Mentors and Olson Routing Rings

Hello again, welcome to episode 2. I’m pumped! Last time I did my best to say hello and update you on the state of my “now.” This time I want to talk about mentors and molds.

Like you, along with the actual 1-on-1 mentors I’ve had, I’ve spent all my free (and non-free) time scouring every media format learning all things guitar. My first mentor was a World War 2 radio technician who had 10 years of amplifier repair work filling his shop and didn’t want to work on guitars, so he made me work on them. “Here kid, I have no time for these,” and he put three guitars on the bench. “Do you know how to do a setup?” Reuben was my first mentor; his shop was my second.

In between the on-the-bench lessons with Reuben I scoured the factory dealer brochures and spec sheets on his shelves, then his books, then the guitar magazines for sale up by the front counter. At 13 I worked in a place that had Fender and Martin factory catalogues and spec sheets! I felt cool and thought I was fancy.

Whether they know it or not, those authors and video personalities are, and always have been, my additional mentors. Those 35 years of mentors from all angles — and you, Looth Group Members — are the reason I’m proud to say I have finally achieved a level that is “moderately above mediocre.” Hurray. Thanks all!

When LMI closed in 2024, their YouTube page disappeared. The most important video on that channel was the early-90s Small Shop Production Video: Jim Olson, Kent Everett and John Greven making the dream of being a solo guitar maker possible — one-man shops each building 50–60+ instruments a year. The first segment was Jim Olson showing a slide show of his entire build process. It was my heaven. My bible. My roadmap. I wore out three VHS cassettes and two DVDs of that Healdsburg builders’ talk.

Years later I went from a fan of Jim’s work to being one of those occasional shop helpers. He became an actual mentor. What I want to share today is the Olson body molds and routing rings I first found on that Small Shop Production video.

Here’s this week’s key disclaimer: I have imprinted on the Olson (Minnesota) style of guitar building. You won’t get a Martin, Gibson, or any other maker’s perspective from me. With that in mind, let’s jump into the cool stuff!

I use Jim’s mold and rings design for holding and fitting bent sides. With these same molds I’ll block, profile sides (and blocks) with a router to near-final dimension, glue and radius kerfing to final dimension, and glue on my tops. All because I hate driving the bus. I hate it!

Driving the bus is when you use a radiused sanding dish to profile the sides and radius the kerfing — turning a dish as big as a vintage bus’s steering wheel until every surface is profiled. It takes forever. The MDF flexes, the bolt pressure won’t stay consistent, and your arms hurt. Consistency was impossible.

I considered mounting a dish to a motor — a 24″ MDF disc spinning at speed. Dish deflection, paper changes, a giant box to house it… Nope. No spinning wobbly death machine in my shop!

So what do I do? I want perfect shapes every time. Enter the LMI Small Shop Production video and Jim Olson’s mold-and-rings design, which uses a mold plus three specialty-surfaced rings.

Use ¾″ routed plywood rings — I only use imported “cabinet grade” plywood with 11+ laminates; it’s expensive but won’t warp if it gets wet. The finished guitar dimension is on the inside of the mold ring with a 1⅞″ border. Stack 6–8 rings per mold over one solid base sheet. I keep two heavy molds per body shape (a top mold and a back mold) plus a short, dividable 4–5 ring version I use when gluing on the back.

I use a 15′ back radius, so the back ring is radiused (arched/convex) at 15′ and profiled for the ¾″ taper from heel block to neck block. The part of the ring over the heel block is 1⅜″ thick; over the neck block it’s ⅝″ thick.

To be fancy, I build the fretboard-extension fall-away into my tops. From the leading edge of the sound hole to the neck block there’s a built-in taper that forces the fretboard extension into an up-angle and, done correctly, eliminates fall-away over the body. So my top ring isn’t 100% flat — it has that built-in down-taper ramp from the soundhole edge to the body edge at the neck block.

This inner mold ring is radiused at 15′ but dished (concave) and thicknessed to match the back’s taper — this time in reverse of the back arch ring. It’s ¾″ thicker at the neck block and thinner at the tail block.

Bend your sides ⅛″–¼″ strong on the bass side only. My guitars are built with a true flat-top, Olson style — zero arch, dome, or radius on the tops. Some builders use a 25–40′ top radius; mine have zero, making a real flat-top.

The top edge of my sides is trued on a jointer before bending. I trace a template with the ¾″ side-back taper drawn in, mark the final profile line on the inside surface, and at the bandsaw I leave the line plus an extra ⅛″–¼″. Pay attention to inner vs. outer surfaces when prepping to bend.

I mark the center of the waist on the outer surface with a fabric tape, square it off the jointed edge, and place the sides into the bender along the guard — the flat treble side rides the flat support of the jig as a straight edge to help alignment.

• After bending, clamp side 1 in, bass side up, with sticks to hold. Start clamping at the waist.
• Use a 90° square at the mold’s center lines (neck block, tail block, or cutaway termination) to mark a square line from the base plate.
• Remove side 1 and bandsaw the bulk off, then sand to your lines in stages, checking fit to the marked center line.
• Insert side 2, bass side up, and mark to fit. Remove, bandsaw the bulk, and sand to your lines — leaving the line plus ⅛″ on each end.
• Re-clamp side 1 at the waist. Fit side 2 to side 1 with the sander, clamping side 2 into the mold at the waist as you perfect the fit.

• Add wax paper behind the butt joint of the sides at the neck and tail block.
• Add spreaders to the upper and lower bouts, clamping the sides into the mold.
• Add a clamp block that meets the full height of the side and is ½″ wider than the tail block.
• Make the neck block to final dimension + ¼″ height; tail block to final shape + ⅛″ height.
• Mark the center of the blocks and glue in using the centerline of the mold — not the fitted side butt-joint line. Unclamp when dry.

Use an extended router base (make a long-board base) and a dovetail bit with an undersized guide bearing — smaller than the bottom flair of the bit. This lets the bit’s angle absorb the radius of the back ring and the fall-away of the top ring. A regular pattern bit with a matching bearing leaves a gap; the dovetail bit with the undersized bearing flips that gap and can cut all the way through.

• With the back ring on top of the mold, climb-cut (route counter-clockwise) the back arch to final dimension + 1/16″ into the side, using the inside profile line from your layout. You may need one more mold ring depending on bit length.
• Be sure the bit routes the sides at all points.
• Clean excess with a finger plane as needed.

• Remove the back ring and add/remove 1–2 rings — just enough so your kerfing clamps fit all the way around.
• Kerf the back, leaving the kerfing just above the side (the 1/16″ left proud in profiling helps when radiusing). Let dry.
• Replace the ring(s) and back ring. Route the kerfing to final depth, holding the router to the radiused back ring so it stays angled. Keep your hands wide, climb-cut, and move slowly so the bit tickles each nib off. Do not go fast — walk, don’t run.
• Be sure the bit routes the sides at all points.

When you get used to leaving the right amount of kerfing proud of the side, the top of the kerfing curls off. It’s cute, and kinda fun!

• Remove the sides with kerfed/radiused back and insert the center-radiused profile ring (or move to the top mold if you built more than one). Use the top routing ring and maybe an extra mold ring depending on bit length.
• Insert the sides with the kerfed/radiused back facing down, tops facing up. Add spreaders.
• Set the bit to kiss the tail block. Route counter-clockwise, taking multiple passes over the neck block as needed. Keep your hands wide to keep the router balanced and flat.
• Be sure the bit routes the sides at all points.

• Remove the top ring and 1–2 rings — just enough so your kerfing clamps fit above the mold rings all the way around.
• Kerf the top, leaving the kerfing just above the side. Let dry.
• Replace the ring(s) and top ring. Route the kerfing to final depth against the radiused top ring. Climb-cut and move slowly so the bit tickles each nib off. Do not go fast — walk, don’t run.
• Be sure the bit routes the sides at all points.

Sweet — now your sides are done! You have fitted, blocked, profiled, kerfed, and radiused sides that come out perfect every time, without having to drive the bus. Thanks Jim!

Have a great week. Ask any questions you might have, and see you next week!

Cheers,
Todd