete at the SAME event, but could you compete at a DIFFERENT event with the 2nd robot? I guess that would effectively be two seperate teams, with two separate robots, with two separate budgets, under just one school...

(Sorry, I'm not trying to hijack this thread... should we split it off into something different?)

BEN

[Tristan Lall]

Originally Posted by Ben Piecuch

So, you can't compete at the SAME event, but could you compete at a DIFFERENT event with the 2nd robot? I guess that would effectively be two seperate teams, with two separate robots, with two separate budgets, under just one school...

(Sorry, I'm not trying to hijack this thread... should we split it off into something different?)

BEN

Two teams at one school is allowed (two entry fees are paid, two numbers are assigned, etc.). Your school could compete at two simultaneous events, but since there's only one robot per team, your team could not. According to the rules, any custom-fabricated robot part can have fabricated spares that aren't part of the robot until installed, as long as they're identical to what's on the "real" robot. And if you ship spares in the crate, there's no weight limit.

[Aren_Hill]

as far as the square tube frames go has anybody used 1x1x1/16" tube since with bumpers dent resistance wouldn't be an issue. i just know it would be interesting to weld but it would be alot lighter. i'm planning on using a tube frame for a prototype drivetrain and would like some opinions on 1/8" or 1/16"
i think wildstang used 1/16" this year not positive though.

i was also thinking hybrid such as 1/8 for the outer rail and 1/16 for all smaller assemblies and small braces just to keep it light and strong

[Madison]

Originally Posted by Gear

as far as the square tube frames go has anybody used 1x1x1/16" tube since with bumpers dent resistance wouldn't be an issue. i just know it would be interesting to weld but it would be alot lighter. i'm planning on using a tube frame for a prototype drivetrain and would like some opinions on 1/8" or 1/16"
i think wildstang used 1/16" this year not positive though.

i was also thinking hybrid such as 1/8 for the outer rail and 1/16 for all smaller assemblies and small braces just to keep it light and strong

The practice chassis we built last Fall was made from 1x1x.0625 and welded and we have had no trouble with it at all. The competition chassis was bolted together rather than welded since we outsource our welding, so I can't say with any authority how it would've withstood the rigors of an event.

Though most of the work I do uses bolts, I always use 1/16" wall tubing when I can.

[Cory]

Originally Posted by Gear

i was also thinking hybrid such as 1/8 for the outer rail and 1/16 for all smaller assemblies and small braces just to keep it light and strong

We do this in low stress areas of our robot.

[sanddrag]

To prevent your frame from warping during welding (and to make it stronger), I recommend a design with pieces that fit inside each other, like the first pic on my earlier post. That 1x1 tube in the lower front and rear goes clear through the 1.5x2" side rails. That frame came out flatter than flat.

[dubious elise]

Heheheh...

Since team 269 began using welded steel frames in 2004, we have not had many problems at all (save rusting - but we learned quickly from that one!). That is, of course, until this year. Within days of shipping our robot in 2006, our frame was a gigantic box - taking up as much of the allowed dimensions as possible. After a pre-ship scrimmage, we realized that we wanted to make some rather drastic modifications that involved cutting off two of the corners of the box to form a sloped front to the 'bot. Of course, after doing so, you simply cannot leave stray ends of square steel tubing because that is, frankly, not structurally sound. Nor is it safe. So alternate pieces of steel were masterfully gas-welded on by one of our mentors to finish the slanted portion (we already had our electronics firmly in place and did not have time to completely un/re-wire our robot).

Everything was honky-dory until the Championships rolled around. I was messing with the netting and noticed a fissure in one of the gas welds. After pointing it out to some of the other kids on the pit crew, we checked all of the gas welds and found another one that was snapped clean through. Luckily, we were just barely enough under weight to allow for repairs involving a very long, threaded rod and some pieces of sheet metal that were used to stabilize the junctions of steel in necessary areas.

The moral of the story is probably to do things 'right' the first time. The counterpoint is that change happens. Rather than being a horrible loss, this was a great learning experience.

[EHaskins]

This year 1103 used a welded drive. The only problems we had were because of some afterthought parts that were add using rivets. I'm not really a builder, but I think we used 20-22 gauge aluminum.

NOTE: I'm not considering the turret/tower assembly part of the frame. Because we believed the turret didn't need to be welded if it was attached to the corners corners of the drive.

[Tristan Lall]

Originally Posted by dubious elise

So alternate pieces of steel were masterfully gas-welded on by one of our mentors to finish the slanted portion (we already had our electronics firmly in place and did not have time to completely un/re-wire our robot).

This is an important point: don't use an electric arc welder on a robot with its electronics attached. That can easily become an expensive mistake. If you must weld, use a torch like they did. (And welding with a torch doesn't really work on aluminum. It oxidizes too fast without shield gas.)

[Aren_Hill]

thanks for the input on my 1/16 questions i'm now planning on creating a hybrid frame with an outer 1x1x1/8 rail and 1x1x1/16 innards to keep it light from some of the scant frames i've seen on here i think it should be pretty robust

[Stephen Kowski]

Originally Posted by Gear

i was also thinking hybrid such as 1/8 for the outer rail and 1/16 for all smaller assemblies and small braces just to keep it light and strong

we did this on our base in 2005....worked incredibly well....i would recommend to any team with a professional welder, otherwise 1/16th is very difficult to weld....