Prototype 6WD that our team has been working on over the off-season. Depending on availability of welding equipment and personnel during build season, the 80/20 may end up being box aluminum instead. Thoughts?
Nice every thing looks good. 1 question; is there any reason you don’t have any supports for the back wheel’s? just curious.
Not too bad. It’s great that you’ve CADed electronics and thought that out pretty well.
I’d say that the top of your frame might not need so much support. You can probably cut out the inner long rails and just make it one big rectangle with cross bracing and corner supports. That should save you a few pounds.
That will be one tough chassis.
From our experience I’ll point out some things to be aware of.
- IF you can weld, box tube is lighter, but not as convenient.
- The wheel mounts may work loose and slide in the 80/20 rails. Make sure to fasten them securely!
- Impacts will cause the frame you show here to loosen and shift. Make sure to through bolt or gusset your corners and joints. (Again, this is where welded box tube can be superior.)
As long as you plan ahead for the rigors of competition, this frame design should server you well.
I have one comment in addition to what’s already been said. You ought to take a look at how accessible the electronics are. Electronics that can’t be reached are no fun. Trust me. Make sure you have enough space to get to them, to reach important plugs and connectors, and to bring in and use tools, like the Wago tool. You might even want to consider a removable electronics board.
Other than that, lookin’ good! Keep up the good work!
You could probably do away with several chassis members and still be tough enough for just about any game in the Bumper Era
We have used T-slot extrusion (Bosch 20mm rather than 80/20 because we can get it at cost) for our frames since 2005 and they have served us well - only in 2010 with the vigors of bump crossing (and some weight problems resulting in fewer cross members than we would have liked) have we had any structural problems.
We have learned a few things about these types of frames through the years:
Through-bolt wherever possible. At the very least, leave it as an option. Remember that a 3-way joint is impossible to through-bolt when it’s in the middle of a frame member (like on the front of this design).
If your extrusion manufacturer offers multiple types of “corner cube” connectors, go with the beefiest one you can get. Direct impacts have shattered our corner cubes in the past.
If we are going to use T-slot connectors on a particular piece, we prefer to use slide-in (not drop-in) T-nuts for the strongest connection. To facilitate easier insertion, we often mill the T slot wider somewhere near an end to provide an insertion point.
Think long and hard about using the T-slots for holding your pillow blocks. While having a sliding axle makes tensioning a chain trivial, locking it down in place requires that you diligently tighten everything after EACH match. Using a cam bolt or turnbuckle to make sure your pillow blocks don’t slide can be a good idea if you can figure out how to do it in a lightweight way (usually we just through-bolt and add idlers for tension if necessary).
I can tell you that the design just as you have it will make for a rock-solid frame that will serve you well! Good job.
Also, another possibility if you want the weight of box tubing but not the challenge of finding a good welder: 8020 Quick Frame.
really nice job.
Like others have said probably a bit too beefy.
Welding will save you a ton of weight just in fasteners.
Instead of welding we use gussets, rivets, and good epoxy and haven’t had a frame failure in the two years we have used this method.
Any reason the Gaming Adapter is so low in the Chassis? You might have some signal issues, though I’m no expert on the subject.
If we applied the previous years’ rules regarding frame behind the bumper, the corners of this frame wouldn’t pass inspection. The entire length of the bumpers must be supported with no gaps under those rules.
I’d also put a bearing into the plate with the live axle coming off of the super shifter. The 80/20 is great in that you will be able to make minor adjustments to keep the bearing perfectly aligned.
Other than that I think it looks good for a preseason prototype.
This is solveable by replacing the aluminum angle with a regular 80/20 member, and using 80/20 corner anchors to attach the frame members together. The round pockets for the corner anchors can be milled in either a milling machine or a carefully aligned drill press jig.
If you do use the 80/20 inserts above be sure check them for tightness after every match and use Loctite. They tend to vibrate loose because they don’t have the natural “lock washer” properties of things mounted on the sides of the extrusion. These little inserts are very strong and much lighter than L brackets and plates but they can be a pain if they become loose in a hard to access place.
Thank you guys for all of the comments thus far!
This will be our first year building just about anything with 80/20, and to go straight to a frame with it is a little nerve-racking. All other robots we’ve ever built have been either box or angle aluminum, welded by one of our sponsors. Unfortunately, we don’t know if we have that option yet, and that was the impetus for trying some CAD with 80/20.
I appreciate the advice on tightening methods, because that’s one of the key things we’re worried about. Also, thank you guys for the mention of not needing as much support as we’ve added. I’m going to bring this info to our next meeting and we’ll work accordingly.