Re: Team 254 Presents: Dropshot Technical Binder 2016
 

Here is a picture of my favorite prototype from this year.

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

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

That's awesome :D

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

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

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

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?

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?

Thanks for sharing, I (and my team) learn a lot from these.

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

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.

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

Good to know, thanks!

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

Do you guys do your laser cutting in house? Whether it is or not, I'm curious what make and model of laser you use.

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

We saw that the Colsons weren't efficiently 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.

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

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.

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

For our hood, we did mill out a slot on both hood plates and used what could best be described as a T-slot roller to move along the slot (I have attached a link of a T-slot roller to better visualize how our sector gear was able to move along the slot). In our case, the T-rollers, two on each side, were made out of plastic and turned down on the lathe. While assembling the hood, we did encounter an issue of the motion being somewhat rough due to the friction as the lateral surface of the T-slot roller contacted the inner surface of the slot. To fix it, we simply took a small file and filed down the lateral surface of the roller in addition to cleaning the slot with isopropyl alcohol (we used the same alcohol on the inside of our hanger weldment to ensure the inner tube would smoothly extend out for hanging). As the sector gear did extend past the halfway point on the slot, a slight wobble was noticeable by virtue of the distance between the bottom of the sector gear and the top of the hood plate shortening. However, this wobble was not deemed to be significant concern affecting our shot.

http://el34world.com/Misc/Cnc/images/Img_7561.jpg

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

Initially, the idea of utilizing gas shocks as the means to scale the tower after time had ended seemed like a feasible idea in CAD. When it came to assembling them on the hanger however, we encountered the issue of both gas shocks releasing at different times as was evident in a test which consequently bent the hanger weldment. This problem could have either been attributed to a difference in the force exerted by each gas shock or a difference in force exerted by the pistons with a spring coiled around the rod that were used to compress the gas shocks. We knew that a winch gearbox was both a proven and feasible option, and thus we decided to implement it following SVR.

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

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

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

Which solenoids/manifolds are you guys using on dropshot?

Re: Team 254 Presents: Dropshot Technical Binder 2016
 

We machined custom delrin hubs for each wheel which were able to be pressed on a 1/2" hex shaft.