pic: FRC294 Prototype base

[AdamHeard]

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[Madison]

Y'all have obviously given a lot of thought to this, so I'm just curious about what I imagine are some of the most important pieces of information for all FIRST teams -- how much does it weigh and how long will it take to manufacture and assemble?

[AdamHeard]

Originally Posted by M. Krass

Y'all have obviously given a lot of thought to this, so I'm just curious about what I imagine are some of the most important pieces of information for all FIRST teams -- how much does it weigh and how long will it take to manufacture and assemble?

I actually don't have an exact weight because I've been so busy between work and just CADing it... I didn't have the best practices so 1/2 the stuff is missing material properties. We made almost every practical effort to lighten it though; Each rail (inner and outer) is 3 +/- .05 lbs (keeps changing slightly with adding stuff), the wheels are .4.

for comparison, Last year's with a heavier frame came it at 50 lbs or so. I'll get a precise weight soon.

As for production,
-We have a jig setup to CNC the rails. They take about 2 hours to cut each (what I've heard, I didn't see them cut); During that time, we'll have kids on manual mills and lathes cutting the small parts out (most are really easy to make) and will probably finish within the day.
-The Wheels, Gearbox plates & shafts and the Frame will be cut/welded by our sponsor (NG), with a lead time of 2-3 days.
-All efforts were made to ease manufacturing time; off the shelf spacers, the wheels match the AM sprocket hole pattern so we just bolt them on, etc...
-We could spend two solid days in the machine shop and finish it; However, We'll probably wait until week 1.5-2 to make sure there aren't any drastic changes we want to make.
-Not counting of electronics, We could have one group assemble the modules, and another do the gearboxes and mate them at the end of the day.

Also, almost forgot this... View the .dwf in 3d here.

We hope to compete with it at the SCRRF Fall Classic on 9/29.

Any more comment/critisism is appreciated.

[chris31]

Unfortunately the DWF viewer link you posted does not work. Could you post it again please. Thanks.

[Cory]

Originally Posted by AdamHeard

-We have a jig setup to CNC the rails. They take about 2 hours to cut each (what I've heard, I didn't see them cut);

It takes two hours for each rail on a CNC? that seems like an awful long time.

Your design looks good though. The modularity of it is great. Reasonably simple as well.

[AdamHeard]

Originally Posted by Cory

It takes two hours for each rail on a CNC? that seems like an awful long time.

Your design looks good though. The modularity of it is great. Reasonably simple as well.

Awwe... I forgot that those were last years rails. Last year the jig cut both an inner and outer plate, the gearbox plate, the tensioner, the blocks the center wheel rode in, and two different style tensioners all at once.

Since we haven't cut the new ones yet, I'd say no more than an hour each.

[Gabe]

Why aren't the fronts sloped anymore? That was the eyecatcher form your frame last year that made me remember your robot from everyone else's.

[AdamHeard]

Originally Posted by Gabe

Why aren't the fronts sloped anymore? That was the eyecatcher form your frame last year that made me remember your robot from everyone else's.

I have the sketches to do it, but we end up with a heavier frame. I'm hoping they won't be necessary next year, but if needed they can be added back in.

[Peter Matteson]

I would suggest leaving yourself a lot of leeway for increasing the ride height and attachment points for joining the 2 sides. That way when you see the layout of the field next year you can tweak you design with minimal impact to allow for the climbong of ramps, stair, logs, teammates or whatever is thrown at us in the game design.

Also the cross-members from pod to pod should have a mid span reinforcement of some kind. As soon as contact is made a few times even with bumpers you may find you no longer fit in the box.

Pete

[M. Mellott]

Very nice design--obviously well thought-out to cover so many design options!

[T3_1565]

Thats a really nice design you got there with a pretty beastly transmission system!! nice and low clearance too. I like to see that! *grins*

[Alan Ing]

Have you used Team 33's design before?

In 2005 we used a modified Team 33 style 4 speed transmission. Aluminum side plates instead of Delrin and oilite bearings for the sliding members. We also used 2 CIM motors per transmission through some custom gearing and added additional reduction for a top speed of around 12 - 13 FPS in high. The transmission shifted perfectly every time and it was really neat to hear it constantly shift. It served us very well that year but we did have a problem with it. The shifting gears were prone to heavy wear on our machine. All of the hard shifting caused the teeth of the gears to elongate and become pointed as well as show extra signs of wear where the gears jam into each other during each shift. At Las Vegas, I showed a set to Andy Baker, and he mentioned that everything looked like it was constructed right (proper welds and all, but that he had not seen this problem before). We ran through 5 sets of cluster gears before the season ended (2 regionals and championships).

Now I can't say that this will happen to your team since we did modify the design, but we finally resorted to case hardening all the gears with Kasenit and a small furnace before we got acceptable wear resistance.

Should you also have this problem, consider case hardening the gears. We still use the robot for demos and the gears look fine.

As a suggestion, if you automate the gearbox, consider locking out 2nd gear. With 4 CIMS, the robot stays in 2nd for only a fraction of a second and almost immediately shifts into 3rd. We played with all sorts of rpm shift points, but eventually we just locked out 2nd making it a 3 speed and the robot worked much more smoothly. Of course we could manually put it into 2nd if we wanted to.

The Team 33 design served us very well in 2005 and is about the coolest to hear operate. Were glad we made it, but frankly we don't use that design anymore since it is much easier to buy AndyMarks solution and modify them for our use.

Anyway, I thought I'd share our experiece with the 4 speed design in case you haven't tried it before.

[Herodotus]

Originally Posted by M. Krass

Y'all have obviously given a lot of thought to this, so I'm just curious about what I imagine are some of the most important pieces of information for all FIRST teams -- how much does it weigh and how long will it take to manufacture and assemble?

We've gotta get a program that automatically asks these questions whenever a piece or CAD design is posted.

I'm really liking the design. What is best is the flexibility in design you have left by allowing the wheels and gearboxes to be swapped out. That means you could theoretically use this design from game to game while only changing the parts you need to. The fact you can change it to a Mecanum drive fairly easily alone is quite awesome.

Overall a sleek design.