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-   -   What kind of cylinders does your team stock? (http://www.chiefdelphi.com/forums/showthread.php?t=131697)

ThunderPorpoise 24-12-2014 16:47

What kind of cylinders does your team stock?
 
I'm looking into purchasing some pneumatic cylinders for my team and I'm a bit swamped by how many options there are. What do your teams keep in stock for various tasks that you might need to accomplish? (In terms of Bore, Stroke, Double or Single Acting, etc.)

MrForbes 24-12-2014 17:32

Re: What kind of cylinders does your team stock?
 
We "stock" the leftovers from previous robots, and the ones we bought for previous robots that didn't work out quite right. We find we usually use 3/4" bore by 1, 2, 3, 4, 6, 8" stroke, and we have a pair of 1.5" bore x 8" stroke that have been used in a few different robots.

Mike Marandola 24-12-2014 17:39

Re: What kind of cylinders does your team stock?
 
We keep an assortment of double acting cylinders from 1/2" to 3" bore and 1/2" to about 12" stroke. We like to have at least two of each in case we need one on each side of a system. 225 gave us some small single acting cylinders at Midknight Mayhem so maybe we'll get a chance to use them this year. One thing that we need to work on is keeping clevises for all cylinder sizes in stock.

billbo911 24-12-2014 17:47

Re: What kind of cylinders does your team stock?
 
Quote:

Originally Posted by MrForbes (Post 1416780)
We "stock" the leftovers from previous robots, and the ones we bought for previous robots that didn't work out quite right. We find we usually use 3/4" bore by 1, 2, 3, 4, 6, 8" stroke, and we have a pair of 1.5" bore x 8" stroke that have been used in a few different robots.

This is as close to exactly what I was going to say that I don't need to change anything.

Chris is me 24-12-2014 19:27

Re: What kind of cylinders does your team stock?
 
Cylinders are really the kind of thing you order once you know your design, or at least know what you're prototyping. McMaster sells them so we can get them in a day or two, and for everything else we use cylinders from old robots. Generally always double acting, front and rear pivot mounting.

dradel 24-12-2014 21:22

Quote:

Originally Posted by MrForbes (Post 1416780)
We "stock" the leftovers from previous robots, and the ones we bought for previous robots that didn't work out quite right. We find we usually use 3/4" bore by 1, 2, 3, 4, 6, 8" stroke, and we have a pair of 1.5" bore x 8" stroke that have been used in a few different robots.


Curious here... It was my understanding that parts that are used on a bot cannot be reused on a later bot if it is modified. Technically speaking wouldn't putting fittings into an air cylinder make it no longer off the shelf?

The way it was explained to us lends itself to just that. Same holds true for transmissions and such ( hence why we haven't gone with two speed trans yet)

EricH 24-12-2014 21:30

Re: What kind of cylinders does your team stock?
 
Quote:

Originally Posted by dradel (Post 1416814)
Curious here... It was my understanding that parts that are used on a bot cannot be reused on a later bot if it is modified. Technically speaking wouldn't putting fittings into an air cylinder make it no longer off the shelf?

Technically... Yes. But the cylinder can be restored to COTS by removing those fittings. Takes 5 minutes or less. (OK, maybe plugging the output ports too.) And then you put the fittings back in.

You could also reference R16 from the 2014 rules, covering an edge case.

To answer the original question... 1197 has a couple of 2" bore, 24"+ throw cylinders laying around the shop (one in original packaging!), in addition to the usual 3/4" and 1.5" bores in various lengths. The big cylinders are primarily useful for "Hey, who wants a strong, slow, and heavy air-hogging mechanism?"

dradel 24-12-2014 21:41

So by your reasoning a team could reuse cylinders, transmissions, compressor, swerve drive and so on if they disassemble then reassemble ?

artdutra04 24-12-2014 21:47

Re: What kind of cylinders does your team stock?
 
Quote:

Originally Posted by dradel (Post 1416816)
So by your reasoning a team could reuse cylinders, transmissions, compressor, swerve drive and so on if they disassemble then reassemble ?

We won't know the 2015 rules for another week-ish, but under 2014 and prior rules anything restored to identical COTS condition is legal for reuse.

Chris is me 24-12-2014 22:04

Re: What kind of cylinders does your team stock?
 
Quote:

Originally Posted by dradel (Post 1416814)
Curious here... It was my understanding that parts that are used on a bot cannot be reused on a later bot if it is modified. Technically speaking wouldn't putting fittings into an air cylinder make it no longer off the shelf?

...And then when you take them back off, it returns to being a COTS item.

Quote:

Originally Posted by dradel (Post 1416816)
So by your reasoning a team could reuse cylinders, transmissions, compressor, swerve drive and so on if they disassemble then reassemble ?

If they are off the shelf items, with no modifications whatsoever, yes absolutely. Hundreds of teams reuse compressors every year.

If the swerve drive happens to be a bought product, and again if the parts are unmodified, it needs to be restored to an off-the-shelf state and then it can be reused.

Any custom made parts, any COTS parts modified by machining, anything you actually "made" cannot be reused. So this is why teams design and build new drive bases every year. But if both drive bases use Toughboxes, and they didn't add any mounting holes or otherwise change them, reusing is functionally identical to buying another. So to save teams money it's permitted to take those COTS Toughboxes and put them on a NEW custom drive base, for example.

Again, *any* modification (that isn't / can't be reversed) changes the part from COTS to a custom part and it cannot be reused.

All of this post assumes the 2015 rules are similar to the rules in 2014 and before.

dradel 24-12-2014 22:07

Thanks for the explanation !! Changes things dramatically for our team!!

Mr V 25-12-2014 00:12

Re: What kind of cylinders does your team stock?
 
Personally I can't see FIRST changing the rules regarding reusing COTS items, it would just place an unnecessary expense on teams. Especially this season with the fact that new motor controllers were introduced/approved so late and the potential for there being shortages of them.

AdamHeard 25-12-2014 00:59

Re: What kind of cylinders does your team stock?
 
Quote:

Originally Posted by Chris is me (Post 1416794)
Cylinders are really the kind of thing you order once you know your design, or at least know what you're prototyping. McMaster sells them so we can get them in a day or two, and for everything else we use cylinders from old robots. Generally always double acting, front and rear pivot mounting.

Agreed. We let mcmaster (and Automation direct) stock them for us!

Dave Campbell 26-12-2014 14:15

Re: What kind of cylinders does your team stock?
 
Feeling a bit spoiled as our main team sponsor is Clippard Instruments.... we stock every COTS cylinders, fittings, valves and tubing in their catalog. In addition, they hire students from my program and our team members to work for the company, custom making many parts for our machine....check them out here: Clippard

Yes, they are the same company that donate the Volume Storage Tanks to all FRC teams.
A true FIRST partnership in action!

Oblarg 26-12-2014 15:30

Re: What kind of cylinders does your team stock?
 
Quote:

Originally Posted by Mike Marandola (Post 1416781)
We keep an assortment of double acting cylinders from 1/2" to 3" bore and 1/2" to about 12" stroke. We like to have at least two of each in case we need one on each side of a system. 225 gave us some small single acting cylinders at Midknight Mayhem so maybe we'll get a chance to use them this year. One thing that we need to work on is keeping clevises for all cylinder sizes in stock.

This.

You get three bimba cylinders every year in the KOP, so it doesn't take all that long to build up a collection. Clevises and pivot brackets, on the other hand, are a perennial issue.

A tip: Use a vise to knock out the pin that comes in the rear-pivot assembly of the bimba cylinders, and use a bolt instead. It's far more convenient.


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