Team 95 2017 Build Thread

[Tuba4]

Originally Posted by JamesCH95

However, this game is quite well-designed. Focusing on GEARs and climbing will only enable winning if you are tremendously better than the opposing alliance because of the discrete, and increasingly difficult, gear scoring tiers. For example: an alliance that can deliver 11 GEARs cannot out-score an alliance that can only deliver 6 GEARs, all else being equal. So we concluded that we should have some capacity to score FUEL. Also, a stunning conclusion.

I totally agree with your premise that gears and climbing will rule. But you have miscalculated slightly. It only takes 9 delivered gears to start all 4 rotors. You did not take into account that there is one reserve gear and three prepopulated gears. However gear 6, 7 and 8 by themselves earn you no points. It takes gear 9 to make it work!

***Edit*** My thought is inaccurate. It does indeed take 12 gears.

[Ginger Power]

Originally Posted by Tuba4

I totally agree with your premise that gears and climbing will rule. But you have miscalculated slightly. It only takes 9 delivered gears to start all 4 rotors. You did not take into account that there is one reserve gear and three prepopulated gears. However gear 6, 7 and 8 by themselves earn you no points. It takes gear 9 to make it work!

Answered here.

Love looking through this thread every year! It's very interesting to see how other teams break down the game and strategically design their robots. Thanks for doing this!

[Tuba4]

Originally Posted by Ginger Power

Answered here.

Love looking through this thread every year! It's very interesting to see how other teams break down the game and strategically design their robots. Thanks for doing this!

You are indeed correct 12 gears it is! My apologies!!

[JamesCH95]

Originally Posted by gorrilla

What was the purpose of the pop outs on this 2014 robot?
Just to catch the trackball?

Yes, more or less. We could human-load from almost anywhere in the near-field because we were such a large target. In a few matches, were our alliance partners were bold enough, we caught over the bar quite effectively.

Originally Posted by Fields

I am curious about your brake system and effectiveness.

Are you just using 4 rubber stoppers and do you have any video of someone trying to push you in competition?

4x traction pads. No video that I know of, but in 2014 it worked well for us.

When the sides opened up it was basically hanging a giant 'kick me' sign on the robot, the brakes kept us from getting pushed out of position when receiving the ball or catching a launch.

[Kevin Leonard]

I love this thread every year. Awesome job, 95, the CAD looks great!

[NShep98]

Originally Posted by JamesCH95

4x traction pads. No video that I know of, but in 2014 it worked well for us.

Could you elaborate on what you mean by "traction pads"? We're trying to experiment with different materials on carpet.

[JamesCH95]

Originally Posted by NShep98

Could you elaborate on what you mean by "traction pads"? We're trying to experiment with different materials on carpet.

3M makes a line of polymer grip tape that can be quite effective. Conveyor belting has been used in FRC traction wheels for years now. McMaster has a wide range of rubber sheets that interact favorably with the carpet. We settled on a conveyor belting in 2014, but our knowledge of grip-material has increased since then and I don't know what we'll wind up using this year.

Brakes are a potentially tricky business because you'll have to prove to the inspector that it won't cause carpet damage. Make sure to keep any metallic components well-clear of the carpet and eliminate any features that could snag.

[pmattin5459]

Originally Posted by JamesCH95

3M makes a line of polymer grip tape that can be quite effective. Conveyor belting has been used in FRC traction wheels for years now. McMaster has a wide range of rubber sheets that interact favorably with the carpet. We settled on a conveyor belting in 2014, but our knowledge of grip-material has increased since then and I don't know what we'll wind up using this year.

Brakes are a potentially tricky business because you'll have to prove to the inspector that it won't cause carpet damage. Make sure to keep any metallic components well-clear of the carpet and eliminate any features that could snag.

The rubber pads don't cause damage while dragging on the carpet?

[JamesCH95]

Originally Posted by pmattin5459

The rubber pads don't cause damage while dragging on the carpet?

No worse than when a robot gets pushed sideways.

[JamesCH95]

Fabrication has started with drive pod plates. We use HSM Works to CAM directly in Solidworks. We blank the plates and non-critical features with a CNC plasma cutter and finish machining with a prototrak knee mill. The Tormach Tooling System has been a great addition for this year, making tool changes much easier on this type of mill.



Here you can see blanked vs machined plates.



This is our general fabrication style, it has worked well for us for several years now.

[Mary Jane]

Sick robot bro

[JamesCH95]

Assembly of the practice robot begins!

[JamesCH95]

A little CAD adventure for tonight.

I have started modeling our hopper. Maximizing the volume available to us, while considering a number of other constraints, was somewhat challenging. However, there is a straight-forward way to model usable hopper geometry without a ton of effort.

First, insert a block that covers 2 dimensions of the volume you can occupy. Don't worry about the 3rd dimension just yet.



Use extrude cuts judiciously to provide clearance around components in that 3rd dimension.



Next, I opened the part on it's own now that I've established the maximum volume it can occupy. I added some slopes to the bottom surface to push FUEL towards the shooter.



We still have a solid body, which is not great to store things in. Shell to the rescue! Shell is one of the more underrated tools for sheet metal design in SolidWorks in my opinion.



This gives a good body that we can convert to a sheet metal part. SolidWorks' sheet metal conversion utility is very good at picking out rip edges as you specify bend edges.

[JamesCH95]

Continued (darn 5-image limit...)

Better make sure your 2D pattern doesn't overlap itself. Took me 3 tries to get this one to a happy place.



Fold it back up, apply your material/visual effects, and ta-da! Most of the geometry is there!



To finish things up I've added some fillets to keep sharp corners away and punched in a number of mounting holes to keep the hopper in place. I also massaged the geometry a little more to get a few features in and to avoid some things I view as potential problems.

[Sam Skoglund]

Should it concern me that your rookie year says 2001 and yet you claim to be the one doing the CAD modeling? I though high school students were supposed to do the design work?

Regardless, awesome job! I enjoy this thread each year!