145 + Glue =awesome?

[colin340]

Originally Posted by lukevanoort

Surprisingly,welding may not be that much stronger than epoxy (if stronger at all). Welding ruins the heat-treatment on the aluminum, which makes its strength take a nosedive. On the other hand, some epoxies are insanely strong and do not affect the heat treatment.

good point but weld can't shatter they can bend

and GrammarNazi your being mean a your Well those teams suck and they should be kicked out this is mean everyone's being nice to you about this we(I) do not mind this we just want you to under stand first better remember- this is more about gp than robots
-colin

[DarkFlame145]

Originally Posted by jgannon

Congratulations on finding a successful fusion of students and engineers that works for your team. It sounds like your team understands the purpose of FIRST far better than teams whose students never touch the robot, or than teams who try to attack this problem with no engineer support at all. Best of luck with the rest of your season.

Thank you very much, that means a lot from someone that is from a team that is in an area with a much larger population then little old Norwich, NY

Originally Posted by lukevanoort

Surprisingly, welding may not be that much stronger than epoxy (if stronger at all). Welding ruins the heat-treatment on the aluminum, which makes its strength take a nosedive. On the other hand, some epoxies are insanely strong and do not affect the heat treatment.

That is very true, when I weld alum. tubing I cause put 2 tubes welded into a "T", let it cool, put it into a vice and rip the alum all around the weld before breaking the weld. It's because the areas around the welds became heat treated and became weaker.

Originally Posted by colin340

good point but weld can't shatter they can bend

-colin

I haven't seen any of my welds on a robot "shatter", but every year i have one cracked or fully broken weld (often my crappy welds). What is nice about epoxy is that it has some stretch to it.

[x7shaddow]

Although some very valid anti-weld points have been brought up, out team has had 3 out of our 5 total robot frames (2008 included) with no trouble from welds cracking, or even the aluminum being weakened from the heat, I think we actualy bent our frame last year from so many hard impacts with both the arena, other robots and various shop components (students included ) and it still has full structural integrity with no strees points showing in metal or welds. I guess one of the main factors would be that they have either been welded with a TIG by students/mentors with more than proficent welding skills or it was sent out to be welded professionally.

[bobdahaxor]

I'm sorry but it seems like the grammer Nazi needs a lesson on gracious professionalism and needs to represent his team better!

[TD78]

wow...interesting idea. i'd have never thought of gluing the chassis together. the past few years we have used 1.5" and 2" bolts that go the top and bottom of the end caps and end rails. much much easier than using all those small bolts that come in the kit. this year and last year we've bought aluminum spacers and faced them down so they fit inside the frame rails (otherwise the rails would bend inwards when tightening down the screws). you can see the bolts and the spacers here: http://www.joemenassa.com/images/rob...s/IMG_8368.jpg.

[Gdeaver]

Metal adheasives CAN be stronger and more cost efffiecint than welding. The mentor that epoxied the frame most likely was trying to expose his team to other joining methods. That is what First Mentors are supposed to do. I try every year to work some composite construction in to our Bot. I posted a picture this week showing another use of epoxy. Hopefully some others saw it and may think of it's use on thier bot.

[M4 Sherman]

I think you still cant beat a bolt and the next best thing is a weld.

Look at the comparison of Liberty ships built by the U.S. during WWII with rivets verse welds.

And the part about the Aluminum failing around the weld is probable because you're using a thin wall tube (Like 1/16").

[David Guzman]

This is pretty cool, it is always nice to see teams try new things. Exploring new ways to do things is what makes robots in FIRST better every year. Congrats to your team on trying new things and sharing them with the CD community.

We used the kit frame back in 2005, at first we kept having issues with bolts getting lose. So we reassembled it and used red loctite on all the bolts and nuts, never had a problem after that.

I am a fan of welding most of our stuff, however not all teams have too many welding capabilities and finding another method will help a lot of other teams get rid of those heavy bolts.

[sanddrag]

Originally Posted by lukevanoort

Surprisingly, welding may not be that much stronger than epoxy (if stronger at all). Welding ruins the heat-treatment on the aluminum, which makes its strength take a nosedive.

According to Metal Forming Magazine, the minimum tensile strength of a weld joint in 6061 aluminum is approximately 24 ksi after welding. The tensile strength of a typical epoxy such as JB weld is approximately 4 ksi. Welding is stronger by a factor of approximately 6 times.

[richalex2010]

What type of epoxy is that, with what additives (if any)?
Looks like a "normal" epoxy (non-JB Weld) with chopped carbon fibre, or something similar.

A few other additives to think about for anyone using epoxies:
Kevlar
Fibreglass
Microballoons (microscopic glass spheres, looks like powder)
Colloidal Silica (rich man's microballoons, IIRC)

One material I've been trying to get my team to look at is a coupld of layers of fibreglass on each side of a sheet of balsa. Some of the strongest stuff I've used, probably on par or a bit weaker than G-10 sheet, and far lighter.

Composites are great, if used properly. A lot of the time they're overkill, though.

[DarkFlame145]

I think it's aircraft epoxy, what it's made out of I have no clue. If it is aircraft epoxy then I have 100% faith that it will hold seeing how the stuff holds things that got 300+ mph in the skies.

[richalex2010]

Yeah, Aeropoxy (and other brands; can't think of them right now) is really awesome. And it actually helps hold together rockets that can break mach three and/or reach FL 300 (30,000 feet) in seconds.

West System and other brands are also really good, and cheaper (not sure about how much cheaper). Polyester isn't so great (pretty much anything you find cheaply), and neither is "hobby" stuff (which is actually more expensive if you need a lot of it; this is anything that you mix with 50:50 proportions).

[johnr]

we to will be trying rivets and epoxy this year after acouple of years of welding frame. something new. also if it works out,in our case,it would get the whole build back into the students hands. hopefully they won't glue them(hands) together.

[jacob07]

Since the Kit frame has been available to use, my team has ALWAYS used red lock-tite on the bolts and nuts to hold our frame together, it is a beautiful thing. It works so well!

[GrammarNazi]

Originally Posted by DarkFlame145

That is the only thing that was not done out of our shop. Some teams have everything fabbed at a shop then all the team does is put it together.

The weak spots on a frame are it's corners, make them stronger then the frame as a whole will be.

The drive train has been tested, our lift fits on it great, and everything is just right. So there shouldn't be a need to take it a part.

So you are saying that the only thing you did was put epoxy in the corners? How is that any better than sending the whole thing to a shop and having everything done somewhere else? A three year old could put epoxy in the corners, seriously...