Team 95 2017 Build Thread
 

Starting early this year!

After the game reveal we considered what would be the most effective way to score points. Crude analysis below.



We then brainstormed some ideas on how to play the game. I will not attempt to justify any of their names, and ran them through a weighted decision matrix to help us pick a design.



Using these analyses we concluded that scoring GEARs and climbing would be the best way to generate points and thus deserve a high priority in our design and build efforts. A stunning conclusion for sure. :rolleyes:

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.

We created a number of layout sketches, made prototype mechanisms, and evaluated these in the quite-restrictive sizing volume. It because obvious that scoring in the low FUEL goal would adversely affect our GEAR and climbing performance, so we have chosen to score FUEL in the high goal. We do not intend to focus volume, weight, or design effort on shooting as with the other two mechanisms. This will likely result in a low total scoring potential, but the idea with scoring FUEL in the high goal is merely to edge-out over an alliance that can score a similar number of gears. A small number of points should do the trick.

With that, we have started to model our robot. I will post some screen shots of that soon.

Re: Team 95 2017 Build Thread
 

It is. Thus the score for one trip to the high goal in AUTO being worth 10 points.

I wasn't clear that each line represents on 'trip' or one 'activity.'

Re: Team 95 2017 Build Thread
 

First chunk of CAD work is done. We don't mind if you take inspiration (or copy) any piece of the design, just cite your source please! :)



Still two major mechanical subsystems to go.

Re: Team 95 2017 Build Thread
 

Thanks for doing this again. Your 2015 arm concept basically saved our season.

Re: Team 95 2017 Build Thread
 

Always happy to answer any questions people have, too.

:D That's a big reason why we do this!

Re: Team 95 2017 Build Thread
 

Thanks for putting this thread together! It is my favorite thread of the season every year, best of luck!

Re: Team 95 2017 Build Thread
 

I see some 1.25"ish cylinders in each corner of that frame....are we looking to avoid being pushed around by lifting the whole robot?

Re: Team 95 2017 Build Thread
 

I'm playing the "figure out what that cylinder does" game right now, and I'm batting about 50%.

If I'm guess correctly, that's going to be a lot of air usage per cycle.

Re: Team 95 2017 Build Thread
 

So the pair of overlapped cylinders from green to yellow are probably to tilt the yellow bit down to ease the gear entry from the loading station. The four long stroke, small bore cylinders (plus linear rods!) from red to (probably) green are either to get the gear mechanism over the bumper into the wall for loading a gear, or maybe for putting it in place? There's the sideways one under the gear to pivot the blue wings open/closed on those hinges, I'm assuming that one has a bushing instead of a pin in the end of the cylinder.

And then the four in the corners of the chassis which are probably brakes.

That's definitely a lot of air consumption, even if you're regulating down since most of those probably don't need 60psi.

Re: Team 95 2017 Build Thread
 

No... Never... We totally haven't done this before and won a Creativity award for it...

Winner winner, chicken dinner.

So, it 2014 we had a robot with a similar air setup. 4x spring-return cylinders for brakes, 2x air cylinder ball shifters, and then eight(8) 3/4inx6in cylinders to actuate the four panels of the robot (see below). We used the 9% duty cycle Viair with a fan running over it (the fan is a TREMENDOUS help) and 6x of the small metallic Clippard tanks for storage. We didn't have any air consumption issues that year. For this year, we're looking at fewer air cylinders with shorter strokes (but similar bores) and hopefully a better compressor. I anticipate success!

2014 Robot:

Re: Team 95 2017 Build Thread
 

I don't do a lot of linear mechanisms like it, but I'm mildly concerned about your 4 piston extend-o thing binding up the linear rods. The ratio of bearing distance to top-to-bottom distance seems dicey with the off-center placement, but looks like it should be inside the standard 2:1 ratio. The bearing distance to side-to-side distance definitely isn't 2:1, so you could have a problem there, though it'll help if the green bit is a little flexible.

With 4 pistons pushing like that, I think it'll move eventually once pressures equalize, but if one pressurizes sooner, it could bind things up until the others catch up sufficiently. Best make sure all the lines are the same length.

Re: Team 95 2017 Build Thread
 

Points well taken. Plumbing equal-length tubing might work well, or spending a little time tuning each air cylinder with a flow controller.

Re: Team 95 2017 Build Thread
 

CAD continues to inch forward as we spool up to start fabrication this week.



We've purchased the Tormach Tooling System collet and holders for our CNC knee mill. A nice little upgrade to take Z-height adjustments out of the equation.

We have also decommissioned two old robots. We were running out of space to store them, and we will be scavenging parts from them to build a practice robot without breaking the bank (I hope).

Re: Team 95 2017 Build Thread
 

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

Re: Team 95 2017 Build Thread
 

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?

Re: Team 95 2017 Build Thread
 

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.

Re: Team 95 2017 Build Thread
 

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!

Re: Team 95 2017 Build Thread
 

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

Re: Team 95 2017 Build Thread
 

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.

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.

Re: Team 95 2017 Build Thread
 

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

Re: Team 95 2017 Build Thread
 

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

Re: Team 95 2017 Build Thread
 

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.

Re: Team 95 2017 Build Thread
 

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

Re: Team 95 2017 Build Thread
 

No worse than when a robot gets pushed sideways.

Re: Team 95 2017 Build Thread
 

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.

Re: Team 95 2017 Build Thread
 

Sick robot bro

Re: Team 95 2017 Build Thread
 

Assembly of the practice robot begins!

Re: Team 95 2017 Build Thread
 

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.

Re: Team 95 2017 Build Thread
 

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.

Re: Team 95 2017 Build Thread
 

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!

Re: Team 95 2017 Build Thread
 

And this is how CD cancer starts..

Re: Team 95 2017 Build Thread
 

Every team runs things differently. FRC does not dictate roles for mentors or students. I happen to do most of the modeling for 95. We shall leave it at that because there are many other threads discussing this particular topic.

Thank you for reading, I'm glad that you enjoy it!

Re: Team 95 2017 Build Thread
 

Started off with a minor disaster. We had a hex bearing come in with the hex bore not concentric, visibly, with the outer race. Very weird to diagnose.

Moving on... parts! Parts are getting made about as fast as we can stand.



We use a CNC plasma cutter, then sometimes a CNC mill, to make a majority of our components. Then we bend them up on a manual finger brake. Even rookies can get the hang of it quickly!



Practice robot drive base is together. Wiring shall start tomorrow!

Re: Team 95 2017 Build Thread
 

While those are quite nice close up shots of your robot, I'm not quite sure what I'm looking at in particular.

Re: Team 95 2017 Build Thread
 

First shot is an over-all of the parts we've blanked and (some) bent so far. These include nearly all of our gear-handling parts and chassis parts.
Second shot is the belly pan of the robot.
Third is the practice robot's drive base.

Re: Team 95 2017 Build Thread
 

Bonus image.



I've been told that I might have played too much West Point Bridge Designer...

Re: Team 95 2017 Build Thread
 

No, it should not concern you.

Different teams run things in different, equally valid ways. The community would be a better place if people understood that was not only a good thing, but part of what makes FIRST great.
_

James, I might not be working with a team this year, but to echo earlier sentiments this thread is always a highlight. It's been very interesting to see you and your team evolve in design. I'm just sad I've never gotten a chance to see one of your robots in person!

Re: Team 95 2017 Build Thread
 

This is our first year using vex planetary gearboxes. I see you have mounted one directly to your intake shaft. We never thought to do this. How do they hold up to being mounted like this? Does repeated shaft deflection put undo stress on the gearbox? Any weird loading issues?

Re: Team 95 2017 Build Thread
 

I am with you on this one. Myself and other mentor for the team help out with the design of the robot in Inventor due to the fact that our school hardly teaches 3D modeling to a degree in which the student can have the design done before the robot can be built. Normally after the season we have students design any of Off-season robot that is thought of.

Re: Team 95 2017 Build Thread
 

Makes a lot of sense to me. I taught myself Solidworks for an off-season project which definitely made it easier going into the build season. But, still there are a lot of different things that you need to understand from an engineering perspective that cannot be easily taught to a student who is also balancing a heavy school work load.

Re: Team 95 2017 Build Thread
 

Thanks!

We've used this sort of setup before, but we make sure that the coupling of the output shaft is rigidly coupled to the cross shaft so the transmission output shaft isn't cantilevered.

In general we've found that the VP gearboxes are quite robust if a bit of care is taken in their mounting and assembly. This might mean NOT mounting them super-rigidly to prevent slight mis-alignments from putting a lot of load on the bearing package.

We do teach CAD in the offseason so that our kids are familiar with how it operates and what problems it can be used to solve. However, we've found it to be remarkably more fun and productive for the students to make prototype and mock-up subsystems while I turn their discoveries into something manufacturable.

We also use CAD heavily. Cardboard Aided Design. Which is considerably more accessible and intuitive to most students than the other CAD. It plays into our sheet-metal-heavy design repertoire nicely.

Re: Team 95 2017 Build Thread
 

I totally agree with this.

I'm still trying to balance how much is healthy for students to be hands off and how much are mentors having fun and using "teaching experience" for just doing what they want.

Having 15+ years in various CAD environments, I know the time involved when you get down to the small details of a design that's never been built. Companies spend months to years designing something this complex and we give the students 6 weeks.
Key question for myself is "Am I doing this to help them learn or because I want to win?".

Re: Team 95 2017 Build Thread
 

This is a good thread. Team 95 is nice enough to share their designs and progress every year. They are willing to help other teams (like mine) by answering questions. Can we please stop talking about the mentor-student involvement dead horse here. If everyone continues to chime in about this, the thread will devolve because EVERYONE has an opinion about this. It will cease to be helpful.

If you want to talk about this more, please please start a new thread or go to the countless other threads on this topic. Please don't respond to this message.

Re: Team 95 2017 Build Thread
 

Looking good James!

What I love most about these threads is you see how 95 has developed while iterating their own ways of building their robot(s).

Can't wait to see it!

Re: Team 95 2017 Build Thread
 

Quick question, are those bolts-with-washers on your drive axles to hold the bearings in place in the side plates? And are you using flanged or non-flanged bearings in the drive?

Re: Team 95 2017 Build Thread
 

Good question!

The bearings are flanged, and the flanges are on the outside of the drive pod. On either side of the flange is a Pem nut with a bolt and washer that retain the bearing in the side plate. The axles are all live axles with spacers between the side plates and a bolt+washer on either side of the flanged bearings to keep them located.

It is a little convoluted, but it offers some advantages:
-We can replace bearings with axles in place, and without a press (not that we've needed to...)
-The axles' bolts can be made very tight without side-loading the bearings like many dead-axle setups do
-The bearing is huge, which gives the side plate a lot of bearing area
-Fabrication is easy for us, we make side plates and axles then bolt everything together! The holes are a single setup on a mill, and the axles are cut to length on a chop saw, then drilled and tapped in a lathe (though this could be done free-hand).
-The live hex shaft setup offers great packaging options as to where we locate sprockets, chain, wheels, etc and responds well to wheel/drive/location changes.

We used this style last year and were quite pleased with it. We converted from #25 to #35 chain and swapped around where we located colson and pneumatic wheels a few times; we were able to do so with little pain. It held up wonderfully to 4 events of hard driving, needing no significant maintenance besides occasional chain tension adjustment. That usage included semi-finals play and two finalist runs, one of which we played defense against some rugged teams including 1519 and 319.

Re: Team 95 2017 Build Thread
 

I like this method. I saw it on one of 254's robots and wasn't sure if they had just threaded a hole or used nuts. I hear that chains tend to stretch a little, but we've never witnessed it in one of our robots. How would you tension (or re-tension) a chain with this configuration?

We were considering using this method with our winch setup instead of our usual t-slot, but couldn't figure out how to tension it without adding complexity.

Re: Team 95 2017 Build Thread
 

Tensioning will always add *some* complexity to the system, but it doesn't take too much.

Last year I designed a little part we called the 'ninja ghost' to do out chain tensioning. See below. It's a special cam profile that rotates to tension the chain while passing the chain's tension force through the center bolt, resulting in near-zero net torque on the tensioner. The recess in the ghosts' faces fits a 10-32 nut, making the tensioner a single-tool adjustment.



This year we're using a delrin rod running over a bolt to simply push the center of the chain. It's crude, but quite effective.

Climbers respond well to very basic tensioning methods because only one side of the chain is ever under load, generally speaking. Thus off-the-shelf methods designed to always work on a chain's slack side are quite effective. These methods do NOT work well on drive systems that are reversed. I would think a simple plastic guide bolted through a slot or series of holes pushing on the slack side of your chain would work just great.

I feel obligated to point out that chains don't stretch in the technical sense that the chain is undergoing plastic deformation in tension. Each pin and roller pair wears just a tiny bit, and this added slop makes the chain effectively longer. To that end: good lubrication and light loading will help keep chains from elongating over the course of a season. We use PTFE-based dry film lubricants, they are perfect for FRC applications like chain and open gearboxes.

Re: Team 95 2017 Build Thread
 

Seems like you're keeping some pretty big keep-outs above each drive rail - what's the thinking there?

Re: Team 95 2017 Build Thread
 

Another good question.

-I haven't shown the battery in a rendering yet, so I'll fix that...
-The drive pod standoffs are great pick-up points to lift the robot by, so I like to keep the corners of the drive pods accessible
-I don't model 100% of the components, so I like to leave a reasonable margin for things like air cylinder fittings, which can stick out an inch or so
-I try to keep mechanisms to be as big as they need to be, but not as big as they can be



To expand on that last point - in prior years we've made some bad design compromises thinking 'our intake should be as big as possible' or something along those lines. It's been painful to work around such dramatic compromises later in the season, so I try to build in some wiggle room.

This policy has also kept us under-weight from 2010 on... which has been really nice.

Re: Team 95 2017 Build Thread
 

Per request, I've uploaded the ninja ghost model to CD media: https://www.chiefdelphi.com/media/papers/3342

The principle of operation is that the helix surface is always normal to the center pivot bolt axis, so the reaction force of the chain doesn't exert a torque around it. The anchoring bolt can go through a curved slot, as it did in our 2016 robot Kovaka seen below. Alternatively, the anchoring bolt could go through a match-drilled hole once tension is drawn, or through a series of holes. Implementation can be varied to your hearts content! In a slack-side-only implementation it would be feasible to only use the center bolt, especially if there is a good frictional material between the plastic cam and whatever it is anchored against.



Good luck! If you do decide to use/copy/modify/whatever the design, just cite your source! (and definitely continue to call it a ninja ghost)

Re: Team 95 2017 Build Thread
 

Shooter prototype is pretty well sorted at this point. 1:1 775 Pro motor with a 2 1/2in colson wheel, approximately 1/4in of compression.



Assembly and fabrication is progressing nicely. Starting with a little bit of welding.




Practice robot's gear receiver assembly is together.



And then mounted!



It works pretty okay so far!

Re: Team 95 2017 Build Thread
 

Darn 5-image limit...

The practice robot is starting to get its guts put in.



Since we've elected to build a practice bot this year we have also decided to dress up our competition robot. Time for paint!



We also had, for the first time, a bad hex bearing. Hex was broached off-center. Very weird...

Re: Team 95 2017 Build Thread
 

Looking pretty cool so far!

Can I ask where you got those CAN wire connectors and how you secured the wires in them?

Thanks.

Re: Team 95 2017 Build Thread
 

Female Housing
Male Pin
Male Housing
Female Pin (Socket)
Crimper
Extractor


There is probably a cheaper place to get them, but McMaster works for us! These connectors worked very well for us last year.

Re: Team 95 2017 Build Thread
 

Have you indicated a shaft in the bearing? How far out of center is it?

Re: Team 95 2017 Build Thread
 

We did not indicate it. One could put a small section of hex shaft in the bearing and watch it wobble while turning it by hand. I would guess around 0.03in out of concentricity at least.

Re: Team 95 2017 Build Thread
 

Hey James, glad to see the thread coming back again.

Out of curiosity - do you plan on holding a gear to start? I'm not seeing how you will be able to since the release mechanism goes outside the frame perimeter.

Re: Team 95 2017 Build Thread
 

The release mechanism is within the perimeter at the start of the match. It only goes beyond (if at all) once the match has started as they release the gear on the peg. I don't see how this is an issue?

Re: Team 95 2017 Build Thread
 

Ah, upon examining it further the whole mechanism slides in and out.

Re: Team 95 2017 Build Thread
 

Bingo. It slides out 5 inches so that we get the same geometry to score with if FUEL is piled in front of the peg.

Re: Team 95 2017 Build Thread
 

Definitely an interesting combination of colors. What made you guys choose this particular combination of colors?

Re: Team 95 2017 Build Thread
 

What are you doing to get paint to stick to your aluminum? Zinc chromate? Scuff and pray? Or did you find another method that works? I've tried a few over the years and only zinc chromate has worked but I hate paying for it.

Re: Team 95 2017 Build Thread
 

Our Official logo/shirts:



A thorough degrease with acetone and then sprayed with rustoleum paint+primer. I run a side-business making a variety of custom things, and we've had good luck with that approach.

Re: Team 95 2017 Build Thread
 

[quote=JamesCH95;1637732]Our Official logo/shirts:

Ah, now I see why, it'll be interesting to see how it looks when built.

Re: Team 95 2017 Build Thread
 

I'm hoping that the robot will look a little something like this:



CAD is nominally done at this point.

Re: Team 95 2017 Build Thread
 

Practice robot is progressing:



Laziest climber spool construction ever:

Re: Team 95 2017 Build Thread
 

Are those hex shafts just larger pieces of hex that have been broached out?
Cause that would be really useful to use...

Re: Team 95 2017 Build Thread
 

I'll do you one better:

1/2in ID, 3/4in OD hex tube

3/4in ID, 1in OD hex tube

They generally have a great slip-fit to each other and to the 1/2in solid hex shaft that we all know and love.

Re: Team 95 2017 Build Thread
 

Hey, man, you don't speak for me. Some of us are still fighting against the Hex Shaft Monoculture that's destroying the keyway spirit that made FRC what it is.

Viva La Roll Pin!

:p

Re: Team 95 2017 Build Thread
 

One better indeed!!!

This is helpful.

Re: Team 95 2017 Build Thread
 

Chained the practice robot's drive train and started mounting pneumatic storage tanks.



Chained the winch and installed some floating tensioners.



The guts have power! We're starting all the IT overhead, Talon addressing, etc. Getting a powered on robot before week 4 is pretty good for us.



We've been having a few assembly issues, nothing a few washers can't fix, but it is certainly slowing us down a little.

Re: Team 95 2017 Build Thread
 

Extremely excited to see this robot

Re: Team 95 2017 Build Thread
 

Thanks! We look forward to showing it off!

Punched out bumper parts on my CNC router.



We utilize bridging to keep setups simple. Easy to model in HSMWorks.



After slicing them out on a band saw, plus a quick touch-up with a palm sander, they're ready for beveling. I have a DeWalt chop saw that uses a super bright LED to cast a shadow of the blade on the part. Supremely better than a laser and provides great illumination. Cannot recommend strongly enough!



Look at all those layers of Birch plywood...

Re: Team 95 2017 Build Thread
 

Assembly, plumbing, and wiring continue:



And the gear mechanism works nicely under its own power.

We intend to open up flow control valves and see how fast we can push things.