Star intake rollers

[Bob Steele]

Originally Posted by Ben Martin

Last I knew, Mike Trapp of Waterjet Cutting of Indiana was AndyMark's supplier for this item (they came out with it in 2010 as a method for soccer ball control)--thus the "Trapp" in the name. Mike is a fantastic waterjet sponsor for many local FRC teams and college groups (He sponsored both teams I was previously on, 234 and 1747, multiple times).

Mike is a great supporter of FIRST and students!!
Our team had special intake rollers that we used this year. Mike made them for us and they worked great!!

[marccenter]

Our team had special intake rollers that we used this year. Mike made them for us and they worked great!!

Can you provide some info on your rollers? Were they some kind of metal star with attached stars or something similiar to the AM design which seem to be made of a thin silicon composite? Can you provide a picture on your robot?

[T^2]

Originally Posted by marccenter

Our team had special intake rollers that we used this year. Mike made them for us and they worked great!!

Can you provide some info on your rollers? Were they some kind of metal star with attached stars or something similiar to the AM design which seem to be made of a thin silicon composite? Can you provide a picture on your robot?

I can't speak for 1983, of course, but since our pit was right next to theirs at champs, I got plenty familiar with the stars. They're more or less similar to the AndyMark stars, except they have a .5" hex hole in the center, to go on the hex roller shaft. Apparently it's much easier to water jet a hex hole than it is to broach one in silicone rubber.

[BJC]

Just a pro tip for anyone who might decide to use the AndyMark Entraption stars in the future.

They have a 1/2" square hole through them however, if you try to put them on a 1/2 square shaft they'll easily rotate around the shaft. While it takes some effort, stretching them over 3/4" square yielded great results for us.

[IKE]

Originally Posted by BJC

Just a pro tip for anyone who might decide to use the AndyMark Entraption stars in the future.

They have a 1/2" square hole through them however, if you try to put them on a 1/2 square shaft they'll easily rotate around the shaft. While it takes some effort, stretching them over 3/4" square yielded great results for us.

Warm water with a touch of soap helps them slide easier.

[DonRotolo]

I would think some metal plates to reinforce the hole might be useful. Large enough to grip the central rubber 'disk' and prevent unwanted slippage.

[Bob Steele]

Originally Posted by T^2

I can't speak for 1983, of course, but since our pit was right next to theirs at champs, I got plenty familiar with the stars. They're more or less similar to the AndyMark stars, except they have a .5" hex hole in the center, to go on the hex roller shaft. Apparently it's much easier to water jet a hex hole than it is to broach one in silicone rubber.

You are correct. Same as AM except thicker and longer arms and a hex hole. We had absolutely no problem with any kind of slippage on the hex shaft. Hex hole was slightly undersized. Rubber is about 1/2 inch thick.

[marccenter]

Hex Star Intake Design Concept,

Since I have access to a water jet, here's a concept I developed. Use water jet to cut out alum hex star (0.125 to 0.25 inch) thick. Use on both ends of 1.0, 1.5, or 2.0 inch long star. Attach 6 thin plates (0.5 inch wide by 1.0, 1.5 or 2.0 long) with attached wedgetop, roughtop, or silicone material. Rivet star material to thin plate. Attach thin plates to hex star by super glue? Thoughts? Apologies in advance for using powerpoint as my source drawing tool.

[T^2]

Originally Posted by marccenter

Hex Star Intake Design Concept,

Since I have access to a water jet, here's a concept I developed. Use water jet to cut out alum hex star (0.125 to 0.25 inch) thick. Use on both ends of 1.0, 1.5, or 2.0 inch long star. Attach 6 thin plates (0.5 inch wide by 1.0, 1.5 or 2.0 long) with attached wedgetop, roughtop, or silicone material. Rivet star material to thin plate. Attach thin plates to hex star by super glue? Thoughts? Apologies in advance for using powerpoint as my source drawing tool.

Seems like a lot of work for very little benefit... if you have access to a water jet, you might as well just cut out entire stars out of some rubbery material.

Side note: I wouldn't at all trust superglue to hold aluminum plates together under repeated impact. VHB tape would probably serve you a lot better.

[Bob Steele]

Originally Posted by T^2

Seems like a lot of work for very little benefit... if you have access to a water jet, you might as well just cut out entire stars out of some rubbery material.

Side note: I wouldn't at all trust superglue to hold aluminum plates together under repeated impact. VHB tape would probably serve you a lot better.

I agree. Super glue does not work well with any flexing. I would use a mechanical fastener. But cutting the whole thing out of silicone rubber would allow for flexing of fingers. The design would need to consider what you are trying to move with the fingers. How much do you need them to flex??

Our redesign of the AM stars was intended to make the fingers stronger for our intake. This was for the flat frisbees. We experimented with several heights and positions until we found one that worked.

If you were using these with something that moved easier (balls) you could get away with more flexible fingers. The frisbees did not want to slide very well and caught on the thin plate we used in the front of the collector. We ended up using a thin polycarbonate sheet in front of the aluminum plate and that worked well for pick up

[marccenter]

Wow,
I just priced some 1/2 inch silicone rubber sheets 1 foot square and was shocked at the price ($50/ pc). The idea of cutting this material out using a water jet may be cost prohibitive. Does anyone have experience with water jet cutting the interlocking floor tiles (7/8 inch thick), 2 foot square, used as the VEX field or commonly found at Home Depot, Lowes, for kid playing fields? If this material worked, it may make sense to proceed down the water jet cutting path of the floor tile material directly.

[AdamHeard]

Originally Posted by marccenter

Wow,
I just priced some 1/2 inch silicone rubber sheets 1 foot square and was shocked at the price ($50/ pc). The idea of cutting this material out using a water jet may be cost prohibitive. Does anyone have experience with water jet cutting the interlocking floor tiles (7/8 inch thick), 2 foot square, used as the VEX field or commonly found at Home Depot, Lowes, for kid playing fields? If this material worked, it may make sense to proceed down the water jet cutting path of the floor tile material directly.

Mcmaster pricing on a foot square is not the best way to price this. You'd want to get a larger sheet, from someone who sells rubber.

Cutting the starts from a 1' piece would nest poorly as well, wasting a lot more material than necessary.