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Unread 01-30-2010, 09:16 AM
BOSS BOSS is offline
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Pneumatics cv.32

We are looking at ways to speed up our Kicker. We are able to use a Mack valve to propel our ball at great speeds but when we go down to the 1/8th inch NPT and a cv of .32 we believe we will not get the same speed. What ways can we speed this up we are looking at using 3 valves together perhaps.
Also can we buy other valves as long as they meet the .32 cv and the 1/8th inch npt. We are looking at a closed center valve solenoid to help with air and pressure for lifters can we do that as well.

What do you think?
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Unread 01-30-2010, 09:30 AM
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Re: Pneumatics cv.32

Be warned: I would expect the GDC to realize that they have made a typographical error in the rules and will require 1/8" NPT fittings on the cylinder and prohibit larger than .160 ID tubing...

Until then (assuming you have 1/4" NPT fittings on your cylinder), ganging 4 solenoids in parallel should give you 4 times the air flow. After that, additional solenoids give you diminishing returns.

Regards,

Mike
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As easy as 355/113...

Last edited by Mike Betts : 01-30-2010 at 09:35 AM.
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Unread 01-30-2010, 10:39 AM
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Re: Pneumatics cv.32

Quote:
Originally Posted by Mike Betts View Post
Be warned: I would expect the GDC to realize that they have made a typographical error in the rules and will require 1/8" NPT fittings on the cylinder and prohibit larger than .160 ID tubing...
Mike,

Don't the rules already prohibit larger than .160 ID tubing ?


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Unread 01-30-2010, 05:53 PM
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Mike Betts Mike Betts is offline
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Re: Pneumatics cv.32

Quote:
Originally Posted by Ether View Post
Mike,

Don't the rules already prohibit larger than .160 ID tubing ?


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Mike Betts

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As easy as 355/113...
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Unread 01-30-2010, 06:03 PM
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Re: Pneumatics cv.32

Quote:
Originally Posted by Mike Betts View Post
Show me... I've been wrong before...
<R71> plus <R72>E ?

<R71> To satisfy multiple constraints associated with safety, consistency, robot inspection, and constructive innovation, no pneumatic parts other than those explicitly permitted by the Pneumatic System Rules may be used on the ROBOT.

<R72> In addition to the items included in the KOP, pneumatic system items specifically permitted on 2010 FRC ROBOTS include the following items. All included items must be “off the shelf” pneumatic devices rated by their manufacturers for pressure of at least 125psi, and used in their original, unaltered condition (except as required for assembly with other components).

E. Additional 0.160” inch inside diameter pneumatic tubing functionally equivalent to that provided in the KOP, with the pressure rating clearly factory-printed on the exterior of the tubing (note: alternate tubing colors are acceptable).


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Unread 01-30-2010, 06:15 PM
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Re: Pneumatics cv.32

If you read my original post, I stated that I thought that the GDC would have to correct this oversight.

As the rules read right now, I am permitted to use .160 ID, I do not have to...

I really don't want to lawyer this. IMHO, the intent is to limit air flow and the GDC will have to amend the rules to enforce it...

I would suggest that you have your Main Team Contact ask via the official Q&A. As a mere lead inspector, I do not have the authority to do so...

Regards,

Mike
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As easy as 355/113...
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Unread 01-30-2010, 06:34 PM
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Re: Pneumatics cv.32

Quote:
Originally Posted by BOSS View Post
We are looking at ways to speed up our Kicker. We are able to use a Mack valve to propel our ball at great speeds but when we go down to the 1/8th inch NPT and a cv of .32 we believe we will not get the same speed. What ways can we speed this up
...
What do you think?

There are many possible design approaches which avoid the dreaded 1/8" 0.32Cv "pneumatic damper" problem. Just a few are:

1) Use a piston to push a heavily spring-loaded (or surgical-tube-loaded) kicker into armed and latched position, then retract the piston out of the way before releasing the latch to fire.

2) Use lightly loaded surgical tubing (or spring) to return the kicker to latched position, then arm by pre-charging a large bore cylinder with a vented front end*. Release the latch to fire. Once fired, vent the charge to allow the surgical tubing to pull the kicker back into latched position. Re-charge and repeat.

3) Connect lightly-loaded surgical tubing to the kicker in such a direction that it pulls the kicker back into the latched position. Attach doubled-up (tripled up?) surgical tubing between a piston and the kicker in such a direction that retracting the piston pulls the kicker forward via the tubing. With the piston extended, the lightly loaded tubing pulls the kicker back into latched position. Once latched, pull the piston back pneumatically to stretch the doubled-up tubing to arm the kicker. Release the latch to fire. Extend the piston to return the kicker to latched position and repeat.


Notes:

method#2 assumes it is legal to leave the cylinder vented (http://forums.usfirst.org/showthread.php?t=14218);
...the other two methods avoid this question altogether

method#2 and #3 have the added benefit that the kicker can be stored in the retracted and latched position (no concerns about extending beyond frame perimeter) without any potentially unsafe stored energy, and without the need for extra locking hardware. This should please the inspectors.


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Last edited by Ether : 01-31-2010 at 08:43 AM. Reason: 1) added note 2) grammar 3) clarification 4) added link
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Unread 01-30-2010, 06:48 PM
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Re: Pneumatics cv.32

Hi Mike,


Quote:
Originally Posted by Mike Betts View Post
If you read my original post, I stated that I thought that the GDC would have to correct this oversight.
I read your original post, and I understood your statement. I disagree with your statement. Explanation follows.


Quote:
As the rules read right now, I am permitted to use .160 ID, I do not have to...
To me, the rules are clear that .160 is required, because of Rule<R71>:

no pneumatic parts other than those explicitly permitted by the Pneumatic System Rules may be used on the ROBOT

Quote:
I really don't want to lawyer this.
Neither do I.

Quote:
IMHO, the intent is to limit air flow
Agree!!

Quote:
and the GDC will have to amend the rules to enforce it...
disagree.

Quote:
I would suggest that you have your Main Team Contact ask via the official Q&A.
We don't need to. We plan to follow Rule <R71> and use only the explicitly permitted pneumatic parts.


Quote:
As a mere lead inspector, I do not have the authority to do so...
Thanks for the time and effort you put into being an inspector. It is appreciated.

Grace,

Ether

Last edited by Ether : 01-30-2010 at 11:46 PM.
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Unread 01-30-2010, 09:14 PM
BOSS BOSS is offline
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Re: Pneumatics cv.32

I am glad to see that you both got to vent over the rules. As can be seen by both of your posts, I need to stick with whats given to me, so I ll use the hoses given to me, Ill use the solenoid given to just add 2 or 3 to it as long as they meet 125 psi. I am thinking it does not matter as long as I purchase them over the counter and they hold 125 psi I believe I can increase my air flow in this manner and not use springs or surgical tubing. But I could be wrong. Thanks I hope you enjoyed this as much as I enjoyed reading it.
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Unread 01-30-2010, 11:12 PM
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Re: Pneumatics cv.32

Quote:
Originally Posted by BOSS View Post
I believe I can increase my air flow in this manner and not use springs or surgical tubing. But I could be wrong.
Let us know how it turns out please?

I'm not placing any bets but my guess is you won't see dramatic improvement (if you stick to the 0.160 ID tubing)

Take a look at this post for other possible ideas:
http://www.chiefdelphi.com/forums/showpost.php?p=910176


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