We were thinking about using a hex shaft with wheels. However, we’re not too sure what the best way is to secure the wheels on the shaft (hex shaft collars + hex hubs seem a bit too involved/expensive)
I was looking at Team O-RYAN’s Ri3D video and the wheels seem to be secured without much setup.
We are a rookie team so we don’t have a lot of resources… Nor do we have scrap material from previous years. Anything we want to build we would have to order.
Is there an easy way to build this pickup?
They built their intake using very basic parts. To build an intake like theirs, I would pickup some aluminum square tubing from a local hardware store, shaft (preferably hex shaft from VEX), shaft collars, wheels that fit the shaft, bearings that fit the shaft, sprockets, chain, and a geared motor.
You can PROBABLY do without bearings
Hex shaft collars are a great way to go! What wheels are you using? Some wheels come with a hex built in, if not, a hex VersaHub from VEXpro would be a great fit!
Check out Banebot wheels. They are cheap and made to take hex shafts. or AM star tube.
Hex shaft, a couple of hex bearings, two Banebots wheels, and some PVC to use as spacers to hold the wheels in place–it’ll last you all season and is about as cheap as a mechanism gets!
Still pretty cheap to get hex shaft collar clamps from Vex too!! 
The CAD to our intake is located here: http://www.robotin3days.com/ri3d-1-0-roller-intake-cad/
It was very easy to setup. We completed the design and fabrication in under half a day between 2 people. The hardest thing would be to fabricate the C Channel that boxes the Modulox Channel. This could be done with any angle stock or correctly sized C Channel.
The Modulox channel made it really easy to tune the mechanism. We just adjusted the position of the entire assembly, pneumatic pivot point and roller assembly in the slots until we gripped the ball effectively. We are able to approach the ball off angle and quickly acquire due to the wide front.
I hope to produce a video walk-through of this mechanism soon.
1.50 OD PVC tube with elbows in the shape of a rectangle. The ball should fit through the rectangle.
a length of 1.5 pvc tube with end caps. lots of wide rubber bands around the tube. Drill the ends with a under size hole. Press a .500 OD shaft through the end caps threads drill holes in the rectangle for the roller and shafts. Use a bushing through the retangular pvc part. Chain up a motor to the shaft.or use the Versaplantary transmission are good to use at 15:1. Or the AM motor with planetary that comes in the kit are good too.
PVC tube is a great material to make mechanisms out of. It’s strong, light weight, cheap and easy to cut with a saw. We use drilling screws to a fix the tubes and joints together instead of glue.
So I should get
Aluminum tubing from local aluminum shop (http://www.alustock.ca/Square-Tube-SC-1x0.125-AMR1465)
AndyMark or VexPro hex shaft (http://www.andymark.com/product-p/am-2291.htm?CartID=1)
2 BaneBots Wheel, 2-7/8" x 0.8", 1/2" Hex Mount (http://banebots.com/pc/WHB-HS4-298/T80P-295BA-HS4)
2 BaneBots Wheel, 3-7/8" x 0.8", 1/2" Hex Mount (http://banebots.com/pc/WHB-HS4-398/T80P-395BA-HS4)
10 (?) Clamping Shaft Collar - 1/2" Hex ID (http://www.vexrobotics.com/shaft-collars.html)
We have some geared motors (http://www.andymark.com/product-p/am-0915.htm) coming as a part of FIRSTChoice. What should we do in terms of sprockets: 25 series (http://www.andymark.com/product-p/am-2182.htm) + (http://www.andymark.com/product-p/am-0749.htm)?
Putting the shaft through the aluminum tubing - how is this done? Is there enough space for hex bearings?
I would get the shaft and wheels from VEX just to minimize the vendors for convenience.
Well he might be using the BaneBots voucher
But yes, get the hex shaft from Vex…(cheaper)
I’m a bit concerned about bending a 1/2" 7075 hex shaft over a 26" span. We’ve done it before. So, I’m considering using a 3/4" hex shaft. Am I out of my mind here?
Also, I’d like to build a pickup very similar to Ri3D 1.0, but I noticed, that robot didn’t have bumpers. That’s why it works so well. Bumpers make a BIG difference. I did some “Crayola CAD” on the geometry of it, and I can’t find a way to avoid A LOT of compression on the ball during the point at which it goes over the bumpers, while still maintaining good contact and forward reach when the ball is on the ground. Any ideas there? Maybe we’ll be okay with a 13" gap in the bumpers, which should help some.
Interesting question. Just for sake of not popping balls we have been considering rollers instead of wheels. This would allow you to only exert forces on the end of the shaft too.
I would not recommend using the churro tube for sure, it’s not designed for such stresses.
I feel like anything that would bend a steel hex shaft, even 1/2 inch means you are over compressing the ball and I’d be concerned about popping it. We bent what I think was brass today when we over compressed on one of our prototypes.
Also gonna throw out there that the banebots wheels are insanely good at gripping this ball. In my, walk around the shop and touch stuff to the ball, they were by far the best. Didn’t have any VEXpro wheels around though, I’ve heard good things about them as well.
Can someone help me on these?
We found the shaft flexed quite a bit. We were concerned about yielding on a impact or fatigue over time. We created a center strut support in our design. It was just another piece of channel that we sectioned to slide into place.
This provide seemingly sufficient support and significantly reduced our concerns. This could have just as easily been 2 off center supports to further alleviate concerns.
