Originally Posted by Cherry254 (Post 1590415)

Team 254 Presents: Dropshot Technical Binder. The binder can be found here. If you have any questions or want more specifications, feel free to ask!

Originally Posted by Michael Hill (Post 1590518)

Awesome robot as usual.

I've been curious about your turret gear. It looks similar to 1114's from 2012, but from my guesstimates, it's 20dp @ 16.1" Pitch Diameter whereas 1114 had a much larger geartooth (something like 10-12dp). One of my main concerns is actually having our waterjet sponsor cut teeth that small (I've been contemplating turrets lately). Was it relatively easy for your sponsor to do or was there anything special you had to do to the gear design to make it easier to manufacture? I'm guessing going to 0.125" aluminum made it easier, but is that enough?

Originally Posted by caume (Post 1590520)

Also, why do you only use two CIMs in your drive? You need moar pushes

Originally Posted by Michael Hill (Post 1590518)

Awesome robot as usual.

I've been curious about your turret gear. It looks similar to 1114's from 2012, but from my guesstimates, it's 20dp @ 16.1" Pitch Diameter whereas 1114 had a much larger geartooth (something like 10-12dp). One of my main concerns is actually having our waterjet sponsor cut teeth that small (I've been contemplating turrets lately). Was it relatively easy for your sponsor to do or was there anything special you had to do to the gear design to make it easier to manufacture? I'm guessing going to 0.125" aluminum made it easier, but is that enough?

Originally Posted by bigbeezy (Post 1590524)

would a waterjet be able to do 20DP gears?

Originally Posted by Dan Petrovic (Post 1590526)

Can I get some more information about the 2" OD surgical tubing that was used on the intake? After searching for 2" OD black rubber tubing on McMaster, the only result given was nitrile tubing with a 60A durometer hardness. Is this the same stuff?

Bringing the OD down to 1.5" (still black opaque) returns latex tubing with a hardness of 40A, more in-line with what Banebots uses on their wheels.

Is there another supplier where 2" latex tubing is available?

Originally Posted by Michael Hill (Post 1590518)

Awesome robot as usual.

I've been curious about your turret gear. It looks similar to 1114's from 2012, but from my guesstimates, it's 20dp @ 16.1" Pitch Diameter whereas 1114 had a much larger geartooth (something like 10-12dp). One of my main concerns is actually having our waterjet sponsor cut teeth that small (I've been contemplating turrets lately). Was it relatively easy for your sponsor to do or was there anything special you had to do to the gear design to make it easier to manufacture? I'm guessing going to 0.125" aluminum made it easier, but is that enough?

Originally Posted by sanddrag (Post 1590566)

I've only had a chance to skim it, but once again, very nice looking, and a valuable resource to other teams like ours. Thanks for releasing this.

I'm curious to know what pneumatic wheel hubs those are, or if you made them. Are there any additional photos of the wheel hubs?

Also, the PDF text looks to have exported as a raster image rather than as vector text. Not sure if you meant to do that.

Originally Posted by caume (Post 1590520)

What do you use as a thrust bearing for your turret? Also, why do you only use two CIMs in your drive? You need moar pushes

Originally Posted by Ashwin Adulla (Post 1590584)

We have 7 bearing assemblies along our turret gear which you can see if you look closely on page 16. Each bearing assembly consists of 3 ball bearings in the following order: a large bearing, a small bearing, and a large bearing (I do not know the exact bearing size). Each bearing is separated by a small shim and is lined up along a 10-32 screw with a locknut threaded at the bottom of the screw. The locknut is not tightened to its fullest extent in such a way that as the two large bearings sit upon the top and bottom of the plate connecting the two sides of the superstructure, they are able to slide along the plate's surface in addition to the small bearing with can rotate freely as it contacts the inner edge of the plate.

Originally Posted by jkelleyrtp (Post 1590556)

How was your experience with mechanum wheels for an intake? Are you likely to use them again in the future?

Originally Posted by s5511 (Post 1590563)

How did you guys have 3 positions on your utility arm using pistons? During matches, it looked like there was an all the way up, slightly raised, and completely down position for the arm.
Also, are the 1.5'' bore pistons which raise the utility arm mounted directly to the arm? It doesn't look like in it your pictures, but I can't exactly tell.

Thanks!

Originally Posted by seans341 (Post 1590595)

Thanks for posting this! I noticed that turret compatibility was a significant factor in the overall design process. What did you notice about the game that made a turret so appealing?

Originally Posted by z_beeblebrox (Post 1590523)

They've got 4. See the image on page 10. The motor in the gearbox render is hidden to show the other components.

Originally Posted by Cherry254 (Post 1590596)

The Utility arm can go into 4 positions using deployable hardstops and kickstands. Its 4 states were drive mode, Low Bar mode, Starting configuration and hang mode. The pneumatic cylinders mounted to the plates extending down at the bottom of the arm as seen on page 21. Below see the deployable hardstops.

Originally Posted by caume (Post 1590623)

I meant to say two CIMs per side, four total. Why not use six?

Originally Posted by caume (Post 1590627)

Why did you decide to go with #35 chain this year, instead of the usual #25?


Why did you use a servo in place of the pistons you used in 2014? I'm guessing it was for theoretically infinite hood positions, but I would think 4 or so would be enough. I guess it could possibly require some motor speed modification, but I would think that would be fairly easy...


Isn't a bag motor with a 5-stage gearbox a bit overkill...? I would think having some mechanism like a piston ball loader would be enough, or at least a bag motor with a (planetary?) gearbox with fewer stages

Thanks in advance for any response.

Originally Posted by microbuns (Post 1590628)

I'm curious where the ball sat while the turret was swiveling, and how it avoided the flywheel as well as the chassis during rotation. This was our teams biggest problem with turreted shooter who went under the low bar.

Originally Posted by Tal_Esh (Post 1590637)

Any link or properties about the Fairlane wheels? Saw those on 1241's shooter as well but couldn't manage to find them online.

Originally Posted by s5511 (Post 1590635)

I'm curious as to why you guys use chain instead of belts on your drivetrains. Is there any specific reason why you guys prefer chain?

Originally Posted by apache8080 (Post 1590648)

What other wheels did you guys try out for the flywheel?

Do you guys use laser cut wood for majority of your prototypes? I assume that this makes prototyping easier and more accurate.

When is your code going to be released?

Thanks for this incredible resource.

Originally Posted by Ashwin Adulla (Post 1590658)

We bagged and tagged our robot with 2 4" Colson wheels acting as our shooter. At CVR, we used 4 4" Colson wheels. At SVR and Champs, we used 2 4" Fairlane wheels with safety wire wrapped around it to stop it from expanding a significant amount past 5000 rpm.

Yes we did use a laser cutter for prototyping with wood and it greatly aided our prototyping process as we were able to quickly CAD and test different variables for our flywheel shooter (pg 13) such as hood angle, pulley ratios, ball traction, and moment of inertia. In addition we did use the laser cutter to test out different intakes and also to cut the hubs for our mechanum wheels.

As for the code, our programming team is performing a code clean and is planning to release it soon.

Originally Posted by Ashwin Adulla (Post 1590658)

Yes we did use a laser cutter for prototyping with wood and it greatly aided our prototyping process as we were able to quickly CAD and test different variables for our flywheel shooter (pg 13) such as hood angle, pulley ratios, ball traction, and moment of inertia. In addition we did use the laser cutter to test out different intakes and also to cut the hubs for our mechanum wheels.

Originally Posted by Kevin Sheridan (Post 1590666)

Heres a picture of my favorite prototype this year.

Originally Posted by TheModMaster8 (Post 1590667)

could i get a reply to my question??:confused:
It was easy to miss :)

Originally Posted by bigbeezy (Post 1590676)

For the Nexus 5 you have for vision, did you have to power it off of the robot? If so, did you just power via the USB or someother way?

Originally Posted by roboruler (Post 1590678)

Internal Batteries are allowed for COTS computing devices. They did not open the phone up and remove the battery, instead they just ran a USB cable from the robo-rio to the phones charging/data port.

Originally Posted by apache8080 (Post 1590662)

Why did you guys switch from the Colson wheels to the Fairlane wheels?

Originally Posted by ThemisH (Post 1590689)

We saw that the Colsons weren't effieciently transferring energy to the ball, mostly due to not having a high enough coefficient of friction. Our 2014 robot Barrage used two 775 motors on the flywheel just like Dropshot, and yet it was able to launch a ball that was several times more massive than the Stronghold boulders. Barrage used Fairlane wheels, so we tried them on Dropshot and they greatly increased our power output, so we stuck with them. If you compare videos from CVR to SVR/Champs, the power difference is very noticeable.

Originally Posted by bigbeezy (Post 1590676)

For the hood, it looks like you milled out a slot/track. Did you just use track rollers from McMaster or something different? How did you insure that the motion was smooth and didn't bind/be too lose and wobble?.

Originally Posted by apache8080 (Post 1590693)

Thanks for the information. It is always great to see how elite teams iterate their designs.

On the subject of iterations, why did you guys go away from gas shocks in the hanger.

Originally Posted by thatprogrammer (Post 1590711)

Based on your technical binder, it seems that you ran the neoprene wheels directly on hex shaft. How did you manage to do this?

Originally Posted by waialua359 (Post 1590948)

Travis, I had heard that you are the lead on the technical binder. Is this true?
Kudos to the mentors and the students who worked on this.
The most impressive part besides the actual robot with its features, is that you have it really condensed yet very informative on the whole design process, decision making and explanation of each of the systems.

Originally Posted by waialua359 (Post 1590948)

Travis, I had heard that you are the lead on the technical binder. Is this true?
Kudos to the mentors and the students who worked on this.
The most impressive part besides the actual robot with its features, is that you have it really condensed yet very informative on the whole design process, decision making and explanation of each of the systems.
Cory, our former mentor who was with my alma mater Team 4158 cut a lot of gears with a jet sponsor. Our team needs to get on board with ours soon and I need to research more about different nozzle sizes and what they can cut. Skies the limit.

Originally Posted by Torrance (Post 1590974)

The technical binder has always been a student led and written project as the students who compose it use it as practice for their presentation in the pits to Technical Award Judges. I wrote the binder in 2014 and 2015 and Travis did some editing to keep it concise and relevant. In 2016, Technical Director Alex Cherry and Documentation and Submissions Director Matt McDonald wrote it with me (now 1st-year mentor) serving as the editor.

The binder also required a lot of work from our Media Director Peter Feghali to do the renders, layout, and aesthetics.

Originally Posted by waialua359 (Post 1591048)

Thank you to you and Travis for sharing. You mentioned some other mentors who helped who I never heard of or met.
Teams like yours are an inspiration to many, including us. As a follow up, it would be cool to hear about the team structure and the mentors that support both the robot (many who we know) and the non-robot technical support that you folks have.

Originally Posted by waialua359 (Post 1591048)

I hope this is a project you folks continue to do and share post-season annually.

Originally Posted by Michael Hill (Post 1591082)

How do you guys do project management? Do you have design/concept reviews? What tools do you guys use to keep organized?

Also, somewhat off topic, we used a modified version of the 254 part management tool (cheesy parts) this year and it was fantastic. It really helped us especially get orders put together. Instead of writing orders down on a marker board or a piece of paper that can get lost, it was great to have everything organized the way it was.

Originally Posted by Torrance (Post 1591079)

Of the people I mentioned, only Travis (and sorta me) are mentors. Alex, Matt, and Peter are Directors on our student leadership team.

The team leadership structure is divided amongst the mentors and student leadership team which consists of Directors that lead sub-teams of other students and Captains that serve as project managers on particularly large tasks.

The team certainly has a lot of mentors, but this is essential for managing the 100+ students working on multiple projects. Our mentorship is unofficially divided into technical and non-technical mentors.
Going off of our Mentor Page, the following are technical:
Travis Covington, Pat Fairbank, Cory McBridge, Tom Bottigleiri, Leigh Pauls, Kevin Sheridan, Paul Ventimiglia, Dan Judnick (mostly VEX), Kenneth Lloren, Jared Russel, Colin Wilson, Nick Eyre, Trevor Kearse. Also myself and fellow SCU student Mani Gnanasivam.

Nontechnical mentors include: Esteban Parker, David Wilson, Nick Hammes, and faculty Peng Yav and Brad Lindemann.

Not all of the mentors attend every build or every competition.


The student leadership team breakdown (recently updated for 2016-2017) is also on our website. As you can see, 1/2 of the positions are non-technical in nature.

The Directors closely collaborate on a lot of projects. For example, this technical binder was written by the FRC Technical Director with the help of a technical mentor (me or Travis). Then the Documentations and Submissions Director and a nontechnical mentor or 2 helped edit and clean up the bullets before giving it to the Media Director who's sub-team did the renders and formatted it using Word into the final document.




We plan to! Creating the technical binder is a great learning experience for all the students involved, in addition to being a useful resource for judges or other teams.

Originally Posted by waialua359 (Post 1591086)

I vaguely remember seeing this previously. Can you share the link?

Originally Posted by Michael Hill (Post 1591082)

How do you guys do project management? Do you have design/concept reviews? What tools do you guys use to keep organized?

Also, somewhat off topic, we used a modified version of the 254 part management tool (cheesy parts) this year and it was fantastic. It really helped us especially get orders put together. Instead of writing orders down on a marker board or a piece of paper that can get lost, it was great to have everything organized the way it was.

Originally Posted by Jay O'Donnell (Post 1591105)

Andrew (or other 254 members), would you mind giving a general timeline of your season? Such as when certain robot decisions and milestones occurred?

Originally Posted by DinerKid (Post 1591084)

Awesome write up.

I'm very intrigued by the safety wire that you used on the flywheel.
Would you mind elaborating on the reason you use it, process for installing it, and perhaps a picture?

Thanks
~DK

Originally Posted by sanddrag (Post 1591131)

Andrew, you say you had build days on MWF and Sat. Did the team still meet on the other three days of the week or did you really meet only 4 days per week?

Originally Posted by Cory (Post 1591140)

We were very conscientious about only meeting those 4 days until week 6. We met more during the final week of build, went back to the 4 day schedule, and then did more like 5-6 as we got deeper into the season. We tried to make sure we left at 11 pm at the latest most nights, which we did a reasonably good job of during the build period and a less good job of as we got into competition season.

On the whole it was much better than previous years in which we worked 7 days a week the entire season, often until 2 am or later every Friday/Saturday.

Originally Posted by Michael Hill (Post 1591144)

What prompted you to do that? Change of venue? Mentor/student burnout?

Originally Posted by Jay O'Donnell (Post 1591105)

Andrew (or other 254 members), would you mind giving a general timeline of your season? Such as when certain robot decisions and milestones occurred?

Originally Posted by aphelps231 (Post 1591993)

Awesome robot guys.

Will there be a build season blog released for this year?

Originally Posted by Torrance (Post 1591163)

This a question we get asked a lot and unfortunately we don't do a very good job of documenting this besides the build blog (which was largely incomplete and thus unlikely to be released this year).

Originally Posted by Ashwin Adulla (Post 1591123)

.... the safety wire was wrapped once around the wheel, cut to its length, and then two ends were twisted together and then stuck inside the neoprene so as to prevent it from contacting the boulder. I have attached a picture of the flywheel below.

Originally Posted by bkahl (Post 1591995)

Literally 2 posts above you...

Originally Posted by NWChen (Post 1591161)

How was your experience lasercutting a bellypan from 1/4" thick ABS? I've read that ABS tends to curl and melt rather than vaporize under a laser.

Originally Posted by NWChen (Post 1591161)

How was your experience lasercutting a bellypan from 1/4" thick ABS? I've read that ABS tends to curl and melt rather than vaporize under a laser.

Originally Posted by gc_coxen (Post 1593120)

I may be mistaken but it doesn't look like there are CAMs on your bearing blocks to tension the chain. Did you tension chain or just find an optimal position that was permanent?

Originally Posted by Cory (Post 1593136)

This is the same as last year. We did fixed center to center distance that was the nominal chain pitch plus some fudge factor (I think .015" ish added to each run, but I don't remember for sure off the top of my head).

Originally Posted by Sperkowsky (Post 1593155)

At champs I was doing field reset on Newton and talked to Travis a bit about it. He mentioned that they have a better set up at their school and mostly work there now. I believe he also said they missed giving students the opportunity of working at a NASA facility which is an interesting point I never thought of.

So... yea that's what I have figured out from me digging around. Ill delete this post once someone actually from 254 gives a better response.

Originally Posted by caume (Post 1593419)

Are CADs for Dropshot available anywhere?

Originally Posted by caume (Post 1593419)

Are CADs for Dropshot available anywhere?

Originally Posted by Travis Covington (Post 1590670)

We have no plans to release the CAD of the robot but are happy to answer any questions you have.

Originally Posted by Ashwin Adulla (Post 1591123)

The main purpose of the safety wire, as suggested by Team 1678, was to prevent our fairlane flywheel from expanding a significant amount past 5000 rpm. During prototyping, the fairlane wheels expanded to the extent that we were fearful of testing them out. As a result, the safety wire constrained the expansion of the wheels to a certain diameter which allowed us to ramp up to around 6000 rpm at Champs for taking shots. As for the process of installing them, the safety wire was wrapped once around the wheel, cut to its length, and then two ends were twisted together and then stuck inside the neoprene so as to prevent it from contacting the boulder. I have attached a picture of the flywheel below.

Originally Posted by lnex1357 (Post 1592057)

We are throwing some fairlane wheels on our shooter for an offseason event in place of our colsons. Did you guys use round or flat safety wire and what was the rough OD or width respectively, as I would prefer not to guess and check through a series of McM orders. Thanks so much!

Originally Posted by RoboChair (Post 1593534)

Round safety wire 0.032" diameter. 1678 ran 2 wraps around our wheels. It's a little bit of a tricky process. You must get the safety wire tight and squeezing into the wheel a little and you will almost definitely break some wires in the process of twisting them. Try until you succeed To stuff the twisted wire end into the wheel use a screwdriver or awl to stab into the rubber right next to the twisted end, then stuff it in.

Attempted destructive test of a shooter wheel

Originally Posted by asid61 (Post 1593692)

I felt myself shying away from that wheel...
Out of curiosity, does it explode if you run it without the wire, and if so how did you find out?

Originally Posted by asid61 (Post 1593692)

I felt myself shying away from that wheel...
Out of curiosity, does it explode if you run it without the wire, and if so how did you find out?