We do a combination of ideas already mentioned. We keep track of individual weights right from the start as we check the kit of parts. The wrestlers have an awesome digital scale that they let us use.
Last year our robot weighed 119.6 pounds when we loaded it into the crate. And it weighed 119.8 pounds when it was checked at competition.
Moral of the story… leave room for error.
Hi Guys,
Need an inexpensive scale? Try this for $49:
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200307409_200307409
It only goes to 110lbs, but that should probably be a good goal anyway …
They have scales that do more weight - search on “Hanging Scales”
We just use a bathroom scale and tip the robot up on one edge, balancing it with one finger, While this is admittedly kind of dicey, it is accurate enough so that we have a good idea whether we are legal or not. When we have gone to a scrimmage or regionals for an official weigh in, we generally aren’t to far off the mark, and we haven’t had to shell out $$$ for a pricey scale, or drive to a different location to get an estimate of weight. Quick and cost effective.
I have a theory for weight management for the robot. In the shop the robot usually weighs in OK, the problem is when we unpack it is mysteriously over weight! I think the robot does some eating while at drayage or on its FedEx trip. Influenced by our heavy pizza eating during build the robot makes poor dietary choices causing it to gain unwanted weight. This year i will weigh the robot on the scale in the trainer’s office. I think the robot will get jealous of the featherweight wrestlers and will suck it in as to not be over weight. To aid in the shipping process I plan on hanging a poster of the new food pyramid and hope for the best!
Best of luck everybody and think thin!
-Jordan
scales in the school cafeteria
Last year we were 0.8 pounds under the maximum weight. We calculated just by parts… We took alot of weight off just to be safe.
Wrestling Scales and Shipping Scales here at the university.
We use two identical bathroom scales, putting one under each end of the robot. Add the two readings and we have the weight of the robot. It’s not perfectly accurate, but usually close enough for us.
In 2006 we used four old bathroom scales (one in each corner) and we were off by about 20lbs (thought we were ~5lbs under, and really were 15lbs over). Last year, we used a large scale a parent had, stuck a sheet of plywood on it, zeroed it, and then placed our robot on it. We thought we were tenish under and really were five under. I think part of the issue in 2006 was that we used freshmen to zero our scales (I’m not kidding, we had freshmen who new their current weights very accurately [from sports] and used them to zero our scales), and since the human body fluctuates so much (as any wrestler can tell you), our zeros were all kind of iffy.
Yes, Team 766 puts a board on a scale, zeros and loads on the robot. Also, if you weld the robot, remember the extra metal. We were able to gain space and lose quite a bit of weight just by angle grinding down our aluminum welds.
I have found that you can hide the parts that you don’t want to mass, and then unclick the check box that includes hidden parts in the mass. Not exactly the cleanest way to do it, but it gets the job done. Select the entire assembly (That should show up as one item in the mass list if you are doing this correctly) when you do this.
My preferred method is to just mass each part one by one, and then add the masses up in your head. I am just too lazy to hide the other parts.