Cool Frame Ideas?

[geeknerd99]

Aluminium outer frame, lugged to carbon fiber superstructure. Light, strong, blingiful black and polished silver. Because on 401, we're addicted to mirror polishing aluminum.

[Dan Petrovic]

We're working on a frame that goes together easily and* comes apart easily. It will require a lot more machining, but we think it will totally be worth it.

* You can sometimes have one, but not the other.

[dtengineering]

If you weld the KOP frame together and pull out the bolts, you would be amazed how much weight you save. All those little bits of steel add up! Not only that, but the frame comes out stiffer, and you never have to worry about a bolt coming loose.

If you have someone who can TIG weld, or even have access to a MIG with a spool gun and appropriate wire and gas for aluminum, frames become much less daunting, and a lot of things that seem like problems suddenly disappear. 3/4" thin walled square tubing makes great superstructures!

If you can't TIG or MIG in-house, then keep in mind that somewhere in your community there is someone who wants to weld your robot for you. People who like welding tend to like welding cool things, and competitive robots are generally regarded as a pretty cool thing. Perhaps a local community college or trade school can help you out.

Of course there are many other examples of cool frame ideas... pultruded fibreglass comes highly recommended in some posts. But don't try welding it.

Jason

P.S. It just ocurred to me today that if you covered your robot in competition carpet that from certain angles you would appear to have a very "stealthy" machine. From other angles, of course, it would just be ugly.

[EricH]

Originally Posted by dtengineering

3/4" thin walled square tubing makes great superstructures!

I agree! See team 330's 2006 robot (shooter frame) and 2007 robot (ramp frame). You can't put a lot of holes in, though; it has to be welded.

[quote=dtengineering;650586]If you can't TIG or MIG in-house, then keep in mind that somewhere in your community there is someone who wants to weld your robot for you. People who like welding tend to like welding cool things, and competitive robots are generally regarded as a pretty cool thing. Perhaps a local community college or trade school can help you out./quote] Some machinists are also like that... In the case of some SoCal teams, one such is also an instructor at the local community college. Shop use and he could make parts for teams--not a bad deal.

[Molten]

Originally Posted by dtengineering

3/4" thin walled square tubing makes great superstructures!

I disagree. We use the 1 1/2" Aluminum tubing and it makes it much stronger. Last year, our robot got tipped over 3 times and did not show the slightest hint of damage. When making a frame, keep in mind that the best robot is lousy once it falls apart. The main point of the frame is to keep everything from falling apart. It does not necessarily have to be fancy, it just has to be functional. Remember, function over form.

[dtengineering]

Originally Posted by Molten

I disagree. We use the 1 1/2" Aluminum tubing and it makes it much stronger. Last year, our robot got tipped over 3 times and did not show the slightest hint of damage. When making a frame, keep in mind that the best robot is lousy once it falls apart. The main point of the frame is to keep everything from falling apart. It does not necessarily have to be fancy, it just has to be functional. Remember, function over form.

Obviously 1 1/2" tubing is stronger than 3/4" tubing. It is also heavier and takes up more space. We have had no damage to our welded 3/4" thin-wall tubing superstructures for the past two years (despite "vigorous" interaction with other machines), but we do design our superstructures for using the finer tubing, with some good gusseting at the corners.

There is nothing wrong with making your robot stronger and stiffer, for as you say a broken robot is no fun. Teams need to make a trade off between strength and weight that only they can decide. We have found success building very durable, lightweight superstructures (which we weld to the KOP frame) with 3/4" square thin-wall Al tubing.

Jason

[Molten]

Originally Posted by dtengineering

We do design our superstructures for using the finer tubing, with some good gusseting at the corners.

Maybe with gusseting, it would be fine. And I will admit some of the older teams make some great bases with the 3/4" tubing. However, to all of the new teams out there, you probably do not want to try this on your first bot. It works but you need to be well versed with stress analysis. Also, I suggest you have plenty of welders as I believe that you will have many more joints to cover. If, after reading this, you new teams are still confident on using this for your frame, Good Luck.

[EricH]

Originally Posted by Molten

I disagree. We use the 1 1/2" Aluminum tubing and it makes it much stronger. Last year, our robot got tipped over 3 times and did not show the slightest hint of damage. When making a frame, keep in mind that the best robot is lousy once it falls apart. The main point of the frame is to keep everything from falling apart. It does not necessarily have to be fancy, it just has to be functional. Remember, function over form.

I didn't say a thing about using it in the drivebase. Superstructure is the part of the robot above the drviebase. On our robot, we use 1 1/2" x 1" x 3/4" tubing for the drive frame and key superstructre (masts for arms, for example). 3/4" thinwall is used for stuff where we either need it to weigh nothing or we don't really care. It is pretty strong though. 330 used it for ramp framing last year. It supported about 140 lbs, often charging onto it, and we were more worried about the corrugated plastic being gouged than we were about the frame. I just wouldn't recommend using it for a drivebase.

[M. Mellott]

Here's a product I found...I haven't invested any funds to buy pieces for testing, but it looks great for making quick prototype frames:

http://www.eztube.com/

[Qbranch]

Originally Posted by M. Mellott

Here's a product I found...I haven't invested any funds to buy pieces for testing, but it looks great for making quick prototype frames: http://www.eztube.com/

Watch out!

We tried this stuff and it does look fantastic on paper, but they have a huge issue with being out of square. Well, not the connectors themselves, but what you put together with them. When we tapped our connectors in everything was nice and strong... but horribly out of square.

The robot frame we put together couldn't even hold an axle straight, let alone sit level. Maybe if you used force gauges or something when pressing the connectors in, or had really close tolerancs on the ID of the tube you use it would work... but just a heads up, with your ajax square tube it doesn't look too pretty...

-q

[wilmo]

Watch out!

We tried this stuff and it does look fantastic on paper, but they have a huge issue with being out of square. Well, not the connectors themselves, but what you put together with them. When we tapped our connectors in everything was nice and strong... but horribly out of square.

The robot frame we put together couldn't even hold an axle straight, let alone sit level. Maybe if you used force gauges or something when pressing the connectors in, or had really close tolerancs on the ID of the tube you use it would work... but just a heads up, with your ajax square tube it doesn't look too pretty...

The EZ Tube was exactally what I was looking for someone to say. Did you use your own extrusions or the Eztube extrusions made for the connetors, did you use the composite or the steel core?

[JamesBrown]

Last year with 1493 we built a custom frame, the sides contained the transmission (a custom 2 speed based off the AndyMark shifter) and the wheels, the two sides were connected by 1 inch square tubing with 1 inch solid aluminum cubes welded on the ends. We threaded the cubes and connected the sides with counter sunk bolts. this allowed us to quickly remove one entire drive module and replace it with a spare. Allowing us to make repairs without having to miss matches of work directly around the robot.

I am going to attach a picture of the chassis, if you have any questions feel free to ask.

[AdamHeard]

Originally Posted by JamesBrown

Last year with 1493 we built a custom frame, the sides contained the transmission (a custom 2 speed based off the AndyMark shifter) and the wheels, the two sides were connected by 1 inch square tubing with 1 inch solid aluminum cubes welded on the ends. We threaded the cubes and connected the sides with counter sunk bolts. this allowed us to quickly remove one entire drive module and replace it with a spare. Allowing us to make repairs without having to miss matches of work directly around the robot.

I am going to attach a picture of the chassis, if you have any questions feel free to ask.

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

[JamesBrown]

Originally Posted by AdamHeard

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

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.

[M. Mellott]

Originally Posted by Qbranch

Watch out!

We tried this stuff and it does look fantastic on paper, but they have a huge issue with being out of square. Well, not the connectors themselves, but what you put together with them. When we tapped our connectors in everything was nice and strong... but horribly out of square.

The robot frame we put together couldn't even hold an axle straight, let alone sit level. Maybe if you used force gauges or something when pressing the connectors in, or had really close tolerancs on the ID of the tube you use it would work... but just a heads up, with your ajax square tube it doesn't look too pretty...
-q

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.