You can spoil my row any time.
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
  #31   Spotlight this post!  
Unread 12-12-2011, 16:34
Ninja_Bait's Avatar
Happy Birthday! 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: Tips on loosing weight (Not spam)

Quote:
Originally Posted by Chris is me View Post
I've only used stuff in .25 inch wall thickness - much better results that way for rigidity but lightening is recommended.w
I liked the two-hockey-stick arms, too (practically solid fiberglass) but our arm was just a disaster in general. It was too long, too thin, and too holey. I plan to stick with thin-walled aluminum and wise design for this year to avoid any possibility of composite catastrophe.
__________________
You can't fix something that isn't broken... but you can always break things that aren't fixed!

Reply With Quote
  #32   Spotlight this post!  
Unread 12-12-2011, 16:44
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: 5,529
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: Tips on loosing weight (Not spam)

I love thin wall aluminum.

I don't want to tell teams to not use composites, but most of the time I see them used "in place" of aluminum they are used in much more volume so their lower density provides no weight advantage, and a thin-wall aluminum member would be more efficient.

I see them used right time to time, and it makes me happy every time to see something different used effectively; but that unfortunately seems to be the minority.
Reply With Quote
  #33   Spotlight this post!  
Unread 12-12-2011, 19:14
roystur44's Avatar
roystur44 roystur44 is offline
Mentor/Sponsor
AKA: Roy Dumlao
FRC #4543 (Apollo Robotics)
Team Role: Mentor
 
Join Date: Mar 2010
Rookie Year: 2006
Location: San Jose,California
Posts: 363
roystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond reputeroystur44 has a reputation beyond repute
Send a message via Yahoo to roystur44
Re: Tips on loosing weight (Not spam)

[quote=AdamHeard;1090563]I love thin wall aluminum.

I'm surprised I haven't seen a team make a round tubular frame similiar to a bike frame or go cart frame.

If you guys have never seen a tube laser cut tube check it out on youtube

Roy
__________________
Roy Dumlao

Mentor/Sponsor
2006-2012 971
2013-2017 4543
Reply With Quote
  #34   Spotlight this post!  
Unread 12-12-2011, 19:44
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: 5,529
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: Tips on loosing weight (Not spam)

[quote=roystur44;1090601]
Quote:
Originally Posted by AdamHeard View Post
I love thin wall aluminum.

I'm surprised I haven't seen a team make a round tubular frame similiar to a bike frame or go cart frame.

If you guys have never seen a tube laser cut tube check it out on youtube

Roy
It's more difficult to work with when compared with other methods.

67 is about as close as I've seen.
Reply With Quote
  #35   Spotlight this post!  
Unread 12-12-2011, 19:57
BJC's Avatar
BJC BJC is offline
Simplicity is Complicated!
AKA: Bryan Culver
FRC #0033 (The Killer Bees)
Team Role: Alumni
 
Join Date: Jan 2010
Rookie Year: 2009
Location: Kettering/Greenville
Posts: 708
BJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

67 and 469 routinely make the top half of their robots out of thinwall aluminum tubing. It is VERY light, thin, and strong stuff. Instead of using 1/16 box on an arm, .0200 aluminum tubing could provide a lighter alternative. The warning that comes with this is that you need to make sure you properly design so it is not loaded in the wrong direction. Our entire 2007 double jointed arm was made out of this and it weighed maybe 5lbs max.
__________________
robot robot robot? Robot. Robot? Robot!
-----------------Team 33------------------

Last edited by BJC : 12-12-2011 at 20:42. Reason: off by a decimal point
Reply With Quote
  #36   Spotlight this post!  
Unread 12-12-2011, 20:21
JamesCH95's Avatar
JamesCH95 JamesCH95 is offline
Hardcore Dork
AKA: JCH
FRC #0095 (The Grasshoppers)
Team Role: Engineer
 
Join Date: Dec 2004
Rookie Year: 2001
Location: Enfield, NH
Posts: 1,904
JamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

Our arm this year was around 0.065 or 0.050 1.5"OD tube, worked great.
__________________
Theory is a nice place, I'd like to go there one day, I hear everything works there.

Maturity is knowing you were an idiot, common sense is trying to not be an idiot, wisdom is knowing that you will still be an idiot.
Reply With Quote
  #37   Spotlight this post!  
Unread 12-12-2011, 20:31
ratdude747's Avatar
ratdude747 ratdude747 is offline
Official Scorekeeper
AKA: Larry Bolan
no team
 
Join Date: Feb 2009
Rookie Year: 2008
Location: Madison, IN
Posts: 1,065
ratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond reputeratdude747 has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

1024 uses thin wall tubing a lot as well... they have access to a good tube bender, so that's what gets used and, IMHO, used well.
__________________
Dean's List Semi-finalist 2010
1747 Harrison Boiler Robotics 2008-2010, 2783 Engineers of Tomorrow 2011, Event Volunteer 2012-current

DISCLAIMER: Any opinions/comments posted are solely my personal opinion and does not reflect the views/opinions of FIRST, IndianaFIRST, or any other organization.
Reply With Quote
  #38   Spotlight this post!  
Unread 12-12-2011, 20:41
apalrd's Avatar
apalrd apalrd is offline
More Torque!
AKA: Andrew Palardy (Most people call me Palardy)
VRC #3333
Team Role: College Student
 
Join Date: Mar 2009
Rookie Year: 2009
Location: Auburn Hills, MI
Posts: 1,347
apalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

Quote:
Originally Posted by BJC View Post
.200 aluminum tubing
You're off by a decimal point, about.

We've used .035 thinwall aluminum for very high stress applications (arm in 2007), it's just really hard to weld...

I believe 469 uses something around the same thickness, in various diameters, for basically everything, with rivets holding everything together. Very very lightweight.

We've used material as thin as .050 and .063 in drivetrains, back in the days before mandatory bumpers (we had no bumpers, they lived).


As to tubular frames, how about this:http://www.chiefdelphi.com/media/photos/12949 and http://www.chiefdelphi.com/media/photos/12952 (same robot) - Chief Delphi 2000
__________________
Kettering University - Computer Engineering
Kettering Motorsports
Williams International - Commercial Engines - Controls and Accessories
FRC 33 - The Killer Bees - 2009-2012 Student, 2013-2014 Advisor
VEX IQ 3333 - The Bumble Bees - 2014+ Mentor

"Sometimes, the elegant implementation is a function. Not a method. Not a class. Not a framework. Just a function." ~ John Carmack

Last edited by apalrd : 12-12-2011 at 20:42. Reason: Messed up one of the links
Reply With Quote
  #39   Spotlight this post!  
Unread 12-12-2011, 21:32
JamesCH95's Avatar
JamesCH95 JamesCH95 is offline
Hardcore Dork
AKA: JCH
FRC #0095 (The Grasshoppers)
Team Role: Engineer
 
Join Date: Dec 2004
Rookie Year: 2001
Location: Enfield, NH
Posts: 1,904
JamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond reputeJamesCH95 has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

Quote:
Originally Posted by apalrd View Post
You're off by a decimal point, about.

We've used .035 thinwall aluminum for very high stress applications (arm in 2007), it's just really hard to weld...

I believe 469 uses something around the same thickness, in various diameters, for basically everything, with rivets holding everything together. Very very lightweight.

We've used material as thin as .050 and .063 in drivetrains, back in the days before mandatory bumpers (we had no bumpers, they lived).


As to tubular frames, how about this:http://www.chiefdelphi.com/media/photos/12949 and http://www.chiefdelphi.com/media/photos/12952 (same robot) - Chief Delphi 2000
It just takes a patient welder

This is a weld I did in college, but one of my students two years ago was welding soda cans together like this for fun in her shop class. It is certainly non-trivial, but definitely doable.
__________________
Theory is a nice place, I'd like to go there one day, I hear everything works there.

Maturity is knowing you were an idiot, common sense is trying to not be an idiot, wisdom is knowing that you will still be an idiot.

Last edited by JamesCH95 : 12-12-2011 at 21:35.
Reply With Quote
  #40   Spotlight this post!  
Unread 12-12-2011, 22:58
Jeff Pahl's Avatar
Jeff Pahl Jeff Pahl is offline
likes to look at shiny things...
FRC #5148 (New Berlin Blitz)
Team Role: Engineer
 
Join Date: Oct 2004
Rookie Year: 2004
Location: Waukesha, WI
Posts: 344
Jeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond reputeJeff Pahl has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

Quote:
Originally Posted by eagle33199 View Post
The biggest way to lose weight... Ask the inspector to take his foot off the scale
Quote:
Originally Posted by Al Skierkiewicz View Post
Cmon! Jeff and I only did that to you once! OK maybe twice but that was all I swear!
Al, it may have happened once or twice when you weren't around

On a serious note:

Weight management is a subject that is very near and dear to my heart after spending 15 years building spaceflight hardware. When the contracts include penalties that run on the order of $60/gram for being above the spec limit, you learn to pay a lot of attention to weight.

The first thing I tell rookie teams in any of my presentations is to buy a decent scale. It's an investment, just like any other tool. One I like is this one from Grainger. It's just over $200, has a 400 lb capacity, and has a remote display so you don't have to try and get your head under the robot. The extra capacity means you can set a plywood platform on it so the robot will fit, or that you can weigh your crate before you ship to Championship after your well designed under-weight robot wins your regional If you really can't afford to buy a scale, try the one the wrestling team uses. Or find a local company (sponsor) that will let you use their shipping scale a few times. Buy a small scale and weigh all the parts of your robot. There really is no excuse for showing up at the competition being 10's of pounds overweight.

The rest of the secrets have been mentioned several times in this thread already:

1) Make a weight budget.

2) Enforce the weight budget.

3) See #2. If a subsystem is not going to make their part of the budget, make them negotiate with the other subsystems to see if anyone has any excess. I usually withhold 10 lbs as "Engineering Reserve". The team members would rather negotiate between themselves than try to get any of that from me. If we have any left, they get to add decorations, etc. Or I get to add weight to put the CG where it needs to be.

4) Use the CAD tools not only to pay attention to the weight of parts you design, but to decide how much work to do to to purchased parts. We use the CAD models from AndyMark, etc to evaluate different lightening schemes vs. the amount of work. Keep in mind the added benefit of reducing the rotational inertia of moving drivetrain components such as gears and wheels, just don't get carried away to the point that structural integrity is compromised.

4) Design from the beginning with weight as a design parameter. Think about how you can make each part lighter while making it strong enough at the same time. It is much easier to put holes in a part before it is assembled than after the robot is together. Avoid the "we'll just put it all together and see how much it weighs" trap at all costs. It never seems to come back apart to do the necessary work later. Making shavings before you put the electronics in is much preferred to getting metal bits inside them. The holes also look a lot nicer if they are carefully laid out, nicely finished (deburred), and if the part is painted, the holes are too. And if you design them into the part and lay them out properly, you can avoid having an over-enthusiastic freshman drill holes too close to the edge of a critical structural part.

5) Take advantage of the bumpers. You get to rigidly attach a 5" wide strip of 3/4" plywood to the side of your robot. That can provide a lot of structural support if you take it into account during your design process, and it's free weight.

6) See #2.

7) Use creative materials. Composites. Plywood (yes, really. We built most of our 2011 robot from 12mm Baltic Birch plywood). Plastics. Avoid steel unless absolutely necessary, and only for small parts where needed.

8) Pay close attention to the number of fasteners. An ounce here, an ounce there, suddenly you are talking about pounds.

9) Same goes for wiring. Plan your layout to minimize the number of inches of high current (large gauge) wiring runs. This has the added benefit of keeping the resistance down. Just make sure you don't cut everything so short you don't have any slack to work with or that things are so tight they pull out of the connectors.

10) See #2

As I have mentioned on CD before, the three things I say most often during build season are (in no particular order):
1) Is your homework done?
2) That's in the rules.
3) How much does that weigh?

If you pay attention to weight during weeks 1-5, then it is a non issue during week 6. Nothing pains me more as a Robot Inspector than to have to help a team cripple or remove their well thought out game mechanism, rendering them unable to do more on the field than drive, just because there is no way to lighten up their robot enough at the competition any other way.

My final comment on the subject: Thinking you will just drill a few holes in things when you get to the regional if you are overweight is a recipe for disaster, or at least a very non-inspirational event. If you ever think about taking this approach, please sit down and calculate how many 1/4" diameter holes you need to drill in a piece of 1/4" aluminum plate to reduce the weight by 1 lb. I promise you will be surprised.
__________________
Team 5148 - 2014 Wisconsin Regional Rookie All-Stars!!

Mentor: 1379: 2004-2008 / 2530: 2008-2013 / 2861: 2009 / 5148: 2014-??
Lead Robot Inspector: 10,000 Lakes '09 - '11 / Lake Superior '11-'12 / Northern Lights '13, '15 - '16 / Championship '09 - '12, '14 - '15
Attending/Inspecting 2017: TBD, Wisconsin, STL Championship

"Sometimes the questions are complicated and the answers are simple" -Dr. Seuss
Reply With Quote
  #41   Spotlight this post!  
Unread 12-12-2011, 23:42
Ian Curtis Ian Curtis is offline
Best Available Data
FRC #1778 (Chill Out!)
Team Role: Engineer
 
Join Date: Feb 2005
Rookie Year: 2004
Location: Puget Sound
Posts: 2,521
Ian Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond reputeIan Curtis has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

Airplanes have entire teams dedicated to track weights.

Like Burt Rutan said when building Voyager, "If you can throw it up in the air and it comes back down it's too heavy!"

As others have said, but holes in everything from the get go. It requires a little bit of for thought, but honestly it makes robots a very distinctive look. The robots of team 40 were a great inspiration to us as a 15+ lb overweight rookie team, they made everything light from the get go with predetermined wholes that look great, compared to our hodgepodge of holes all over our superstructure.

If you do end up overweight, it is very important to recognize that volume (and as such weight) goes with the square of the radius. A 1/2" diameter hole removes 4 times the weight of a 1/4" hole. Bring big bits.

We had a love/hate relationship with pneumatics. I think it is worth it if you use them for several functions, but if you only need one or two things look long and hard at using motors and limit switches instead. In the two years 1276 didn't use pneumatics we came in well under the weight limit, but we also came in well under the year we used pneumatics for most of our actuators.
__________________
CHILL OUT! | Aero Stability & Control Engineer
Adam Savage's Obsessions (TED Talk) (Part 2)
It is much easier to call someone else a genius than admit to yourself that you are lazy. - Dave Gingery
Reply With Quote
  #42   Spotlight this post!  
Unread 13-12-2011, 07:55
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,811
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Tips on loosing weight (Not spam)

Quote:
Originally Posted by Jeff Pahl View Post
Al, it may have happened once or twice when you weren't around
It's good to know the training stuck!
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
Reply With Quote
  #43   Spotlight this post!  
Unread 13-12-2011, 20:32
Matt Goelz's Avatar
Matt Goelz Matt Goelz is offline
Registered User
no team
Team Role: Alumni
 
Join Date: Feb 2009
Rookie Year: 2007
Location: Indianapolis, IN
Posts: 22
Matt Goelz has a spectacular aura aboutMatt Goelz has a spectacular aura aboutMatt Goelz has a spectacular aura about
Re: Tips on loosing weight (Not spam)

Quote:
Originally Posted by roystur44 View Post
I'm surprised I haven't seen a team make a round tubular frame similiar to a bike frame or go cart frame.
If you search through our belt vs. chain evaluation to find pictures, you will find that we made a round tube chassis for this robot test. However, the closest it got to competition was being used as a "box on wheels" robot to drive around with an attached trailer at the Muncie Scrimmage back in 2009. We used the kitbot chassis for our 2009 robot for simplicity.
__________________
Alumni of FRC Team 234 - Cyber Blue (2009-2012)
Reply With Quote
  #44   Spotlight this post!  
Unread 19-01-2012, 19:43
ThunderTrain ThunderTrain is offline
Registered User
AKA: Captain Thunderman
FRC #1511 (Rolling Thunder)
Team Role: Alumni
 
Join Date: Jan 2012
Rookie Year: 2006
Location: Rochester, N.Y.
Posts: 3
ThunderTrain is an unknown quantity at this point
Cool Re: Tips on loosing weight (Not spam)

We weigh everything every time we change something. this way we can keep track of weight and get our workout in.
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 17:16.

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