Tips on loosing weight (Not spam)

[Chris is me]

Originally Posted by IKE

Be careful with aluminum gears. When done right, there are some significant weight savings opportunities, but know that is is difficult to do them right. Aluminum has several properties that are quite poor for gears. Many gear experts would recommend to NEVER use aluminum. I do think they have their place, but you should be extremely careful and really need to know what you are doing.

Lightening the steel gears, while not particularly FUN to do, isn't very hard and will get you a decent amount of the way there with regards to weight savings.

Originally Posted by Gdeaver

Composites can save weight over AL. If I remember correctly, This years arm which was made of pultrutions and polypropylene weighted 65% compared to the same structure in AL. Working with composite require methods that are different than working with metal. Do the research before using them.

I'll put in a vote for composites as well. Pultruded fiberglass is very rigid, thick stuff with a low density. Fiberglass tubing is great for something like an arm.

[IKE]

Originally Posted by Chris is me

Lightening the steel gears, while not particularly FUN to do, isn't very hard and will get you a decent amount of the way there with regards to weight savings.
.

Absolutely, I can't believe I forgot to add "lightening" steel gears. For those that are not familiar, you can either cut pockets with a mill, or undercut the gear between the teeth and the hub on a lathe (this is what we usually do). When doing this, make sure to leave a littl material underneath the root of the gear tooth as this can be a highly stressed location on a gear. Also leave material for the hub as this is either the torque transferring area, or has the bearings on an idler gear. We can often cut about 50% of the weight out of the standard AndyMark gears.

Just be careful how you "cuck up" the gears in a lathe so you do not damage the teeth.

[EricH]

Originally Posted by IKE

Absolutely, I can't believe I forgot to add "lightening" steel gears. For those that are not familiar, you can either cut pockets with a mill, or undercut the gear between the teeth and the hub on a lathe (this is what we usually do). When doing this, make sure to leave a littl material underneath the root of the gear tooth as this can be a highly stressed location on a gear. Also leave material for the hub as this is either the torque transferring area, or has the bearings on an idler gear. We can often cut about 50% of the weight out of the standard AndyMark gears.

Just be careful how you "cuck up" the gears in a lathe so you do not damage the teeth.

You can do the same thing with sprockets. Just be careful, for the same reasons. A couple of large sprockets have failed catastrophically in competitions after being lightweighted. I remember or remember hearing about two incidents from 2004--in one case, the sprocket turned into a pretzel; in the other, the hub broke free after the season, disabling that particular robot by removing one of its highest-traction wheels from the drivetrain.

[ratdude747]

One trick to saving weight is to get rid of unnecessary parts.

Another thing i advise teams NOT to do is to use plastic chain where any significant torque is involved... I've seen it bomb catastrophically before... remember that with chain, one weak link ruins the whole loop.

Agreed on using 1/16" where possible...

one last tip is that if you have to resort to cheese-holing, do it to low load things higher up on the robot... having a low center of gravity is key to a stable robot. every little bit helps.

[Jon Stratis]

The biggest way to lose weight... Ask the inspector to take his foot off the scale

We've never really had a problem with weight on the robot... In fact, most years it's the exact opposite! We always end up either significantly under weight, or spend some time figuring out how/where to add weight (2008 we had a 20lb steel plate bolted to the very bottom of the robot, 2009 we bolted steel plates outside of our cantilevered wheels to support the bumpers, 2010 and 2011 we were under weight - 2011 by quite a bit).

You need to consider weight with everything that goes on the robot - it's easy to "over-engineer" something by building it with bigger/stronger parts than are really needed. What's difficult is building something to be just as strong (and thus heavy) as it needs to be, and no stronger.

[Al Skierkiewicz]

Originally Posted by eagle33199

The biggest way to lose weight... Ask the inspector to take his foot off the scale

Cmon! Jeff and I only did that to you once! OK maybe twice but that was all I swear!

[JamesCH95]

Originally Posted by Chris is me

I'll put in a vote for composites as well. Pultruded fiberglass is very rigid, thick stuff with a low density. Fiberglass tubing is great for something like an arm.

As with anything, overkill can be spectacular:
http://www.carbonfibertubeshop.com/t...roperties.html
http://www.dragonplate.com/ecart/categories.asp?cID=88

But I agree that any composite can be a great way to cut weight.