254 telescoping arm design choices?

[smart1]

I recently started a thread regarding the 233 arms, 254's arm was discussed in that thread as well but I think it deserved another thread for my further questions. I am curious to know what type of belt 254 used this year and why they chose it. I have been trying to cad my own version to use for game piece manipulation. like 233 used theirs in '07,'08 and '11. And I'm also interested what the rollers are made of. Thanks

[1683cadder]

Have they posted a CAD of their design? I would really like to see it too

[smart1]

I do not believe so, that would be cool.

[bkahl]

I believe Cory McBride is the man to talk to here.

[MichaelBick]

Originally Posted by 1683cadder

Have they posted a CAD of their design? I would really like to see it too

While 254 did not post a CAD of their design, I was able to get extensive pictures of their robot at championships this year:

https://drive.google.com/folderview?...&usp=sha ring

[ohrly?]

Originally Posted by MichaelBick

While 254 did not post a CAD of their design, I was able to get extensive pictures of their robot at championships this year:

https://drive.google.com/folderview?...&usp=sha ring

I remember seeing some great photos of the elevators here, but I think the link must have since broken. Does anyone know of an updated link or mirror? Thank you so much!

[MichaelBick]

Originally Posted by MichaelBick

Stuff got moved around in my google drive, and the previous album link now does not work. I got a PM to repost the link so here it is: https://drive.google.com/folderview?...&usp=sha ring

I will have to try to find a more permanent solution for the future.

I reposted a link in the other thread but forgot to update it here.

[Travis Covington]

Originally Posted by smart1

I am curious to know what type of belt 254 used this year and why they chose it. I'm also interested what the rollers are made of. Thanks

The belt is a GT2 5mm pitch x 15mm wide gates timing belt. We used it because it was the smallest available size to allow for a moderate Factor of Safety for one arm to lift the entire robot.

The rollers are simply sleeve bushings (SAE 841 oil impregnated bronze) on an aluminum shaft. We wanted to use delrin rollers on the shafts, but had no desire to machine them ourselves. The bronze rollers were not ideal, but they worked fine.

Hope this helps.

[smart1]

Originally Posted by Travis Covington

The belt is a GT2 5mm pitch x 15mm wide gates timing belt. We used it because it was the smallest available size to allow for a moderate Factor of Safety for one arm to lift the entire robot.

The rollers are simply sleeve bushings (SAE 841 oil impregnated bronze) on an aluminum shaft. We wanted to use delrin rollers on the shafts, but had no desire to machine them ourselves. The bronze rollers were not ideal, but they worked fine.

Hope this helps.

Thanks, are there any changes you would make?

[Travis Covington]

Originally Posted by smart1

Thanks, are there any changes you would make?

The belt attachment method for the retracting motion wasn't optimal, but the overall packaging constraints made it hard to do much else. Ideally everything was a bit bigger to make design, assembly and maintenance easier. It was a pretty frustrating thing to work on. I think we only had a few students and mentors who knew how to fully assemble it and repair it.

[ohrly?]

Sorry to resurrect this thread, but any chance you could tell me what you used to keep the inner arms laterally centered? Is it the white things in this photo (https://docs.google.com/file/d/0B_WD...Y0U/edit?pli=1)? If so, what material is that?

[Cory]

Originally Posted by ohrly?

Sorry to resurrect this thread, but any chance you could tell me what you used to keep the inner arms laterally centered? Is it the white things in this photo (https://docs.google.com/file/d/0B_WD...U/edit?pli=1)? If so, what material is that?

Yes-they are teflon.