Chassis weight

Would anyone have an idea what the average weight would be for a mostly completed chassis. Frame, gearboxes,wheels and motors.

[treffk]

It all depends on your design, drive train and what you are hoping to accomplish for this years game.

For example my students have calcuated that in motors alone we are going to have about 50 pounds of weight with their current design.

If you are just wanting a defensive bot you wouldn't need nearly as many motors or an elaborately designed chasis. If you are wanting to climb or shoot depending how how you design these systems they could also use motors and gearboxes thus changing the weight for every single team. It's difficult to predict an average weight because everyone's and every teams thought processes are different along with their skill sets.

Thanks for the info, our group has been working on a direct drive mecanum system. The frame, gearboxes, motors and wheels weigh 47 lbs with a perimeter of 108 inches. I am not sure we want to cheese out the frame any more than it is. At this point it only exists in SolidWorks.

[treffk]

That's okay! Ours only consists in to scale drawings and a 1/3 scale cardboard cutout.

[pmangels17]

Our drive generally averages around 30-40 pounds. However, in 2011 we built a crab drive (with freshman builders and one sophomore, might I add) that weighed approximately 50 pounds. However, you could easily make a lighter custom one or a lighter one using the kitbot. It all depends on your goals.

[Donut]

I think the average is in the 30-40 lb range. We did Mecanum last year with very large standoffs and full size Toughboxes for each wheel (read: overkill) that weighed in at a whopping 60 lbs for the frame, wheels, gearboxes, and motors. This year we're trying out the Nanotubes from Andymark and the new Mecanums from VexPro, I think it should weigh in at around 30 lbs for it all.

Mecanum systems will tend to be a little on the heavier side due to significantly heavier wheels and an extra pair of transmissions. Direct drive should help keep the weight down some without chain or belt needed. Are you using stock gearboxes from Andymark or VexPro, or are these custom? There are quite a few low weight transmissions out there now that can save you some weight.

[akoscielski3]

My Chassis' on average weigh about 40lbs. Try to keep it under that.

[pmangels17]

The shifter transmissions we ordered this year were around 8 pounds with a motor and shifting cylinder installed. However, we took off the side plates and replaced it with the star shaft that comes in the kitbot, and dropped a pund already between the two. THere are also some extraneous mounting brackets that could be cut, and some holes in the side plate (or thinned out areas) that could be taken out for more savings, but we will probably keep the plates stock. We are only using to drive transmissions this year, so we should be okay. Transmissions make up a huge part of your weight, so consider your power distirbution wisely.

We are planning a .080 5052 box style chassis, the gear boxes are a modulox inspired design with Aluminum gears and shafts. We went with an 8 inch wheel due to clearance issues with the 6's. The wheels alone are 10 lbs. I also made an error our weight at this point is 44 with the motors.

[bardd]

Originally Posted by DMike

Thanks for the info, our group has been working on a direct drive mecanum system. The frame, gearboxes, motors and wheels weigh 47 lbs with a perimeter of 108 inches. I am not sure we want to cheese out the frame any more than it is. At this point it only exists in SolidWorks.

47lbs is quite heavy, though you should avoid cheesing it out just yet. First finish CADDing the whole robot and see whether you pass the weight limit or not. If you don't, it'll be better keeping the chassis heavy than cheesing it out and losing structural strength.

[Peter Matteson]

Originally Posted by DMike

Would anyone have an idea what the average weight would be for a mostly completed chassis. Frame, gearboxes,wheels and motors.

Our lightest most basic and optimized 4 motor, 2 speed, drop center 6WD in that state was 35 lbs. Our articulated drivetrains tend to be about 10-15 lbs heavier. I would say anything in the 40 lbs range is normal.

[Alan Anderson]

We weighed our practice chassis yesterday. Without the second gearbox, two CIMs, and cross-frame support, it came to 25 pounds. I'm guessing it'll be just under 40 pounds with all structure and motor speed controllers installed, before adding the brain box.

[LightSpeedIII]

According to our CAD, our drivetrain should weigh approximately 25lbs.

[nathan_hui]

Originally Posted by LightSpeedIII

According to our CAD, our drivetrain should weigh approximately 25lbs.

Did you take into account the 5 lbs or so of bolts, nuts, and washers that usually come together with a chassis? As well as each motor's actual weight?

[Chris is me]

Originally Posted by pmangels17

However, we took off the side plates and replaced it with the star shaft that comes in the kitbot, and dropped a pund already between the two.

I think this is a really bad idea. Those hex shafts are designed to be used as spacers, not as drive axles. That part could easily fail when you need it the most.

Spend your weight where it matters. The drivetrain matters.