I am sure this has been answered before but I could not find it. Buying the MK3 swerve module do we need the short falcon shafts or is that just for the MK2s?
You will if you don’t want to use motor spacers.
Edit: To clarify, if you use the motor spacers you won’t need to cut down your shafts, but if you decide that you don’t want to use the motor spacers for some reason, either in a bid to save on a little bit of weight or module height, then you’ll have to cut down the shafts by a quarter inch.
We 3D printed our own on our Ender Pro 3. Ours have held up fine throughout the entire season, as they have almost no load on them, so if you have access to a 3d printer, I think 3D printing is better than paying $100 plus shipping for the spacers, (but it’s understandable if you can’t). If anyone wants I can attach the CAD file I just don’t have access right now.
I was confused because the links says it is for the MK2. Why does the site not say it is for the MK3s as well?
Yeah, IIRC they were originally designed for use with the MK2s and Neos, but work just as well with the MK3s and Falcons so they were never redesigned.
Is the spacer required or optional, from what I have seen there is enough room for the regular shaft.
If you don’t want to cut your shafts down by a quarter inch, then yes, I believe the shaft will contact the spur gear coaxial with the smaller 15t bevel at some point in a full module rotation if it isn’t used.
Your options are:
cut down the motor shaft so it won’t interfere with the other gears
use the spacers or stand ins for the spacers
We used the spacers and it worked great. No complaints.
I highly recommend using the motor spacers with Falcons. Cutting the spline shaft down by 0.3" and still being able to retain a gear on the shaft is not trivial:
The Falcon short shaft is really designed for use with VersaPlanetary gearboxes and is a little too short to use with a normal Falcon pinion.