Terrypin-not sure which you are asking about -the reaming or making a hole with walls. I will assume the latter. In scattering of menus in CURA:
>>In the upper Right is a toolbar with 3 small "bars". Click on the bars to expand the menu
>>in the lower right of that menu is a "button" that says "CUSTOM". Click this
>>A set of dropdowns with names like "Quality, Shell,Infill ......" will appear
>> Click on "SHELL"
>> You will see "Wall Line Count" as an option. Keep increasing this and use the "Preview of Cura to see the resulting walls. You need to pick on that gives you enough thickness to accept your threads. How thick is, of course, empirical---try about 10 for starters.

With all the menus, dropdowns, buttons, bars, right-clicks and everything else in modern software it is no wonder that takes a 3"thick manual to document it!

I hope this helps- I am learning a lot of this along with you!
Fritz