22-08-2009 00:39

R.C.

Re: pic: Chassis Idea

Personally, I like it. Good Job on the Chassis and I'm loving the Gussets.

Could you please provide specs on the Drivetrain itself. Such as Wheel Specs, Weight, Thickness, etc... Over the course of the 2009 Season, Teams found out to place the radio higher up. You may want to remove it from the CAD or plan to mount it higher up.

22-08-2009 00:51

Rion Atkinson

Re: pic: Chassis Idea

OK. I don;t have any wheel specs.. I just made a wheel like shape for that. This is my first year on a FIRST team so I'm still learning all this stuff. I can tell you a following:

Mass : 39.351 (with all the components.)
The frame in made of 1/8" extruded aluminum.
The gear boxes are AM SS
It will be 6wd by means of a chain. haven't made gears yet. Not sure about the dropped center. I guess it would depend on the game.

Ah ok. Works for me. I'll just remove it for from the CAD for now.

22-08-2009 01:09

MrForbes

Re: pic: Chassis Idea

This is a great time to be learning how to CAD a chassis, and asking for suggestions!

Some comments...

A short/wide chassis can be kind of tippy in games that involve using arms and such. Might want to also work on a long/skinny chassis design, so you can have experience with both when you discover what the 10 game is and figure out what would be best for it.

The main circuit breaker should be near the outside of the robot, so it's easy to access after you put all the other "stuff" on the robot. Also the battery should be easy to change quickly. Having it stand up is often a good idea...

The corner gussets are neat, but if you make the bottom plate out of something that is even slightly strong, they are not needed. Learn about shear strength.

Plan on two motors per side for the drivetrain, it's usually the way to go. Lunacy was a rare exception.

Think about bumper mounting. If you build it into the chassis design concept, then it won't be a difficult issue to deal with during week 5 of build season...if bumpers are indeed required next year.

Also be sure to work on a design that uses legs instead of wheels, you never know what the GDC will think up!

22-08-2009 02:31

sanddrag

Re: pic: Chassis Idea

For your first year (or any year really), this is most impressive. Nice work! You may consider mounting the battery upright to save space. Also, make sure it is constrained securely with some sort of mount/box/members/strap(s).

22-08-2009 09:41

NorviewsVeteran

Re: pic: Chassis Idea

We had bits of loop Velcro on the back of the battery, sitting on hook on the inside of angle iron, and a reallly big ziptie around, tight enough to stay in place, but loose enough that that we could just slide it on/off the battery. We never had any problems with it coming loose and could change in under 10 seconds easy.

Something to consider squeezing in there, and I too like the gussets.

22-08-2009 11:08

Bryan Herbst

Re: pic: Chassis Idea

As an electrical guy, I'm going to give you electrical feedback.

Why do you have two digital sidecars? You appear to only have two victors, and unless you are using every relay in your possession, I think you will find you only need one.

Second have you tried orienting the battery that way, more specifically with the contacts down? The battery has significantly thicker wires than the rest of the electronics, and I am not sure if the wires will agree to that orientation.

Thirdly, as squirrel said, you may want to reconsider the placement of the breaker.

Otherwise it looks like a fantastic set up.

22-08-2009 12:11

Rion Atkinson

Re: pic: Chassis Idea

Thank you very much everyone for your feedback.

I am about to restart this design in order to take in everyone's opinions.

The battery will be changed to upright and it will have its own mount.
It will now have mounts for the bumpers.
The breaker will indeed be moved to a better location.
1 sidecar.


Tanis - I wasn't sure on the sidecars for how many we would need. last year we hooked up enough switches to 1 of then to fill up one side. We most likely wont be doing that many list year. I don't plan on putting in the second sidecar.
No. I haven't and the largest gauge wire I found was 16. The batteries wire is 12. (I was head of the electrical team, but not there for kick off so I didn't know how annoying that cable gets. When we moved the mount we just kept all the 12 gauge wire the same. )

22-08-2009 12:17

DonRotolo

Re: pic: Chassis Idea

Excellent work.

As you reorient the battery and main breaker, consider that these are the wires that you want to keep as short as reasonable, since they carry the greatest current. Also, the battery connector needs to be considered, since teammates will be connecting and disconnecting that battery often.

An alternative to gusset bars are plates, triangular in shape as you ahve the bars, but they are easier to fabricate and mount without welding.

Lastlly, consider how the wheels are driven, since sprockets have a thickness that cannot be ignored. Oh, and think about how to mount bumpers, assuming they'll be a good idea for the 2010 game.

22-08-2009 12:33

Rion Atkinson

Re: pic: Chassis Idea

Where the wheels are at the moment (and were they are staying unless something comes along..) is 2.5" the wheels are 1" wide. So I figure there is plenty of room in there. The center wheel is mounted on the drive shaft of the AM SS. each axle will have a gear. Run a chain around them and all three are powered. I don't really think a chain is more than .5"... Which leaves .5" clearance on each side at least.

22-08-2009 12:37

ATannahill

Re: pic: Chassis Idea

I believe you have some numbers mixed up, for most motors you will want between 10 and 14 gauge wire, the battery wires that are in the kit are 6 gauge but I think 4 is also legal. The 12 you are thinking of is probably the number of volts in the battery

22-08-2009 12:40

Rion Atkinson

Re: pic: Chassis Idea

.. I believe I do too. Serves me right for missing kick off... Thank you very much for correcting me.

Makes ya wonder how the bot didn't blow when I wired it...

22-08-2009 13:32

Andy Baker

Re: pic: Chassis Idea

Looks good... just a couple of suggestions:

- The angle bracing on your frame is excellent for structure, but they take up a bunch of space. One thing you could do instead is to replace the angle tube with an angled sheet brace on the bottom. This way, you could give your battery some more room, moving it away from the PD board.

- Leave room to put in a 2nd motor on the Super Shifters. Sometimes you need 2 per gearbox, sometimes you don't. If you leave room in the layout for 2 motors, you won't need to move things around later.

It takes guts to post your designs. Good for you for making a great design and showing it to us.

Sincerely,
Andy Baker

22-08-2009 23:50

Jeff 801

Re: pic: Chassis Idea

Another thing to remember on the supershifters you don't have any way to shift them shown (pneumatic or servo) which is something to remember because it all takes up space

23-08-2009 13:51

skimoose

Re: pic: Chassis Idea

Another electrical suggestion. Don't mount your gaming adapter down low in the frame especially that close to your high current victors and CIMs. You want the radio higher in the robot and away from sources of interference for optimal data transmission and minimal data loss.

I also agree that unless you have a very complicated robot, you'll likely only need one digital sidecar.

On wire size, the lower the AWG (American Wire Gauge) number, the larger the wire, more current carrying capacity, and lower resistance per foot resulting in lower voltage drop. Therfore, #6 is supplied in the KOP for your main power circuits, but you could use #4 and it would be legal. In cases where #16 is recommended you could use #14, 12, or 10 if you felt that voltage drop would be a significant issue and it would be legal. Just remember, larger wire is more weight, so unless you know you have a voltage drop issue, it's probably unnecessary.

Voltage drop is also directly related to efficiency. Voltage drop and wire resistance is Watts of wasted energy in heat. This can have a serious impact on battery performance when dealing with mechanisms which run at full power for long periods of time during a match. Vacuum venturis, high speed shooters and collector mechanisms are certainly worth watching for energy losses.

Keep thinking up new designs you're on the right track.

24-08-2009 07:52

Al Skierkiewicz

Re: pic: Chassis Idea

OK,
Electrical guy checking in...As Art and Jim have pointed out, you want to increase the size of your wire. Robot rules for many years have specified #6 minimum for all primary wiring. i.e. battery to main breaker to power distribution. Although robot rules allow for #12 for devices fed from 40 amp breakers we use and recommend #10. You can use the battery as counter weight so be ready to move it as needed. The power distro is better suited in the center of the robot. It is in this way that wire runs are minimized and balanced between the two sides of the robot. I can't tell you how many teams have come to me complaining they can't get the robot running straight when they have six feet of wire feeding the motors on one side and six inches of wire feeding the other. Although someone suggested to point the battery contacts down, I don't recommend this. Our high current applications will cause some venting from time to time and you (and the robot inspector) can't see if the terminals are getting into trouble when the battery is mounted that way. Remember that the sidecars do not pass a lot of current so they may be placed almost anywhere. I am suspecting a change in radios so don't dedicate yourself to that size package but do plan on getting it up out of the metallic clutter. In addition to the noise, there is significant reflections of RF down among the metallic parts.

24-08-2009 18:43

Rion Atkinson

Re: pic: Chassis Idea

That you everyone for all the help! Every bit of it has been taken into consideration.

(On the wires.. The largest I can get is 8 gauge... Does anyone know how to make Inventor make 6 or 4 gauge wires?)

25-08-2009 13:24

Jeff 801

Re: pic: Chassis Idea

you have to create your own style for it or you can be lazy and just change the size of the segment.