pic: First Custom Chassis
 

Re: pic: First Custom Chassis
 

...there's cross members, right?
Bellypans provide support but not all types of support.

Re: pic: First Custom Chassis
 

yes we have a top cross bar just not shown in picture

Re: pic: First Custom Chassis
 

Just a top bar? It's hard to provide moment reactions with just a bar linked in at one point per side.

Re: pic: First Custom Chassis
 

what would you recommend?

Re: pic: First Custom Chassis
 

Top is what I'm interpreting that you have planned, bottom is what I would suggest. Something that links in at multiple points so that the combination of force reactions produces a moment.

https://goo.gl/photos/wxTJnghMbhq163Md7

Something like

Re: pic: First Custom Chassis
 

Out of curiosity... how are you attaching bumpers to the front/back corners? You'll need some sort of frame member extending past the wheel on the corner, but your outside plates appear to stop short.

If it were me, I would add support with some more C or square tubing across the front and back. Bolt it into the existing C channel and into the belly pan.

As an example, here's our custom chassis this year (We've only done a custom chassis once before, in 2009).

Re: pic: First Custom Chassis
 

were building an upper structure that will pertrude outward past the tires while still being under 15"

Re: pic: First Custom Chassis
 

Is that the base for a turret?

Is that a mechanism for determining the width of your chassis? :D

Re: pic: First Custom Chassis
 

We had a similar design a few years back in 2012 and we ended up having turning issues. We had gearboxes on our corner wheels then chain running from the rear wheels to the center wheels all 6 wheels were powered but this still caused some turning issues. At the time we also had the same exact tires on our robot. What will happen when turning with a drop center design is the weight is going to transfer to the middle wheels (powered) and the front corner wheels (unpowered). When this happens only 50% of your powered wheels will be touching the ground and it can cause some turning issues. A simple fix for this would be to add another belt run from the center wheels to the front wheels, your team could do this in a multitude of ways. Let me know if you have any more questions, good luck!

Re: pic: First Custom Chassis
 

Looks nice!

I'm curious about the plywood bases for the bumpers in the corners -- it almost looks like they may be screwed right in to the frame (unless those are captive fasteners I see and the bolt comes in from the robot side and is removable) and would be hard to remove from the robot after the fabric is added.

Re: pic: First Custom Chassis
 

The plywood for the bumpers is bolted into the 1x1 uprights, which then fit into slotted members that are welded onto the frame. We'll be drilling straight through the bracket and the 1x1 uprights to add some pins to hold it together. In the picture above, the bumpers literally can be pulled straight up and off the robot.

But, it is nice to have the bumpers proceeding apace with the rest of the robot! Fabric should be screen printed and ready for sewing sometime next week, and by then we should have the attachment process finished.

With manipulators that hang outside the frame perimeter and needing to get down to the ground, having bumpers in place early is an absolute must!

Re: pic: First Custom Chassis
 

I spy a tape measure.

Re: pic: First Custom Chassis
 

It is very nice to see a robot where the bumpers are not an afterthought.

Re: pic: First Custom Chassis
 

How else do you measure your bumper length?:confused: :confused: :confused:

:D