We’ve never used the kitbot frame, but it just seems entirely implausible that the bare kitbot chassis could weigh more than that. Maybe with gearboxes, chains, motors, and wheels?
its supposed to be 21.2:ahh: (i did my math wrong)
i used the 2x6’s because 3/4inch plywood in florida is $32
and I was thinking about using a bearing block as well as a ball bearing in the wood itself for the canitleverd wheels
also i wanted to be able to use screws as well as the liquid nails…
i figured the extra weight was worth it
and i wanted to be able to just bolt our supershifters to the wood also
We found precut 1/4 sheets (2 feet x 4 feet) of 3/4" birch (cabinet) plywood at 3 different building supply places for about $14-$18. Sutherlands, Lowes and Home Depot have it in stock.
not really, the kitbot after we put the four cims and two supershifters and all the electronics and chains and (IFI)wheels was just about 36 pounds,
with the wooden frame, im planning on using directely driven (AM)wheels and only two chains, the BB transmission should work nicely,
im still deciding weather we should use the supershifters or the banebots(i think this is were the weight could be made up ot lost), its really all a matter of what we want to use if for(probobly just for testing and demos)
i still think it will be lighter(even if its only by a pound ill be happy)
That’s going to be a *seriously *strong chassis. Once you get all your components mounted, get yourself a 2" spade bit and whack some speed holes down the center line of those 2x6s. Remember, the stiffness of a beam goes up as the fourth power of its cross-section. 2x6 studs are really, really stiff on edge – and the breaking point is also very high. You can easily remove material without compromising strength below a danger point. That 3/4 ply is heavy, too. Do you have a piece of 1/2" you can use? You really don’t need that 3/4.
On the other hand, a cheap, strong chassis. Have fun!
total cost for the wood was $26.79 and most teams have should have everything else i used
Home-depot was out of 1/2 inch 1/4 sheets…(would probobly save a pound or two without compromising strength)
thats really what i was going for with the wood,
its going to be 6wd if we have enough of the AM wheels left
it is really strong, i dropped it, kicked it, jumped on it , stood on it, and hit it with a hammer repetedly(and im not a small person) the only thing im concerned about is taking an hit on the side, and cracking the 2x6(but there will be bupers so it shouldent be that big of a problem)…
oh and interestingly, i think the bottom panel added a lot of stiffness, before i had it on, it would kinda flex out a litle bit
A Banebots 12:1 2 CIM gearbox is 3.75 lbs so that’s still 7.5 lbs.
I can’t imagine the kit wheels are a whole lot lighter than the Plaction wheels, they are probably heavier.
Of course the base will be lighter if you start removing functionality. comparing this base as a 4WD with 2 CIMS to your base last year is not an apples to apples comparison.
no, have one, single cim gearbox on each side… with a single chain to the other
our base last year was 2wd with 4 cims
if im only using two victors, and the main block, and the power distribution panel, it should be around 8 or 9 pounds. weight isent really a concern for this, i just wanted to make it strong enough and still be lighter than the kit chassis with everything on it, just wanted to prove a concept to myself and my team
When we made ours, we did not attach the ends to the sides at all. We glued/stapled the sides to the bottom, then glued/stapled the corner gussets on the top. With 3/4" sides, and 7/32" (slightly thinner than 1/4") bottom and gussets, it is very stiff and strong, and only weighs 13 lbs. The 7/32" bottom can flex a bit in the middle, but should have no problem supporting the electronics, as well as heavier stuff near the edges.
If you can get some 1/4" and 3/4" plywood, I strongly suggest you build one similar to ours and see how you like it…you might be surprised how strong and light it is.
ill see what I can get…
im not very good with small objects and I tend to break things easily(which is why they call me gorrilla)
i was thinking about the dead axles when i made the decision to use 2x6’s that way they could be supported better without putting to much stress on the wood
i think i could combine the two designs, like keep the 2x6’s for the sides, but have the plwood for the ends and bottom, I like those steel L-brackets, they added lots of lateral stiffness
There is no need at all for the steel corner brackets if you use the triangle gusset plates on the top. All they do is add weight.
The 2x6 sides are way overkill, if you think you need some more strength at the axle attachment points, you could double the plywood at that area, but it really isn’t needed. The cantilevered axles are short, and if they are made of 1/2" bolts then they are very strong, and the nuts and washers used to attach them spread the load out over a large area of wood. Also birch plywood is harder and stronger (because it’s laminated from plies that go different directions) than a fir 2x6.
There is a lot of engineering thought behind the design we came up with…
the L-brackets are small, only two inches long and 1/2inch wide…
If we were gonig to use it for competition I would use your design but intstead of dead axles, i would use directly driven wheels so there ould be as little pressure on the shaft as possible,
i also think that its way overkill for just a demo-bot, but if we had to use wood next year, i know that it would be a very long decision on which way to do it,(probobly would end up a mixture of both)
could you list what you think are the pros and cons of both?
There is no need to have as little pressure on the shaft as possible, if you make the axle shaft strong and well supported. If the shaft is short and large diameter and well supported, it can take a lot of load!
could you list what you think are the pros and cons of both?
The neat thing about the wood chassis concept, is that you can build a couple of them, using different designs, for not much money. Then you can see how they work.
