Go to Post Remember, WWGD? (What would Grandma Do?) - Vikesrock [more]
Home
Go Back   Chief Delphi > FIRST > General Forum
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
Thread Tools Rate Thread Display Modes
  #16   Spotlight this post!  
Unread 13-01-2013, 21:16
WileyB-J's Avatar
WileyB-J WileyB-J is offline
4976 Georgetown Rebels
FRC #4976 (Rebels)
Team Role: Mentor
 
Join Date: Feb 2011
Rookie Year: 2008
Location: Burlington, ON
Posts: 97
WileyB-J will become famous soon enoughWileyB-J will become famous soon enough
Re: ideas for a strong hook

Quote:
Originally Posted by Phyrxes View Post
Carabiners are traditionally rated in kN (approximately 225 lbs). The ratings are specific along the different parts of the carabiner, if you are going this route talk to your local outdoor store and see what they have.
Most carabiners are rated to 23kN, which is close to 5000 lbf. I warn, if you compromise the alloy structure of the 'beaner you significantly reduce its integrity, thus its holding strength. So if a team is going to use (aluminum) climbing 'beaners you need to design a coupling device that does not drill, cut or otherwise damage the unit. Steel ones are another story.
Reply With Quote
  #17   Spotlight this post!  
Unread 14-01-2013, 11:07
s1900ahon s1900ahon is offline
Registered User
AKA: Scott McMahon
FRC #2468 (Appreciate)
Team Role: Mentor
 
Join Date: May 2008
Rookie Year: 2008
Location: Austin, TX
Posts: 156
s1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant futures1900ahon has a brilliant future
Re: ideas for a strong hook

For Breakaway, our team fabricated a hook out of carbon fiber. It wasn't used in competition, as we followed our normal path of late mechanical construction and the winch mechanism was never integrated on the robot. It continues to be the object of strength testing to this day.

It was moderately simple to make (compared to the rest of the Breakaway robot that also used significant CF components). The mold was made by gluing+screwing a couple of 2x4 pieces together, and cutting out the hook shape on the bandsaw. After sanding and sealing with epoxy, we polished and waxed the surface, and then used PVA for a mold release. The hook layup was done with a wet process: 3 layers of 3K 2x2 twill CF, one layer of segmented 0.25" Nomex honeycomb, and 3 more layers of CF. Wrapped in a vacuum bag and left overnight. The whole thing took about 4 days in total to fabricate (3 for the mold making, and 1 for the layup).

Having described this, I believe the team will use a conventional, non-locking hook this year fabricated from aluminum. CF is a fun material to work with, but you have to be particularly careful of post-layup machining as the dust becomes hazardous.
Reply With Quote
  #18   Spotlight this post!  
Unread 14-01-2013, 11:34
ferret_guy ferret_guy is offline
Registered User
AKA: Mark Omo
FRC #1703 (RATS)
Team Role: Leadership
 
Join Date: Mar 2012
Rookie Year: 2008
Location: Henderson
Posts: 97
ferret_guy is on a distinguished road
Re: ideas for a strong hook

Quote:
Originally Posted by Phyrxes View Post
Carabiners are traditionally rated in kN (approximately 225 lbs). The ratings are specific along the different parts of the carabiner, if you are going this route talk to your local outdoor store and see what they have.
I am an avid rock limber and when the gate is removed the holding force along the long axis drops considerably usually from around 25kN to around 7kN it should be stamped right on there though but 7kN is still far more than you would ever need (about 1500lbs-force)
Reply With Quote
  #19   Spotlight this post!  
Unread 30-01-2013, 22:20
Trish Fisher Trish Fisher is offline
Registered User
FRC #2240 (Brute Force)
 
Join Date: Oct 2011
Rookie Year: 2012
Location: Denver, Colorado
Posts: 15
Trish Fisher is an unknown quantity at this point
Re: ideas for a strong hook

Quote:
Originally Posted by Greg McKaskle View Post
Repurposing some C-clamps might be a reasonable approach. Particularly ones similar to this http://www.sweetwater.com/store/detail/CClamp

Or use them as inspiration for building your own.

Greg McKaskle
Everyone, thank you for your hook suggestions! We used the one posted by Greg. The sweetwater clamp works perfectly! We used two of them on top of our ascent mechanism.

Thanks again to everyone!

Trish
Reply With Quote
  #20   Spotlight this post!  
Unread 30-01-2013, 23:30
G Fawkes G Fawkes is offline
Registered User
FRC #1290
Team Role: Mentor
 
Join Date: Mar 2012
Rookie Year: 2010
Location: Chandler, AZ
Posts: 28
G Fawkes is an unknown quantity at this point
Re: ideas for a strong hook

Quote:
Originally Posted by Trish Fisher View Post
Everyone, thank you for your hook suggestions! We used the one posted by Greg. The sweetwater clamp works perfectly! We used two of them on top of our ascent mechanism.
What is the thread diameter and pitch on the lower threaded hole? Would be sweet if it threaded straight onto a Bimba.
__________________
Si Se Puede
Reply With Quote
Reply


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 22:47.

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