Go to Post Scoring ringers is going to be like dating. While a select few will master it with relative ease, the vast majority will need quite a bit of time to refine their skills to an acceptable level. - artdutra04 [more]
Home
Go Back   Chief Delphi > Technical > Motors
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 24-05-2011, 13:16
steelerborn's Avatar
steelerborn steelerborn is offline
Engineer at JBT FoodTech
AKA: Jonathan Stokes
FRC #5817 (Uni-Rex)
Team Role: Mentor
 
Join Date: Jan 2009
Rookie Year: 2007
Location: Clovis
Posts: 288
steelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant future
shaft couplers

Just wondering what teams have used this method for quick transmission swaps at comp. The team that I mentor had a huge transmission failure going into the elimination rounds, and I thought that this would have saved the day for them. I brought this up to the CAD team and they loved the idea and will be implementing it hopefully in an offseason project. I would really love any thoughts from teams that have used the set-up.

Thanks

Here is a link for the part:
http://www.mcmaster.com/#shaft-couplers/=cg27rd
__________________
Good enough is the enemy of anything great!

team 1671
  #2   Spotlight this post!  
Unread 24-05-2011, 13:20
AdamHeard's Avatar
AdamHeard AdamHeard is offline
Lead Mentor
FRC #0973 (Greybots)
Team Role: Mentor
 
Join Date: Oct 2004
Rookie Year: 2004
Location: Atascadero
Posts: 5,526
AdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond reputeAdamHeard has a reputation beyond repute
Send a message via AIM to AdamHeard
Re: shaft couplers

Quote:
Originally Posted by steelerborn View Post
Just wondering what teams have used this method for quick transmission swaps at comp. The team that I mentor had a huge transmission failure going into the elimination rounds, and I thought that this would have saved the day for them. I brought this up to the CAD team and they loved the idea and will be implementing it hopefully in an offseason project. I would really love any thoughts from teams that have used the set-up.

Thanks

Here is a link for the part:
http://www.mcmaster.com/#shaft-couplers/=cg27rd
I know 973 used them as a coupling method to the metric output shaft of the KOP gearbox in 2005.

I'm not sure this quick change ability is that much of a benefit, what was the cause of their failure? If it's something likely to happen again I'd focus my efforts there instead.
  #3   Spotlight this post!  
Unread 24-05-2011, 13:37
kaliken kaliken is offline
294 Old Fart Mentor...
AKA: Ken S
FRC #0294 (Beach Cities Robotics)
Team Role: Mentor
 
Join Date: May 2010
Rookie Year: 2005
Location: Redondo Beach
Posts: 102
kaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant futurekaliken has a brilliant future
Re: shaft couplers

I can speak for my team that coupling a shaft could really help.

The couplers in your link we actually use to link our potentiometers to our shafts. We have both the rigid and semi flexible and they worked well.

I would be a bit worried about torque transmission if I was going to couple the output of a driving shaft so sizing the coupler would be essential.

In that respect, at championships we got hit with the infamous Banebot775 short in our lift gearbox. It wasn't pretty since this gearbox was tied to our lifter drum. Luckily we had a coupling device to connect the drum and gearbox instead of making it one big assembly. If it was a single assembly, it would have been major surgery to take the entire assembly out.

What we had was a home-made shaft coupler. The output shaft of the gearbox and the input side of the drum were both 0.5" hex. So we simply broached a hex into cylindrical stock and added a couple set screws. This allowed us to take the gearbox out, swap the motor and get back underway in minimal time. On top of that, we did a quick look at the torque and loads into the coupler and found it would be sufficient for what we needed to do.
__________________
2010 World Champions! Newton Alliance Captain: Many thanks to 67 and 177 for the amazing ride
  #4   Spotlight this post!  
Unread 24-05-2011, 13:51
steelerborn's Avatar
steelerborn steelerborn is offline
Engineer at JBT FoodTech
AKA: Jonathan Stokes
FRC #5817 (Uni-Rex)
Team Role: Mentor
 
Join Date: Jan 2009
Rookie Year: 2007
Location: Clovis
Posts: 288
steelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant futuresteelerborn has a brilliant future
Re: shaft couplers

It was with the Banebots motor, our encoder malfunctioned and caused the arm to continually raise till it hit the mechanical stop and just continued to drive since it did not know when to stop. The CAD team this year did a marvelous job and we had a plan in place. Obviously you cannot predict every negative scenario and this only happened once in all of our matches. So we want to have the ability that if the need arises, a quick swap would be beneficial. I am glad to see that it served its purpose kaliken. And if you are designing the bot in CAD it is not that difficult to add this system in. I am so proud of these kids they did all of the CAD and I only helped with fixing some mistakes that were made before they were sent to be manufactured. It never hurts to just have the option on the bot.
__________________
Good enough is the enemy of anything great!

team 1671
  #5   Spotlight this post!  
Unread 24-05-2011, 15:40
DonRotolo's Avatar
DonRotolo DonRotolo is offline
Back to humble
FRC #0832
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Atlanta GA
Posts: 7,019
DonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond repute
Re: shaft couplers

Just remember that the setscrew type don't transmit torque all that well, particularly rapidly changing torque. The split type are more reliable in that application.
__________________

I am N2IRZ - What's your callsign?
  #6   Spotlight this post!  
Unread 24-05-2011, 16:03
sanddrag sanddrag is offline
On to my 16th year in FRC
FRC #0696 (Circuit Breakers)
Team Role: Teacher
 
Join Date: Jul 2002
Rookie Year: 2002
Location: Glendale, CA
Posts: 8,519
sanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond repute
Re: shaft couplers

In 2007, shaft couplers were the cause of failure for 696 in two matches at the Los Angeles regional. They sat motionless on the field for two matches due to shaft coupler spiders getting torn up. I don't like them for FRC robots. They take up too much space.
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
  #7   Spotlight this post!  
Unread 24-05-2011, 22:28
pfreivald's Avatar
pfreivald pfreivald is offline
Registered User
AKA: Patrick Freivald
FRC #1551 (The Grapes of Wrath)
Team Role: Mentor
 
Join Date: Jan 2007
Rookie Year: 2001
Location: Naples, NY
Posts: 2,304
pfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond repute
Re: shaft couplers

Consider replacing set screws with cotter pins or spring pins.
__________________
Patrick Freivald -- Mentor
Team 1551
"The Grapes of Wrath"
Bausch & Lomb, PTC Corporation, and Naples High School

I write books, too!
  #8   Spotlight this post!  
Unread 26-05-2011, 06:25
Ninja_Bait's Avatar
Ninja_Bait Ninja_Bait is offline
Former Prez of Making Things Go
AKA: Jake Potter
FRC #0694 (StuyPulse)
Team Role: Alumni
 
Join Date: Apr 2010
Rookie Year: 2008
Location: New York
Posts: 650
Ninja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond reputeNinja_Bait has a reputation beyond repute
Re: shaft couplers

Cotter pins are the best. I made 694 use them so many times when set screws and keys failed.

On one of our old robots, there were some old gearboxes with threaded output shaft. They used tapped couplers to connect to smooth shaft. I thought that was really bizarre, but the tap + set screws made a really solid connection that was a total pain to remove.
__________________
You can't fix something that isn't broken... but you can always break things that aren't fixed!

  #9   Spotlight this post!  
Unread 26-05-2011, 09:08
Rob Stehlik's Avatar
Rob Stehlik Rob Stehlik is offline
Registered User
FRC #0610 (Coyotes)
Team Role: Engineer
 
Join Date: Sep 2009
Rookie Year: 2009
Location: Toronto
Posts: 101
Rob Stehlik is a glorious beacon of lightRob Stehlik is a glorious beacon of lightRob Stehlik is a glorious beacon of lightRob Stehlik is a glorious beacon of lightRob Stehlik is a glorious beacon of light
Re: shaft couplers

We have used shaft couplers in the past, and they work fine, but can be very bulky. I would recommend having the last stage of gear or chain reduction outside the transmission, so it is not directly coupled with whatever you are driving. This makes transmission swaps much easier.

On our arm, when one of the 775 motor started self destructing by spitting out fan blades (surprise!) we simply took off the chain, pulled the gearbox, and dropped in a replacement.

In our drive system, the gearbox has a gear on the output shaft that engages with a gear on one of the middle wheel shafts, which stays mounted in the frame permanently. So when the shifter pin broke, we were able to pull out the gearbox and swap it very quickly.

A lot of designs use an extra long shaft on the gearbox to direct drive a wheel, but this makes it a real pain to take the gearbox out.

Obviously designing for quick replacement is a nice thing to have, but as Adam said, it might be more beneficial to find out what caused the problem in the first place. In our case, I think the shifter pin broke because we didn't limit the stroke of the air cylinder properly.
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 15:06.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi