Go to Post I'm not worried about talking to the robot, but I am worried about when the robot starts talking back... - Moros [more]
Home
Go Back   Chief Delphi > Technical > Technical Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
 
 
Thread Tools Rate Thread Display Modes
Prev Previous Post   Next Post Next
  #15   Spotlight this post!  
Unread 29-10-2011, 19:12
Tom Line's Avatar
Tom Line Tom Line is offline
Raptors can't turn doorknobs.
FRC #1718 (The Fighting Pi)
Team Role: Mentor
 
Join Date: Jan 2007
Rookie Year: 1999
Location: Armada, Michigan
Posts: 2,541
Tom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond repute
Re: High Tensile Sprocket Bolts

Fun times. Our 2010 soccer bot was 8 wheel drive. The AM sprockets were small enough that we had to use spacers for the chain to clear the wheel hub.

We have sheared off close to 50 bolts. Grade 8, partial thread. We know they are tight, because we were tightening them so MUCH that we started bending the sprockets and compressing the plastic of the plaction wheel.

Simply put, the combination of AM sprockets, with AM spacers, on AM plaction wheels, can't hold up over time. The 10-32 bolts will sheer every time if you're putting serious loading on them. This is on a 4 inch wheel with 24(ish) teeth on the sprocket. 2 cims per side, run through tough boxes. A 3:2 sprocket ratio from the tough box to wheels.

AM could address this by putting locking indentations on both the plaction and the sprocket, and then putting bumps on the spacer so that when the three are clamped together, the bumps/buttons take the shear.

Bolts stink in shear. Tension is their game.

This year, we went with bigger sprockets so that we could get rid of the AM spacers. We never sheared a single bolt. Lesson learned.

Last edited by Tom Line : 29-10-2011 at 19:15.
 


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 07:37.

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