View Full Version : Worried about weight ?
SciBorg Dave
07-02-2015, 23:42
As the finished Bot comes together we are starting to worry about the 120 pound max.
Any other teams having weight problems ?
Sperkowsky
07-02-2015, 23:43
As the finished Bot comes together we are starting to worry about the 120 pound max.
Any other teams having weight problems ?
We are fine I picked up the bot today and estimate its only around 40 pounds. But we also have a somewhat short bot compared to many this year.
Christopher149
08-02-2015, 00:00
Last we measured, we should be hitting somewhere around 100-110 pounds (and we're 77" tall).
SciBorg Dave
08-02-2015, 00:07
Last we measured, we should be hitting somewhere around 100-110 pounds (and we're 77" tall).
We are 77 " tall and we will weight the bot with all components tomorrow. We should be about 110-115 pounds.
Definitely. We're about 72" tall, and we're about 128lbs, 8lbs over the limit, and thats not even counting 2 other CIM motors we're planning on using.
Zebra_Fact_Man
08-02-2015, 00:26
Not really. Prototype was only 85lbs and we only plan to add 25lbs more weight to the competition bot.
MrForbes
08-02-2015, 00:28
yeah, it's going to be close this year.
Yeah, we're worried about weight. "Hey, we got any ballast around here, and where we gonna put it?"
The practice bot and a bunch of parts for it hit the scale at under 90 lbs today.
AllenGregoryIV
08-02-2015, 01:05
We're a little heavy for the first time ever. We started figuring out the robot's diet plan tonight.
Jon Stratis
08-02-2015, 01:05
We weighed today, and yes, it's going to be close. Closer than I think we've had in a long time (usually we're looking to add some weight around this point in the season). So, we started a couple of small projects to shave some weight.
We're going to save about 2 lbs (up high, no less!) replacing some 1" angle diagonal cross members (only there to keep things square) with some cables that'll do the same job while in tension - it's a difference of about 150g per cross member, and there are 6 of them.
Another couple of lbs will be shed by replacing some polycarb side shields with corrugated plastic (The shields are mostly there for sponsor stickers and branding purposes).
We're hoping to get the weight low enough to allow us to add some simple bumpers on 2, possibly three sides (attached in <60 seconds on the field). The two sides would help with concerns over an alliance member hitting the side plates and affecting our drive train, and the third one is mostly for visual appeal, although it would add a little extra protection for our battery.
We are 77 " tall and we will weight the bot with all components tomorrow. We should be about 110-115 pounds.
Same situation. All heavy systems are in place and we're at ~97 lbs. Add a few more pounds for air tanks and tubing and that brings us to around 105. Actually first time in the team's history weight hasn't been an issue. Yay CAD model!
Our drivebase was 49lbs in CAD, but only 43lbs in real life. It's really weird.
However, on the whole we are cutting it pretty close.
Bryce Paputa
08-02-2015, 01:33
Eh we'll be fine. CAD says 85 and I think it's close. Should probably get a scale though...
My team cuts it close every season, so we expect to lose some weight. At the moment, we are at around 114 I think, and with some of the things we want to add, we may be hovering at 118-120 like usual.
We're a little heavy for the first time ever. We started figuring out the robot's diet plan tonight.
https://www.google.com/maps/search/jenny+craig+near+Strake+Jesuit+College+Preparatory ,+Bellaire+Boulevard,+Houston,+TX/@29.760766,-95.45711,11z/data=!3m1!4b1
Hope this helps, Allen.
Dave Campbell
08-02-2015, 14:24
Yes, a bit. 129 before powder coat....119.9 after weight loss day. Hope we don't need to add much more this week. We don't have much more to give up without sacrificing functions.
Tristan Lall
08-02-2015, 15:19
Yes, a bit. 129 before powder coat....119.9 after weight loss day.
Over the limit and you powder-coated it anyway? That stuff isn't exactly light, because of how thick it goes on.
tindleroot
08-02-2015, 15:34
Well, we are overweight during build season most years (except for last year), during week 4 the total weight of all our components was over 160! But, after revisions and weight loss we are just under 120 which is good considering the number of mechanisms we have;)
Bonzabonz
08-02-2015, 17:01
What is the best way to weigh the robot? Last year we used a small bathroom scale with a piece of plywood (for the robot to sit on), but we had a lot of trouble reading the scale since it was all the way underneath the plywood and robot. Are there any better ways of doing this, or do you just have to live with a hard to read display?
Jon Stratis
08-02-2015, 17:29
What is the best way to weigh the robot? Last year we used a small bathroom scale with a piece of plywood (for the robot to sit on), but we had a lot of trouble reading the scale since it was all the way underneath the plywood and robot. Are there any better ways of doing this, or do you just have to live with a hard to read display?
There are two good methods I've used. The first requires you to get a scale with a display on a cord - this way you can see the display even when the entire robot is under the scale. Of course, that means you have to buy a new scale.
Perhaps easier, get two scales. You can then balance the robot between them, and have the display sticking out over the side. It's worked for us for a number of years!
MrJohnston
08-02-2015, 18:27
Weighing the robot:
Two years ago, we bought a veterinary scale - it's large enough that we can set the entire robot on top of it and get a very accurate weight. It was well worth the investment.
Our Robot Weight: We cam in at just under 90lbs. the other day and likely added about 10 lbs. yesterday. The robot at this point is entirely constructed aside from a few smallish pieces of aluminium that need to be positioned to help guide totes and recycling containers to their ideal location inside the robot.... And, we might just add one more manipulator, which we'll keep under 20 lbs.
We do cut it close every year, and this year doesn't feel any different than normal.
We weighed our robot today with nearly everything on it and came out to 110 lbs. But that was with the 14 lb battery in it.
This year, we're looking at about 65 pounds again. We'll probably add ballast for stability.
TCMJ1816
08-02-2015, 21:53
We are surprisingly light, most years we ride the 120 line without ballast. We are 77.75" high and weigh ~95 Lbs missing only a banner. We will be adding ballast for sure.
What is the best way to weigh the robot? Last year we used a small bathroom scale with a piece of plywood (for the robot to sit on), but we had a lot of trouble reading the scale since it was all the way underneath the plywood and robot. Are there any better ways of doing this, or do you just have to live with a hard to read display?
We have an electronic "shipping" scale with sufficient capacity, but as we're also interested in finding our center of gravity, we purchased four fish weighing scales last year, and made four stands modified from those metal hooks used to deep-fry turkeys. Last year we went mecanum (totally underestimating the importance of defense), and wanted to balance the weight on each wheel. This year, we've got an H-drive, and we've built it so that we can move the strafe wheel forward or backwards in 1" increments, using the holes in the side rails of the KOP drive chassis. As we now plan to carry up to four totes at a time, then stack two more totes and and RC atop that, we'll probably try to optimize the strafe wheel location for carrying three totes. Knowing the weight at each corner will not only give us total weight, but also COG.
XenObliv
08-02-2015, 22:53
Always worried, weight and time are two of the biggest factors. :eek:
David Brinza
08-02-2015, 23:14
Yeah, I'm worried about weight.
Doctor says I should lose at least 50 pounds. :o
At last check 125 on a scale that reads 2lbs high.
Diet plan involves swapping cims for mini cims.
I think the last year we were overweight was 2008, and we won't forget that lesson. We are closer to 60# than to 120# now, with everything but a few sensors and cables attached.
Chris Endres
08-02-2015, 23:18
not worried at all...
we are 25 pounds to the good with the robot done we just have to support a structure better wich shoudnt come close to 25 pounds
Bryce2471
09-02-2015, 02:12
We weighed in the practice bot, when it had almost everything mechanical on it, but no electronics. It weighed 95bls. Then we weighed in after it was completed, and it weighed 130! D:
Thankfully, with some quick thinking, we weighed it in the next day at 116lbs, without sponsor panels. (We didn't even have to abandon features or swiss cheese!)
Thad House
09-02-2015, 02:23
We weighed in the practice bot, when it had almost everything mechanical on it, but no electronics. It weighed 95bls. Then we weighed in after it was completed, and it weighed 130! D:
Thankfully, with some quick thinking, we weighed it in the next day at 116lbs, without sponsor panels. (We didn't even have to abandon features or swiss cheese!)
Ah. the good ol' "Forgot about the battery" 14 lbs.
125 lbs with almost everything on it (-battery)
Time to hit the chop shop
We weighed in the practice bot, when it had almost everything mechanical on it, but no electronics. It weighed 95bls. Then we weighed in after it was completed, and it weighed 130! D:
Thankfully, with some quick thinking, we weighed it in the next day at 116lbs, without sponsor panels. (We didn't even have to abandon features or swiss cheese!)
What were your sponsor panels made from that they weigh 14 pounds?
I hope you got lots of $$ if they are such "heavyweight" sponsors ;)
BBray_T1296
09-02-2015, 09:11
What were your sponsor panels made from that they weigh 14 pounds?
I hope you got lots of $$ if they are such "heavyweight" sponsors ;)
No size limit means a 26'x6.5' banner with sponsors on it.
We're worried about weight. We put up a couple of stacks this weekend and all of that's well under weight. We've known all along that we'd want to add a specialty mechanism or two, so we've been fairly weight-conscious about everything. If something will be CNC'ed, we save as many ounces as seems practical. If something will be manual milled, we try to do holes, slots or planing. Not everything got done in its lightest form, but I can't complain that we have an integrated robot with a 9/10 primary mechanism at the end of Week 5.
The good news is, it looks like our entire specialty mechanism will fit in under the 30lb withholding, so we can keep that back for more tuning and focus on driver practice while we can.
It's the first time we've ever actually worried about weight - the rest of the years we knew where we were but didn't have to modify anything specifically to get under weight. c.g. isn't the best, but it hasn't been an issue yet during practice.
Addison4300
09-02-2015, 13:50
We are fine I picked up the bot today and estimate its only around 40 pounds. But we also have a somewhat short bot compared to many this year.
40lbs.?! WOW! I think that is the lightest robot I have seen. Ours is currently at 115lbs.
MrForbes
09-02-2015, 13:51
...or maybe someone is stronger than he thinks he is?
SciBorg Dave
09-02-2015, 14:44
What is the best way to weigh the robot? Last year we used a small bathroom scale with a piece of plywood (for the robot to sit on), but we had a lot of trouble reading the scale since it was all the way underneath the plywood and robot. Are there any better ways of doing this, or do you just have to live with a hard to read display?
We are a 4-H team we use a scale for weighting hogs and sheep. Very portable and light weight. Call your local 4-H in your area.
Bryce2471
09-02-2015, 16:22
Ah. the good ol' "Forgot about the battery" 14 lbs.
No, we didn't forget about the battery... that would have been too easy! ;)
What were your sponsor panels made from that they weigh 14 pounds?
I hope you got lots of $$ if they are such "heavyweight" sponsors ;)
Lol! No, the sponsor panels only weigh a couple pounds, but we ended up removing some of the light weight structure that our sponsor panels were attached to, so they will need to find a new home.
Dragonking
13-02-2015, 06:22
If we put everything we wanted to on our robot we would be about 30lbs overweight. Just the bare minimum is already pushing 120. So yeah, we're getting the saws and drills ready.
Anupam Goli
13-02-2015, 09:05
Final practice robot weighed in at 126.5 lb. Started doing some budgeting and calculations, looks like we're replacing our 8020 super-structure with 1/16" tubing. Looking to have atleast 4+lb left over to use as ballast.
The_ShamWOW88
13-02-2015, 09:11
We're always at the limit so it's a worry but nothing we haven't dealt with. We're currently sitting at about 105 pounds, gives us a little bit to play with in case anything small needs to be added or it at least gives a little play to add some additional weight as a ballast.
kjohnson
13-02-2015, 09:20
This is the first time we've been concerned about weight in years. In the past we've used Lexan sheets to display our sponsors and cover electronics from damage but this season we've had to print stickers and apply sponsor logos directly to the frame. We even cut our 3' ethernet cable in half to save an ounce. Currently weighing in around 124, some basic refinements should get us down to 120..
MrForbes
13-02-2015, 09:20
According to my antique bathroom scale, we're at 105....and breathing easier.
Jon Stratis
13-02-2015, 10:08
This is the first time we've been concerned about weight in years. In the past we've used Lexan sheets to display our sponsors and cover electronics from damage but this season we've had to print stickers and apply sponsor logos directly to the frame. We even cut our 3' ethernet cable in half to save an ounce. Currently weighing in around 124, some basic refinements should get us down to 120..
If you can get down to the point where you have a little weight to space, get some corrugated plastic (I found some at home depot, underneath the Lexan) and put sponsor stickers on that. It'll have a similar end look as if you put one big sticker over a sheet of Lexan, but weigh significantly less. For side shields on our robot (maybe 1.5'x2'), replacing a Lexan sheet with corrugated plastic saved us a little over 1kg per sheet.
Team 5137 has only 6 pounds to spare (without battery) at 114lb and 77.75" high
Still thinking of adding another arm to sweep with those "extra" 6 lbs
Dunngeon
14-02-2015, 22:54
114.2 lbs today before our first design revision. 115.8 after
A little close, may need to make a couple pieces lighter so we can add a component or two before competition.
We're sitting at 123. Changing our drivetrain cims to minicims and we'll be really close.
waialua359
14-02-2015, 22:58
We're sitting at 123. Changing our drivetrain cims to minicims and we'll be really close.
Know the feeling.
We spent 1 1/2 weeks losing 17 pounds down to 118-119 now.
Swapped out and/or got rid of CIMS for banebots.....6 to 2 now.
Those were easy.
Lightening or redesiging parts took forever equating that to trying to lose weight real life!
We bagged "Peabody" about 45 minutes ago at 107.2 lb. We have an H-drive, and were worried about the CoG. We initially mounted the strafe wheel based on our week one SWAG of the final CoG. Our strafing didn't show any noticeable rotation, so we figured we were close. Weighing of the four corners shows that we missed by about 3/4". We didn't bother moving the wheel back.
We did pull about 10# of gear, mostly the front fork assembly, excluding the lift plate. This assembly has 20 spring-loaded bolts, 6 limit switches, a flipper/holder "plow", and two rows of RGB LEDs. We weren't happy with our reliability at lifting the totes, so we'll be rebuilding this part before Bayou (week 4). After seeing some of the week 0 reports, we may opt for a fixed (and thinner) grabber than our 10-32's.
This leaves us another 12-13 lb to play with to stay at/under weight, and another 7-8 lb of fabricated spares in our withholding allowance. We may use some of the weight on some bits to help align stacks as we build them, and the rest on ballast to get the COG right, and to increase the weight supported by the strafe wheel, which seems a bit light; the aluminum angle must be flexing more than we thought it would.
The programming team is meeting Monday to work on sensors and automation using "Atlas," which is the first built of our robots. Apart from the bits that were not finished or need rework on them, the two are nearly identical. The biggest difference is that the two fork assemblies are built on different spacings between the vertical risers; this is another reason we pulled the fork assembly.
Without pneumatics and electronics, our robot weighs ~90lbs.
We're not worried. In fact, we're so un-worried that we even added some fairly hefty handles to our robot so that we can pick the thing up without torturing ourselves this year.
Zebra_Fact_Man
16-02-2015, 09:43
We weren't worried, then we weighed in at 145lbs!!!
Today is weight-loss day. We have a plan that should take 28 pounds out of the frame. Wish us luck!
Jon Stratis
16-02-2015, 10:24
We weighed on 3 different sets of scales (outs and ones provided at two week 0 events), and all agreed... 113 lbs.
Then, we broke a critical component of the robot and spent probably 15 hours working on a redesign. Time to weigh again... I think the redesign may add a couple of lbs, but shouldn't take us over weight.
nicholsjj
16-02-2015, 11:05
We understand the pain in this thread. The team had been so good with Solidworks keeping a weight chart for the robot [arts and thought they had 5 lbs. to spare. We had a parent bring in an industrial scale, thankfully, and poof they realized they forgot to add our clapper assembly as the robot's weight was at 135. After rebuilding the top of our four bar from 2X1 tubing to 1X1 tubing the robot weighs in around 119.5 with a better COG. We had to take off our fancy 3D printed numbers and second signal light though :(
Were somewhere around 78" tall (depending on active configuartion), 42" long and weigh in at like 119.5 lbs. Ya....
mman1506
16-02-2015, 19:49
We're at 81.6 lbs, which is way less than I was expecting. We brought in 2 other scales just to confirm.
Just over 110 on our bot. It has everything besides sponsor panels! Its nice not being underweight like last year.. (90 lbs) we always lost in pushing wars :(
Just over 110 on our bot. It has everything besides sponsor panels! Its nice not being underweight like last year.. (90 lbs) we always lost in pushing wars :(
Phew! You should hold up in pushing wars this year just fine.
MrForbes
16-02-2015, 23:21
This year, we get to worry about the falling over wars instead.
Billfred
16-02-2015, 23:28
4901 will be right on the line, but I'm not concerned since we have a few pretty simple outs with our design. I haven't had to put a robot on a crash diet since 2006, why start again now?
108lbs. Literally 1lb less than the cad. I'm so happy.
That leaves room for more subassemblies... we ahve two robots so we can test.
Zebra_Fact_Man
17-02-2015, 01:41
We weren't worried, then we weighed in at 145lbs!!!
Today is weight-loss day. We have a plan that should take 28 pounds out of the frame. Wish us luck!
Got our robot down to 113 lbs. That's 32 lbs we cut in 1 day!
We weighed our robot on Sunday night and got 128 pounds. We removed some parts that were not mandatory and got it down to 122 pounds. Unfortunately, there were still parts that needed to be added. Some parts were remade using 1/16 inch wall tubing instead of 1/8 inch wall tubing. Today was a long session of "alumi-suction" and we ended up at about 118 pounds. Tomorrow, will be more sessions of alumi-suction to lose more weight so we have margin for adding to our mechanisms.
z_beeblebrox
17-02-2015, 08:39
105 lbs. Close enough to think about weight but not close enough to worry. We'll be adding a little at our first regional.
The_ShamWOW88
17-02-2015, 08:50
Weighed again last night, just about 105, enough room for us to figure out what to use to push the noodles out of our way...
The robot spent the last 3 days out in the warehouse spa under going weight reduction therapy. 119.8 A cylinder swap should keep us just under
We were over but did a lot of weight reduction to get to 115
wilderbuchanan
17-02-2015, 10:00
Last night we drilled 200 1.5 inch holes and removed every possible thing that we could and were down to 119 using pressure pads. Were cutting it way to close.
Abby_Schuett
17-02-2015, 11:02
Our team recently weighed our robot as well. It was ten pounds over; so the past two nights have been spent drilling holes and replacing parts with lighter options. I think we're still four pounds over, so the robot is going to look like Swiss Cheese.
Just_a_cat123
17-02-2015, 11:49
Yes, my team, 4456, robot, when we weighted it this last Saturday, was 162.5 pounds, 42 and a half pounds overweight. Our robot was suppose to pick up 5 totes at once and drop them all at once with an accordion forklift design, which turn out to be to heavy. Therefore we spent that last couple days on the biggest robot loser mood. Also, sense my team is centered in northwest of the District of Columbia this storm is really slowing us down.
114 lbs according to the bathroom scale + plywood base method. No idea what the error range on the scale is, but needless to say nothing else is going on the bot...
SciBorg Dave
17-02-2015, 14:45
We weighted it yesterday. 1.6 pounds over weight, we already know how to reduce the bot. So we are in good shape.
orangemoore
17-02-2015, 15:20
We don't know how much we weigh but we know it is less than 100 lbs with a battery. We will find out the true weight at our week 6 regional.
xXhunter47Xx
17-02-2015, 15:45
We've started to strip unused conductors from CAT5 cable to save weight
s_forbes
17-02-2015, 15:46
Maybe we'll invest in some balloons. Size limitations this year are great!
http://i.imgur.com/zC6UvvZ.png
73 pounds. We still have to make our forks/tote grabber with the withholding allowance to bolt on Thursday and some sponsor panels but our critical systems aren't even going to get us to 100. Which means lots of room for a counter weight!
Sperkowsky
17-02-2015, 21:19
Funny we were not worried about weight the entire season. We weighed it today and it was 117 pounds........ Well that could have been bad.
jimbo493
17-02-2015, 21:30
We came in at about 119.5 So we are a bit worried since we like to leave a little for varying scales, but we cut about 3 lbs today to get us into the legal side of things, at the start of the meeting we were 123.
Tristan Lall
17-02-2015, 23:31
Maybe we'll invest in some balloons. Size limitations this year are great!
http://i.imgur.com/zC6UvvZ.png
As I'm sure you know—but in case others haven't considered this—weight does not include buoyancy. Our conventional methods for measuring weight don't account for that source of error, but with most robots it's negligible.
If you bring an inflatable robot to inspection, I wouldn't be surprised if the inspectors make you calculate the weight of the contents of the gas bag, and incorporate it into your official weight.1
1 By implication, the gas bag can't be a pneumatic part (arguable, depending on the robot's configuration), and the gas is a part (and by further implication, so should be the air in your pneumatics). To avoid those inconvenient complications, instead use a large, lightweight chamber full of vacuum.
dtengineering
17-02-2015, 23:53
As I'm sure you know—but in case others haven't considered this—weight does not include buoyancy. Our conventional methods for measuring weight don't account for that source of error, but with most robots it's negligible.
.[/SIZE]
I find myself compelled to disagree.... which is probably a sign that I should really be doing something useful or productive instead, but hey... this is more fun.
The FRC standard for measuring weight is to place the robot on a scale. In keeping with FRC precedent and in lack of guidance from the Q&A, I'd have to assume that the manual specifically chose the word "weight" rather than the word "mass" because the rule reflects the method of measurement.
Of course if FIRST was based on international standards for science and engineering, they would have a rule requiring the robot to have a mass of 55kg or less, and the point would be moot. Even specifying a weight of 55kg or less would imply a mass of 55kg or less as the gram is specifically a unit of mass, not a unit of force. The pound is an imprecise unit specifying neither mass nor force. Given that the people who wrote the rules are aware of the difference between mass and force and chose to go with an ambiguous term, it is only fair to conclude that they did so intentionally and give the benefit of the doubt to the team.
I also feel compelled to argue for the legitimacy of the balloon as a robot component. Other pressurized vessels, such as gas shocks and pneumatic tires are allowed, so long as they are not connected to the robot's pneumatic system. In the event that a sealed balloon was disallowed for some reason, there is no requirement that the buoyancy come from a sealed vessel. Hot air balloons work nicely with an opening.
I will now remove my tongue from my cheek before it causes permanent disfigurement! :]
Jason
P.S. The "anchoring" thing wouldn't work, however, as the robot must meet the weight limit in its starting condition. This might cause some grief with maximum height requirements.
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