Best was to make a "slot cut"

[Martin01]

I am close to finishing rough framed interior walls, and even though plumbing is not started, I am starting to plan for the finishing of these interior walls (shiplap panels). I understand these should be cut to mimic the curvature of my 10" logs where the panels meet the exterior walls, then accept future board shrinkage and address that with caulk. OR, a "slot cut" can be made into the logs, a cut 3/4" wide and 1/2 inch deep. Then the board slides into this slot, and when it shrinks the shrinkage is not noticeable, it still appears snug to the log curvature and looks tight.

1) what is the best way to make this slot cut? Skill saw? Router? Multi tool? Then use a 3/4" chisel? I am interested in the most in control method that doesn't take forever... Do you put down a guide board to help hold the line? How do you create this slot cut in the hard to reach portion of the curvature, where the two logs meet? The world wide web has no videos I can find on this.

2) what is the best way to cut the shiplap board end with the proper arc so it mimics the log curvature. I can certainly create a template for marking, but then do people just use a jigsaw? Is there a different tool? My jigsaw lines always have more wobble than I like.

Thank you very much for any comments!

[Martin01]

Whoops... Should be titled, "Best Way to Make a "Slot Cut"?

[donjuedo]

I don't own one of these, yet, but would like to:

https://www.homedepot.com/p/Makita-18-Volt-LXT-Lithium-Ion-Cordless-Variable-Speed-Oscillating-Multi-Tool-Tool-Only-With-Blade-and-Accessory-Adapters-XMT03Z/205302496

It looks like it would be useful for defining the edge where the finished lumber slides into the log wall, and also where finish flooring meets a ridge pole support log.

[Mosseyme]

I cut slots in the rpsls for the flooring. Made first cut with the wide flat blade on a multi tool. First cut just lay the say blade on the subfloor, cut all the way around. Then use a piece of flooring for a spacer setting the blad in it and moving it around as you cut, then chisel it out. Worked very well.
For the wall I'm scribing the panels to fit the logs. Mark a rough shape cut with the jig saw then do it again and again. Until I get it close then use a sander to finish the shaping to fit.