We have seen different “add-on” amounts needed for 221 System sprockets and for Vex sprockets. It will depend on the design of the sprocket and the machining tolerances .035" is a little much as we saw a little cogging with new chains, but this amount has worn in nice and worked for our setup perfectly.
This setup also has interchangeable outer bearing blocks that allowed for experimenting with wheel drop on the same chassis. So chain length will vary slightly as the wheels are moved up or down for different drop amounts.
Be careful with chain in tube, as the centrally located rivet holes will interfere with the chains! You need to offset the rivet holes to match your chain locations to avoid the rivet bulbs interfering with the chains. We spot drilled the offset holes needed to integrate these new frame rails into an existing practice robot.