How To Build An Acoustic Guitar Episode 12 (Radius The Sides) 

We now sell hand selected and resawn Tonewoods on our website! Each piece was found by Chris Alvarado, and almost always has a story to go along with it. Go check out the selection at www.driftwoodguitars.com/tonewood

I believe the easy way to reduce the inside of the bevel is to have Matt do it.

“Matt Has Questions” should be called “Matt’s Mysterious, Mythical Questions”, because we never know what he’s going to ask; then Chris usually gives him a look like, “thanks, bud, never thought of that”, but then “Charlie’s Woodshed” hours usually align with their work hours, so they have a cute little distraction - keep having Charlie on your channel! He’s so adorable and an entertaining part that’s added to your builds!

It's craftsmanship when you take the time to finish off the bottom of the armrest that nobody will ever see..thanks!

It’s already been mentioned but I’ll second it. Find a used electric potters wheel and convert it to do your radius sanding. It couldn’t involve more than taking the wheel’s top plate and drilling some holes to fasten to the underside of your radius board. You might have to shim the radius board so it clears the rim of the wheel bowl. You could even install threaded inserts in the bottom of the radius board so it would properly mate with the drilled holes in the top plate. The advantage of the potters wheel is you can dial in the speed to your liking.

"Matt has Questions" needs to be highlighted from time to time! Sort of a shout out to Monty Python's, "And now for something completely different!" 😏 Absolutely love this series!! Great job guys!! Thank you both so much for sharing so much of your time and wisdom with us! 🙏

Thanks, I've learned so much. Keep it up!

I think the radius in the back is also there to work as kind of a parabolic mirror, so that the soundwaves are guided to the soundhole, thus helping you to get more sound. Also, maybe an easier way to do that thing with the arm bevel could be to use the CNC machine. When cutting, only cut all the way through on one side, then flip the whole board around and do sort of a radius cut on the other side. It should only need a little cleanup afterwards. Loving this series and looking forward for what's to come.

This series keeps getting better and better. Keep up the great work!

Good video. Good info! Looking forward to the next one!

Another great episode...thanks guys. Can't wait Ep.13 (Cheers and "see you" there).

Thanks 🙏. We all have our own ways. Thank you so much for sharing. very nice work!!

Amazing work

Looks good mate. That step is truly a pain!!

It's enjoyable and inspiring to watch and learn from a real craftsman. Your thoughts and techniques are well proven in the final product. The proof is in the pudding as they say. Thanks for taking the time and to share your skills.

Great tip on beveling the tail block. Makes sense and it is an area that the geometry challenges me, both top and back. Thanks!

Thanks a lot for sharing all you tricks and experiences, I don't know if I'll ever build an acoustic guitar but even so it's so great to watch all your videos. Amazing radius !

Drawings worked perfectly for me. Thank you Matt for asking the question. Thank you so much for these videos!!! So valuable. You guys are contributing to the on-line luthier community in such a meaningful way. (entertaining too!)

I'm loving this channel. Great work guys. I will be starting my first acoustic soon, and this channel is gold! Thanks 👍🏻

I really appreciate the way you always keep the way the top resonates in mind while you take the preliminary steps. Your attention to detail will ensure the top resonates equally across the entire lower bout.

I'm glad Matt has questions... Because I have very similar ones! Just want to say thanks again for sharing your process with all of us out here in Neverland. It's been great to hear your detailed insight during the building process.

I had a dog growing up named Charlie that looked EXACTLY like your Charlie. Also, the editing is top knotch - each video looks better than the last!

Chris and Matt, Thanks so much for doing this build step-by-step. I’ve never made a guitar before so I’m just working on getting set up first (which is taking forever!). I know I’ll have problems but I’m confident now that I’ll make fewer mistakes having watched your videos. Much appreciated!

Thank you soo much Chris for this vid, to me it is worth it's weight in gold! I'm on my first scratch build after 2 kits, and the advice about keeping the upper bout area of the soundboard perfectly flat is a heaping help. I've seen many 'how to' vids but this one should take the nth prize because no one else is explaining this. Mark

Just the right amount of goof and goodies. Really love this build series. I am building a parlor sized guitar (my 2nd acoustic build). The relatively small body size really made huge difference when I radiused the top side of the body too much on the neck block end.. The exact thing you drew up in the "Matt Has Questions" section happened to me. I didn't notice it until the body was all glued up. My solution was to essentially radius the underside of the fingerboard to match the top radius. It works, but a lot of work.

Have to disagree with you. I'm a professional draftsman, and I have to say, your drawings, especially done upsidedown, are really good. It's pretty clear being able to draw is another of your talents. Well done.

I watch tons of RU-vid videos and this Channel is the only one I’ve ever subscribed to. It’s amazing!

About to start my first build, and these videos are massively valuable… aspirational, educational and a little fear inducing to a first timer! Thank you

Hi Guys. Long time viewer, first time commenter here. I am sorry to be pedantic about geometry terms, but I'm fairly certain that the beach ball metaphor at the beginning is a little flawed. I believe that a 15' radius beach ball would be 30' in diameter and the 30' radius would be 60' in diameter. Anyway, love the channel and what you do there. Keep it up.

Matt's not the only one that had questions about the upper bout. I've been struggling with that question, which others that I have seen only hinted at or did the flat sanding but didn't explain. So thanks for laying it all out. My current build will be better for it, plus I like the solid kerfing tip very much.

Love this series!

remember chris, dremel and carbide bit. as always i enjoy watching your process of building these guitars, as well as other shenanigans you guys get into.

Thank you so much for this series. I'm using it to build my first guitar! I got my materials last weekend, got the top glued together, and now figuring out the best way to thickness by hand. Wish me luck!

One trick that helped me a lot, was instead of moving the guitar over the radius dish, we mounted handles to the back of the radius dish, that way you can use the weight of the radius dish (the dish we had was aluminum which was enough weight) to apply downward pressure while sanding, and all I had to do was twist it back and forth. Saved so much time, as well as wear and tear on my back and shoulders.

I've always believed that an all "solid" wood was superior. Now I can see that laminate sides make more sense. This has changed my perspective on building, thanks.

Watching a year later, and getting my mind blown. Your videos are dynamite! Eyeing retirement, and building a high performance guitar is at the top of my list of adventures... Was curious to know if you have any thoughts on elevated necks, or a cantilevered necks. You have dialed in your system and are achieving great results, so I am not suggesting you changing your method... but your opinion may be interesting to other followers. I played a beautiful classical guitar a while back with an elevated neck, and it was nice for getting at the higher frets - and I imagine it may be advantageous in connecting fretboard to soundboard. Thanks for producing these vids. Totally enjoying and absorbing them. It is easy to see how subscriptions have grown from 18 K to nearly 50 thousand - it's almost like being in the shop with you guys, and after the shoot you plan to pour a drink, sit down with viewers to play some Blues in E. Congratulations!

Hey, at gibson, to get the fretboard section flat after gluing on the top, we just used a flat piece of wood between the sander and sandpaper. We radiused the whole top, glued it on, then sanded the top flat where the FB meets the top so you don't ski jump. No fancy tools needed (;

Cool series its been a pleasure to watch you craft this guitar. Since you asked... it would be a lot easier to finish /reduce the size and weight of that arm bevel backer prior to install. I am not a guitar builder but as a professional craftsman I highly recommend you put a 2X72" belt grinder or similar in your shop. This allows you to have multiple contact wheels for various radius' and the thin belt is great for contouring tight/awkward access spots. Would be a dream for cutting the arm bevel contour in the sides, neck work, etc.. (And pre scalloping bracing sshhh I won't tell anyone)

Yep I ran into this problem as well. I ended up tapering the fretboard in the area that meets the top to compensate. Way better to have a flat surface.

I'm following this build numerically to follow its true progress. And she's looking really good 🙂 BUT a quick word!! Please rest your plain on its side to protect the blade!

I had a thought that could help you when shaping the radius into the sides, If your dished sandpaper is level accross the top and your guitar is dimensionally square in the jig, you could just slap a level on it to make sure it’s sanding evenly. Measuring it all the way round to check its going even has got to be fairly slow, obviously still need to do that to make sure it’s perfect but you’d be able to quickly get a lot closer to finished before having to stop and measure. I have considered the fact that you probably know from experience weather it’s even or not from feel but still, and maybe for someone who’s less experience could speed things up. I try to find little quick cheats like this for my sanding projects and stuff just to speed up getting to the fine last bit

You can use a Dremel with a sanding bit to clean up the inside of the arm bevels during that side radius process.

Loving the series thank you very much. Like the 45 tail block makes sense. My first solo build I finished early this year I put a 25 radius on top and found that i could radius the sides and it didn’t touch the neck block top. Worked out well so might stick with that for now but super excited about arm/back bevels and the laminate sides. Why couldn’t you chamfer and clean up most of the arm bevel before you glue it in? One small vid that would be interesting and no one seems to cover is labels for the inside! What paper, glue & software you use ?

Jesus! It takes you 3,000 years to build a guitar! I don't think I can wait that long!

Great upper body workout- if it doesn't kill ya! I would call this method, with the radius dish screwed to the bench, "pushing the bus". I always radius the sides before installing the linings. Then glue the linings in slightly proud, and radius-sand again. Sounds like extra work, but it goes a lot more quickly, breaking it into two stages. That way, the linings keep to a consistent width. However, you will need to make a pattern and bandsaw your solid linings to follow the radius before you bend them. If you're lucky enough to find a used electric potter's wheel, you can easily modify it to do all your bus driving (or bus pushing) for you. By the way, the best radius dishes made (in my opinion) are the ones made by Canadian Luthier Supply, sold by Veritas Tools. They are flat on the bottom, perfectly radiused, and dimensionally stable, because they are made with 1 1/2" thick MDF. They cost about $70 each.

Great video, l am really enjoying following the build, just a couple info things to mention, It will require a 30 ft. dia. beach ball to imprint the 15 ft. radius and a 60 ft. dia. beach ball to imprint the 30 ft. radius. I also was wondering if you considered using the CNC to rough in the radius of the bevel block before gluing in place. Thanks for sharing.

Hey.. no more jump-cutting! Hooray for you guys...was I right about that? It doesn't matter, I don't need to be right. Your guitars are really beautiful and I can now see why as I watch you make them. I will never be able to afford one sadly but hey...

Chris, why not do a lot of your internal rough wood removal on the basswood before you glue it in place ? The spindle sander would remove a lot of the extra wood quickly. Love the videos,the three thousand year old spruce is amazing. Definitely would be my first choice. Don't feel too bad, I'm up here in MA and the next couple of days are supposed to be in the high nineties. Already have the first day of Fall marked off on my calendar. lol. I'm a New Englander, what can I say.

When you voiced the top I thought "hey, were almost done!"... That feels like 10 years ago.

I’m loving this series, you’re a real thoughtful luthier. I do wonder, however, if radiusing the top to “strengthen” it, actually stiffens it and blocks out lower frequency vibrations? I wonder if you kept the top flat, how the tone would change?

Hey y'all! Don't know why it took me so long to notice, but there's another pair of guitar builders here on YT named Matt and Chris. If you haven't checked out Texas Toast guitars yet, be sure to do so! They only build electric guitars, but they do it their way just as you do!

A rotary table to spin the radius while you hold the guitar body would make shorter work of it. I like your series.

you can get a drum sander that fits in your drill that you could sand that fairly easy...I have a few in my toolbox of different sizes

I’ve often wondered if one of the special ingredients to a hand made instrument was the sanding that creates vibration in the woods. There’s weeks and months of working the wood, sanding, then resting and settling. Working, and sanding and relaxing. Could this help create more settled and relaxed and ultimately more RESONANT instrument again ultimately making the instrument, be it a guitar or a viola more satisfying to the ears and FEEL to the player. I want to think so. I have build a couple electric guitars and it’s like they need a year plus of playing, humidity changes with the seasons to be right.

Seems like a set of hook knives for spoon making or cup/bowl carving tools would work well on that bevel.

If you're pre-making the arm bevel pieces with your CNC machine you could actually pre-shape the bevel AND pre-shape a complementary clamping caul.

on your attn to detail on the inside, i think it would affect the sound if you didn't do all of that. In building speaker cabinets, you always want smooth transitions between your inner structure because it can affect how the tone comes out of the box. There's isn't a whole lot of difference in thought at least at how the guitar body acts as a speaker box to tune and magnify the sound. i think that's why your guitars are so resonant and rich sounding... all the small details. good job!

Me thinks an easier way to do the arm bevel is pairing across the grain with a gouge, or using a Scorp or hook knife. If pairing, first use finger plane or a knife to knock off the far edge, relieving it so it doesn’t chip out the wood as the gouge finishes the cut. Relieve it 2/3 of the way, carefully pair down to that level with perhaps a 10 mm no. 8 gouge, then cut the relief this time going down to final depth, and finish pairing. Sand to remove beaver marks

I think that radiusing and cleaning the inside of the bevel might still affect the sound. It makes it lighter, and lighter braces and blocks usually allow an instrument to sound better, at least in theory.

Very cool. Do you need to make sure the flat section of the top is perpendicular to the side where the neck joins the body?

Nice, on that inside piece for the bevel edge could you shape it before you glue it in?

I enjoy your videos. You both do a great job but man-o-man, I do not like the heat. The pumpkin coffee joke made me laugh, but I won't be retiring and moving to Florida any time soon. Keep up the good work and have a great day. Lou

Really enjoying this series. Do you usually wear a respirator/mask when doing a lot of sanding? I have read it is a good idea. If not, what is your thought process there?

i only have 3 words for this video....SHAKE AND BAKE!!!

3d CNC that piece prior to gluing @9:23 side clamp and take some passes that your thumb thing would take and make 20 of them in a run

This comment pertains to the voicing episode, just thought you were more likely to see it on the newer video. You mentioned how the different sides of the voicing affected either the bass or treble (super interesting, did not know that). So do you think it would make a difference to use different woods for each side? A wood with a higher tonal vibration for the treble side, and a lower vibration for the bass side? Also, could you use bone or antler?

Another great video. Regarding your flat tops: Do you shoot for perfect neck angle, bridge height/saddle height, and zero radius "flat" upper bout so that the fret board doesn't fall away toward the sound hole at all? I'm not speaking to the 14th fret hump necessarily.....but do you prefer a little fall away?

Have you considered using a rotary tool like a Dremel (or something larger) with a reaming or sanding bit? That would allow you to "carve" that inside edge down by hand (with a lot of control), but much faster. Having watched further, your end result is very nice looking, but instead of a convex edge (bowing out into the body), the multi-tool method would allow you to make it convex. Perhaps not practical or desirable, just thinking out loud.

I’m no rocket surgeon, but would’nt a 30ft diameter beach ball leave a 15ft radius footprint? Btw. Love The content on this channel

On your arm rest bevel I would use a drum sander on my hand drill. I did top radius already , can I flaten the front part of my sides or is it to late. It's only my 2nd guitar! Watch RU-vid like yours Not my top is a 45' raduis Lookingbfor your recommendations

Could you do the radius on the bottom of the armrest prior to gluing it in? Since you do that step while the top is still flat it shouldn't be too hard to hold

Could you do the 15' & 35' radius on the CNC , at least to rough it in with just the finishing on the dome by hand ???

For getting rid of the hard edge on the arm bevel, is there anyway to do it before you glue it in?

I'm in DE and when ever I am outside for more than 5 minutes I am soaking wet in sweat. I need some serious rain storms, I actually might go outside.

Most guitar builders cut the bridge plate so the grain is perpendicular to the top’s grain. But then the bridge pin holes end up being drilled parallel to the bridge plate’s grain, and it seems like that would weaken it. Would cutting the bridge plate at a 45-degree angle to the top’s grain work?

Can you use a dremmel tool to shape the inside of that arm bevel?

Hi Chris, I believe I saw you put an angle on where the neckblock meets the fingerboard extension of the neck block in an earlier episode of this build. When answering Matt's question on the bevel on the top you did not bring this detail up in your explanation. Might be I missed something but the fingerboard extension part of the neck block does not look to be at a 90° angle to the neckblock to me.

Can you knock some of the material off the piece for the contour before you glue it in? If not how about a Dremel type tool to get most of it off before you use the thumb plane?

I have a CNC and am trying to make my own radius dishes but I'm struggling with the dimensions. For your 15 and 30 foot radius dishes, what are the diameters and cm / mm drop in the center? Is there a better place to ask for this info?

Could you radius the inside of the arm bevel with a router, or the CNC, before you glue it onto the guitar assembly? Or would that affect the assembly process too much?

A suggestion for the inside convex surface, you can make a tool using a wood dowel lathed/turned to have an hourglass shaped profile. You can use adhesive stick on sandpaper on that profile if it's got a piece of all thread up the middle axis so it can be chucked in a drill for use on the feature in your guitar. Another option would be to reshape a scraper with the arced profile you want to make on that inside reinforcement.

You could setup your cnc cutter to sand depth?

To knock down your bevel on the inside might I suggest clamping a sheet of .03 Brass, or whatever sheet to the side, and using progressive grits on a Rotary Sanding drum. The metal sheet will take away the fear of gouging the side, while making your job a WHOLE lot less SWEATY!!!! Just Sayin' Gb g

Since you are making the rims flat on the the neck block of the intersection of the x brace and radiused on the tail block side, have you considered only radiusing one side of your x brace and leaving the other side flat?

What about using a small spoke shave to get that inside radius?

MDF board is dead nuts flat too but it does have a little weight to it.

Not monotonous at all. I thoroughly enjoyed Avery bit of that vid. Thanks for sweating it out for us 😅!!!

To remove the inside of the arm bevel, maybe a wood rasp or a spokeshave might make the job faster, but both are still hand tools.

Would you still call it kerfing if it's solid all the way around?

What about a 1/2" with air powered sander. You could use spring steel inside to protect from accidentally scanning the rosewood

an easier way for reducing down the inside of the arm bevel... maybe a modified spoke shave with one are reduced in size, so as to stop it bashing on the inside of the sides?

Where the hell do you get a 15ft beach ball never mind a 30ft one I think we need to see them you must have mighty lungs old chap wow! Love from London England 😂👍

I would per shape it to close to its shape before gluing it in, is I want it to fade completely to the side. This will leave very little hand sanding and completely eliminate the plane.

On this episode of “this old guitar” hosted by Chris Villa-rado. 😂

Do you make or buy your radius decks?

what about a dremil tool to shave out the inside of the bevel?

Can u radius the back and top without a radius dish

Get you a Stanley No. 113 radius plane for the arm bevel

Amazing guitars, unfortunately totally out of my reach. Are you considering production of chipper guitars, sort of what PRS is doing, several levels of price and quality, but all good within certain price range?

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