Accounting for excess in order for two objects to fit smoothly

I’m making a cylinder which fits together and I want it to be flush. I want both parts to slide into each other smoothly as it needs to be spring assisted too.
I’m new to CAD so I printed it and have found that when trying to put them together, they are extremely stiff and difficult to actually connect.

I’m assuming there must be a tool or something in Rhino that allows me to slightly reduce outside dimensions or something to account for the excess material causing this stiffness. I’m guessing the problem has occurred due to the plastic setting with a slight excess of a couple of mm. Is there anyway to reduce the outsides (but not the total object) as to achieve a perfect fit?

I apologise if this is difficult to understand, I most definitely need to touch up on my terminology. Thanks for your help!

(See below for visual representations)



This might work. You may need to experiment a bit so make copies of both parts so you can get back to your starting point…

Position the two pieces together in their fully interlocked position and scale the inner piece up very slightly in the x and y directions (boxedit with x and y set to centre and copy set to yes is good for this, because you can set very precise sizes). Then Boolean subtract the oversize inner from the outer. Use the result in conjunction with the original inner to make your parts.

You may find that the clearance between the fins and the clearance between the cylinders need to be adjusted separately because one is still tight while the other is loose. In this case, you would have to model a copy of the inner from scratch instead of scaling it.