Re: Cool Frame Ideas?
 

Just curious.... Why were the center wheels located more towards the centerline of the robot than the outer wheels?

Re: Cool Frame Ideas?
 

Thank you for the info--I too was hoping that by mentioning EZ Tube, somebody had to have seen it and tried it. Yes, I would imagine that in order to get a box frame that was square, you would have to have the opposite tubing pieces cut with 90 degree squared ends and be very accurate on the lengths since the lengths are controlled by the connectors bottoming out against the ends of the tubing. Keeping it squared up could probably be helped with some thin aluminum gusset strips and rivets, but now it's not so EZ.

Now that I've had time to look, the 80/20 system and the EZ Tube system look very similar, at least in concept, even with the availability of extruded tubing with panel-mounting flanges. EZ Tube connectors seem longer and have the option of the steel-core reinforcement (probably adds too much weight for a robot frame...probably).

Of course, if you're not worried about reusing the connectors, you could always use standard thin-wall 1" tubing and some two-part epoxy like JB Weld.

Re: Cool Frame Ideas?
 

We may try some more composite work this year. Last year we learned how to do some basic layups and such, but it would be really cool to build an arm or more interesting mechanism out of carbon fiber rather than a square ramp, which rarely got used. Unlike what someone said, you don't need a large oven, you can build a simple one with just heat lamps. You just need to get the temp up to around 100 or so. Last year we turned a tool closet into a "hot box" to cure our ramps.

Re: Cool Frame Ideas?
 

In past three years, our team has welded together an aluminum frame (hot metal, flying sparks, random passerby blinded over the shield at 8:30pm, what's not to love?:D). Last year, we had it professionally done when we realized something was wrong with our MIG, and our team spent more time fixing it than actually welding. Usually the students weld... This type of frame is sturdy, bottom-heavy and we can always include our traditional 10-degree wedge, but can cause difficulties in adjusting or repairing the drive train. This year, we're going to try to design a frame that is just as sturdy but doesn't require extreme flexibility in the hands or a robot tipping to fix the drive train.

Re: Cool Frame Ideas?
 

I don't know about these ovens you speak of.

Team 100 has used carbon fiber many times in the past. Usually we've just connected the pieces with resin and fiberglass.

-1995 We built our drivetrain out of a single piece of laminated carbon fiber with holes cut for wheels.

-2005 Our entire arm was made from honeycomb laminated carbon fiber that was resined together at the joints.

-2006 Our electronics board was made from honeycomb carbon fiber.

-2007 The v.2 "Head" (our manipulator) was made from a combination of wood and fiberglass with reinforced carbon fiber edges.

I'm personally not a big fan of the stuff. It takes special drill bits and saws to cut. And the edges are razor sharp, and can easily cut through wires and flesh :ahh:!

But if you're still interested in using it check out your local Tap Plastics, or The Robot Market Place. I know in the past it has always been donated to us by Battlebots builders.

I tried to get a local bike shop to sponsor us last year and build our frame out of carbon fiber (using the same techniques they use to make custom bikes). But they were neither enthusiastic nor happy about spending thousands of dollars on us :D So it fell through...

Re: Cool Frame Ideas?
 

I was referring to what Qbranch mentioned...

While in industry, autoclaves and ovens are often used, you can still get a good cure from building your own hot box.

That's the kinda thing that would be interesting to make. Do you have any pictures?

Re: Cool Frame Ideas?
 

Our team has just started to weld the KOP frame just last year. We were amazed at how much weight was saved when not using the steel bolts. Additionally, the frame was stiffer and we never had to sweep magnets across the floor to pick up the dropped hardware. (In previous years, we would lose at least 4 to 5 bolts each time we drove the robot. That was before we started using nylock nuts.) So for something that is cheap, quick and strong, just welding the aluminum frame if a great option. Also, you might want to considers using the U rails which have the extended bar (the one used for mounting the wheels) sideways and cutting off the excess aluminum which isn't giving any structural support. Here is a crude example of this.


Rotate this
*__
l__
**l
**l

To look like this

_ _
l **l___

(The asteriks are just there to space the lines out. My formatting is stripped each time I've tried to submit it.)

This has saved us a lot of weight over the past year.

We have considered using carbon fiber or fiber glass, but the big drawback to us is that repairing broken components is difficult. These materials can't just be welded or braced with another bar, we'd need to bring replacement parts and swap out the broken for the working. We've also found that pound for pound fiberglass is about as strong as aluminum, so we have never found a reason to switch.

Re: Cool Frame Ideas?
 

2004 and 2005 we built our robot out of HDPE. We found a local company that could weld the plastic. pictures http://team1322.org/pictures.htm

Re: Cool Frame Ideas?
 

Wow, thats a cool idea! Did you have much of an improvement in weight reduction? Any problems with warping? Unexpected benefits? Detriments? Why did you stop using HDPE in your machines?

I remember making our 2006 robot's auto-retracking guides (in case the robot tried to throw a track) out of UHMW and had a heck of a time doing it... i think i spent more time whittling with an exacto knife than actually machining the parts.

Very interesting...

-q

Re: Cool Frame Ideas?
 

No savings in weight, but this was before bumpers, was very srong but did flex, I think thats what made it strong. The big benifits was that the students could work on the material with out hurting themselves. It was like working with wood with out the splinters. When you run a wood screw into it it held very well. The weld are just as strong as the material. We have not useded it because of the design of the robots would not make it feasable.

Re: Cool Frame Ideas?
 

If I Recall it was just an ease of mounting decision. We wanted wide wheels in the center to push but didn't want to have to make the whole drive module wider.

Re: Cool Frame Ideas?
 

Ah, thanks. I was pretty well assuming we'd need to drill through the connector and bolt it since I don't trust anything that's meant to be a press fit, so maybe that would be enough to hold even a loose nylon connector in place. I'll order a handful and see how it goes, I guess, but I can't see going through the time or expense of ordering new metal stock; especially if it's already anodized and harder to work. Even with a bolt through each, it seems like this will be as light or lighter than our existing methods of joining tubes -- lots of rivets and joining plates. The really nice thing about these is that they'll save lots and lots of manufacturing time, we hope.

Re: Cool Frame Ideas?
 

Search before you post :p I got this picture off of your own team's website!

Re: Cool Frame Ideas?
 

side panels:
1" thick lightweight aluminum honeycomb, laminated to high density carbon fiber composite sheets on either side of the honeycomb.

internal frame: some 1x1x1/16" box beams to keep the side panels from crushing inwards.

analysis on such honeycomb and carbon fiber side panels show that the central layers of honeycomb take next to no force, and all the force is taken by the outside edge. so make it out of carbon fiber. superlightweight, and its strength increases exponentially the thicker the honeycomb layer is. then just make up a simple frame to keep the side panels in place, and cover the carbon fiber with like 1/2" foam to keep it from cracking under high pressure impacts. and then you have a really strong, lightweight frame.

my research group is using stuff like this... its lots of fun. the stuff weighs as much as foam and is as rigid as a steel plate.