designing a sprocket in Catia isn't trivial AFAIK.
I never tried Catia to be honest, but designing a sprocket in any CAD program is a pain
to my experience...
basically there are two approaches, a substractive and an additive way of making one.
I prefere the substractive way, since it's easier in most programs I used so far.
here it goes:
draw a circle, and extrude it to the needed width (inner chainwidth - 0.2mm)
any large enough radius will do for now (say 30cm diameter // 15cm radius)
now draw another much smaller circle, matching the diameter of the chain rollers (plus again a bit 0.1mm should do)
clone that second circle on it's origin and enlarge it's diameter to your needed chain pitch (say 12.7mm for a #40 chain)
group the two
Now comes the tricky part..
nearly every CAD tool has a script to multiply and align items along a line (or circle)
you want to use that in a way that the first and last circle are touching each other and the total amount of clones matches your toothcount
(could be calculated.. but is faster done by hand IMHO)
remeber the circle the smaller ones are aligned to (keep a backup)
got it.. now substract (bool) ALL the smaller circles (the ones NOT touching each other)
from your raw extrusion...
take the backup from above and bool combine it with the raw extrusion and you should be left with a sprocket that's missing it's tips..
build one tip (a rounded v-shape roughly the height of half a roller), and clone it to the other teeth (again, use the script)
fix the holes, solidify (and unify) the tips with your raw extrusion,
and all that's left to do for a nice sprocket is chamfering the edges a tiny bit (0.5mm)
drill your holes, and the center bore and you're done.
Not good enough to have it machined.. (not nearly good enough!!)
but good enough to match it up with a premade rollerchain, and for a rendering
to measure it's diameter and to allow it to 'pseudo mechanically interact'
if you use a bike engine, then it's indeed good enough to use the bikes sprocket ratios for a good start.
ideally a sprocket tooth looks like this:
Anyways:
Since the wheels on a kart are likely much smaller than a typical bike wheel, the torque will raise, and the top speed will drop according to your needs;
or at least very close to your needs; especially an engine with a gear box will not have any troubles with the additional weight of a kart.
for a much better staement what ratio you should try, we need engine specs, kart specs and wheel specs (power, weight, diameter etc.pp)
'sid
