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-   -   Looking for slip rings and distributors (http://www.chiefdelphi.com/forums/showthread.php?t=130622)

sanelss 23-09-2014 02:27
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by asid61 (Post 1401132)
Link to source? I have been looking for legality stuff on slip rings for a while, but I couldn't find anything on the Q&A or in the official rules, other than that custom circuits are prohibited.

Also, bomb squad uses the Mercotac Model 230 slip ring according to a PM I got a while back. They're ~$100 each online it looks like.
aren't those illegal then?. the 230 is only 2 channels at 30 amps per channel and doesn't meet the proper rated requirements of 40 amps?

sanelss 23-09-2014 02:30
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by asid61 (Post 1401135)
Like, able to rotate freely without the cim. Essentially, outsource all wires to areas outside the rotating module.

well our design not only has a cim rotating with it but also a servo(we are doing a 2 speed shifting swerve, or at least attempting to) so we need some kind of slip ring with 5 channels 2 of which needs to be 40A for the cim. i mean we could just stick wires through the center as people have pointed out but we don't want to have to deal with all the issues related to untangling the wires.

Aren Siekmeier 23-09-2014 02:57
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by sanelss (Post 1401137)
well our design not only has a cim rotating with it but also a servo(we are doing a 2 speed shifting swerve, or at least attempting to) so we need some kind of slip ring with 5 channels 2 of which needs to be 40A for the cim. i mean we could just stick wires through the center as people have pointed out but we don't want to have to deal with all the issues related to untangling the wires.
You can also find through-bore slip rings that would allow you to combine multiple different slip rings with a wide variety of specs. For example these guys.

Some suppliers can also build custom slip rings for you, but you'd have to be careful about the legality of these during the season.

Dunngeon 23-09-2014 03:11
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by sanelss (Post 1401137)
well our design not only has a cim rotating with it but also a servo(we are doing a 2 speed shifting swerve, or at least attempting to) so we need some kind of slip ring with 5 channels 2 of which needs to be 40A for the cim. i mean we could just stick wires through the center as people have pointed out but we don't want to have to deal with all the issues related to untangling the wires.
If you look at Pwnage's CIM in wheel swerve ( I think), they have a piece of code that, depending on how far the swerve module has rotated (with three complete rotations in one direction being the max IIRC) automatically turns the wheel the opposite direction to compensate for rotation of the wires. It's a fairly simple fix, and they said it had a minimal impact on reaction speed of the robot.

This would remove the need for slip-rings, which would bring the overall cost of the modules down quite a lot while simplifying construction.

Also, if you don't mind me asking, exactly how are you planning on packaging this swerve module?

sanelss 23-09-2014 03:25
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by compwiztobe (Post 1401138)
You can also find through-bore slip rings that would allow you to combine multiple different slip rings with a wide variety of specs. For example these guys.

Some suppliers can also build custom slip rings for you, but you'd have to be careful about the legality of these during the season.
thanks. i've found a few potential suppliers but none of them have prices and who knows what kind of lead time is required. sourcing these $@#$@#$@#$@# things is no easy task =\

sanelss 23-09-2014 03:28
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by Dunngeon (Post 1401139)
If you look at Pwnage's CIM in wheel swerve ( I think), they have a piece of code that, depending on how far the swerve module has rotated (with three complete rotations in one direction being the max IIRC) automatically turns the wheel the opposite direction to compensate for rotation of the wires. It's a fairly simple fix, and they said it had a minimal impact on reaction speed of the robot.

This would remove the need for slip-rings, which would bring the overall cost of the modules down quite a lot while simplifying construction.

Also, if you don't mind me asking, exactly how are you planning on packaging this swerve module?
We've done a system like that before and we know it is doable we would just rather avoid it hence why we are trying this approach. it certainly is going to cost more but we want to try this during the off seasons to see if we can perfect it by competition time or go with another system(like the one you mentioned)

not sure what you mean in regards to packaging it, elaborate? As in the over all structure of it or???

Al Skierkiewicz 23-09-2014 08:18
Re: Looking for slip rings and distributors
 
Everyone,
The Mercotac slip rings are not slip rings in the true sense of the word. They are mercury filled contacts and are not legal on FRC robots. If you read the application notes on these contacts, you will see warnings about mercury leakage when mechanically stressed or when max current is exceeded. I contacted the manufacturer and was told that those events are rare but do occur. Mercury spills on an FRC field will close down the event.

cgmv123 23-09-2014 10:44
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by asid61 (Post 1401132)
Link to source? I have been looking for legality stuff on slip rings for a while, but I couldn't find anything on the Q&A or in the official rules, other than that custom circuits are prohibited.
2014 R48. Obligatory rules may change next year disclaimer.

nathannfm 23-09-2014 10:58
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by asid61 (Post 1401132)
bomb squad uses the Mercotac Model 230 slip ring according to a PM I got
Quote:
Originally Posted by Al Skierkiewicz (Post 1401146)
Everyone,
The Mercotac slip rings are not slip rings in the true sense of the word. They are mercury filled contacts and are not legal on FRC robots. If you read the application notes on these contacts, you will see warnings about mercury leakage when mechanically stressed or when max current is exceeded. I contacted the manufacturer and was told that those events are rare but do occur. Mercury spills on an FRC field will close down the event.
Ummmm...

JVN 23-09-2014 11:13
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by Al Skierkiewicz (Post 1401146)
Everyone,
The Mercotac slip rings are not slip rings in the true sense of the word. They are mercury filled contacts and are not legal on FRC robots. If you read the application notes on these contacts, you will see warnings about mercury leakage when mechanically stressed or when max current is exceeded. I contacted the manufacturer and was told that those events are rare but do occur. Mercury spills on an FRC field will close down the event.
Which rule is this illegal based on? Looks like <R8>?
What is the definition of hazardous?
Is there a list of hazardous materials? Mercury isn't mentioned in the blue box next to this rule.

If there is no list, does that mean it is up to the individual inspector to judge the hazardous nature of the material?

As such... isn't the legality of this sort of component determined by the lead-inspector at an event?

Al Skierkiewicz 23-09-2014 11:24
Re: Looking for slip rings and distributors
 
John,
Not sure what to answer here...
Does mercury need to be on a hazardous materials list?

Joe Ross 23-09-2014 11:24
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by Al Skierkiewicz (Post 1401146)
Everyone,
The Mercotac slip rings are not slip rings in the true sense of the word. They are mercury filled contacts and are not legal on FRC robots. If you read the application notes on these contacts, you will see warnings about mercury leakage when mechanically stressed or when max current is exceeded. I contacted the manufacturer and was told that those events are rare but do occur. Mercury spills on an FRC field will close down the event.
Per Q/A, they were legal in 2006, 2009, and 2011, and illegal in 2010. The reason for them being illegal in 2010 was not because of mercury, but because any type of slip ring was not legal in 2010. There have been no relevant Q/As since 2011.

Karthik 23-09-2014 11:50
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by Al Skierkiewicz (Post 1401146)
Everyone,
The Mercotac slip rings are not slip rings in the true sense of the word. They are mercury filled contacts and are not legal on FRC robots. If you read the application notes on these contacts, you will see warnings about mercury leakage when mechanically stressed or when max current is exceeded. I contacted the manufacturer and was told that those events are rare but do occur. Mercury spills on an FRC field will close down the event.
Quote:
Originally Posted by JVN (Post 1401169)
Which rule is this illegal based on? Looks like <R8>?
What is the definition of hazardous?
Is there a list of hazardous materials? Mercury isn't mentioned in the blue box next to this rule.

If there is no list, does that mean it is up to the individual inspector to judge the hazardous nature of the material?

As such... isn't the legality of this sort of component determined by the lead-inspector at an event?
Quote:
Originally Posted by Joe Ross (Post 1401173)
Per Q/A, they were legal in 2006, 2009, and 2011, and illegal in 2010. The reason for them being illegal in 2010 was not because of mercury, but because any type of slip ring was not legal in 2010. There have been no relevant Q/As since 2011.
I'm now slightly confused. Were these slip rings legal or illegal in 2014?

Kevin Ainsworth 23-09-2014 14:23
Re: Looking for slip rings and distributors
 
Search "2451 PWNAGE Off-season 2012" for a custom slip ring. This design is not currently legal due to the COTS rule unless the brush assembly is considered COTS since it is the slip ring itself. We have asked First to consider allowing custom "mechanical" slip rings. Let the kids explore the possibilities. Our prototype uses the brush assembly out of a CIM motor and we double up the brushes for each motor wire so this will be more than adequate for powering a CIM. Bag motor brush assemblies could be added to allow for sensors, etc. or possibly used instead of CIM units to bring the size down. We have done testing using these slip rings in the off season with great results. We have been playing around with the idea of rapid prototyping the housings and sharing the designs with the First community if they would be allowed for future seasons. We have also shared our design with Andy Baker and spoken with individuals at Vex.

Al Skierkiewicz 23-09-2014 14:28
Re: Looking for slip rings and distributors
 
Joe,
As far as I know, mercury contacts have never been legal on FRC robots even when slip rings were allowed due the the hazards.


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