Official Luthiers Forum!

Why can't we build straight of the plan and pre-shape the sides and carefully align the kerfed lining so they can be scraped or sanded down to the side? I really dislike the cost "yes I'm poor" of dishes and would rather not use them. I don't want to make them either. Seems like guitars were built just fine before this invention. It may be an easier procedure once you have them and have the go-bar deck and all. The plans come with the side shapes but nobody uses that.

My next build I'm not going to use the dishes I have and see how it goes. That goes for my go-bar deck as well. That thing takes up too much valuable shop space.

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

You can always build with the rims flat with radiused braces. If you want the back radiused you can profile the sides without a dish if you have a good template for the sides and are careful to bend at the right location. I do have dishes but I also build by making a radiused sanding bar to clean up, especially the back side of the heel block. I make radiused bars from scrap. They are handy to radius the braces and use can use one as a caul while gluing in braces.

I use the bar when I am working on a solera, then the dish is too cumbersome. I have really good templates for the sides and the Spanish heel slipper. I use the bar to clean up the back side of the rims and the blocks.

_________________
http://www.Harvestmoonguitars.com

I used a radiused sanding bar for the top because I didn't want to purchase a second dish. I pre-shaped the braces to plan with a hand plane, very enjoyable and dust free. and forced the top to that curvature.

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

Sounds right. No need for a dish to build, although working with a mold they are really handy. For example you can use a mold on a radius dish to make your own radiused side templates. Sometimes one might want to build without a plan.

_________________
http://www.Harvestmoonguitars.com

No plan? Someday.

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

The Stew Mac website has instructions for assembling their kit guitars that doesn't employ the use of a radiused dish. I
remember seeing it a few years back, Probably still there I'd imagine. You might glean an idea or two from it....

I have it printed and bound in my bookshelf.

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

The late Ken Cierpilowski , who was a contributor here, Made kits and tools for which the instructions are being maintained on John Parchem's website. There is an alternative to radiused dishes described there, hopefully John won't mind me providing the link.....https://www.harvestmoonguitars.com/kenn ... rtool.html.
Ken used 3 x 5 cards. I used my business cards post-retirement.

I've never used a radius dish and have no plans to ever use one. Of course you are correct, guitars have been build on open work boards for centuries. The radius dish is really more of a assembly line factory tool that has been adopted by small shop luthiers to enhance their style of building. But it doesn't mean it needs to be your style of building. Millard, Gurian , Sexauer and many other well known luthiers don't use radius dishes.

What a great idea but I assumed that if the braces are shaped correctly the the soundboard would automatically take the shape if glued flat. I'll try this method on guitar 2

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

OP: read up on Ken's technique of a cascade of cards to emulate a radius dish under a brace. I've used it, with care it works well and it's dirt cheap and easy to store.

_________________
Peter Havriluk

The outside mold+radius dish style is certainly not the only way to do it, especially if you're not trying to make a living at it. My style uses no workboards at all, but is pretty slow, optimized for flexibility and minimal space consumption. Radius braces with plane and glue with cam clamps. Plane the the sides straight, bend on hot pipe, and glue them to the tail block (and cutaway corner block, if present). Then glue that whole unit to the soundboard with dentellones. Plane the back rim pretty close to what I want, add linings, and drag on flat sandpaper, tilting left and right to create a cylindrical radius. Glue the back on with spool clamps, with the neck on so you can check the angle and crank it forward or back as necessary to get it just right. Dentellones should also be done with the neck on. Note the shim under the nut area to coax the neck angle into the right area (and the planes, which are acting as weights). I build integral necks, but this approach would work just as well if it were detachable.

Dennis, I love this method. I'm in no hurry to spit out guitars and would prefer less crap in my shop.

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

It is great to get the link out.
Ken's spouse asked me to save the information and make sure it was avalable. I have this link on Ken's old forum that I also maintain as well.

_________________
http://www.Harvestmoonguitars.com

Kens method is incredibly elegant in it's simplicity. Keep it simple. That's fantastic.

The method outlined by the OP is what Martin did until their retooling in the early 1990's. I have used it for the last 40 years, with no desire to change.
I glue the kerfing on the sides a bit proud of the edge, and shape it with a block plane and sanding block. I use a simple arching template to check the angle of the kerfing around the back. Kerfing around the top is planed/sanded flat.

Sent from my SM-G950U1 using Tapatalk

_________________
John

This really is an important point that I think gets lost when people are trying to get started. It doesn’t just apply to radius dishes. It is true for molds and dozens of other tools or operations. There are tons of ways to make a guitar. Some work better for others and not so well for some people. I feel like it mostly comes down to what the individual is comfortable with and has access to. That includes tool skills, tools available, space, production goals. . .

You can pick and choose various methods for various operations to suit your situation. The only caveat is that you have to understand how certain operations work with certain others to achieve the geometry you want.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Buy a dish? I think the ones I took with me when I left Greenridge were both shopmade. The guys had just done a run of a dozen or so before I arrived, and I took the last 15' and 28' on departure. I am not sure whether Mr. Paulick's method was employed, but it appears to work just fine. There are a half dozen or so other YouTube vids on the same topic.

https://youtu.be/tvGemvizrz4?t=29

We certainly were more jigged up with radius dishes, etc. than pre-dish Martin, but then again, we never had to have boxes of bridges of different thicknesses to compensate for variation in body geometry. Not sure if Martin went to radius dishes to fix that problem, but if so, it does not appear to have taken.

_________________
For the times they are a changin'

- Bob Dylan

Of course there are many ways to skin a cat......

I use the dome dish for the back radius on my guitars and am very happy with the results. Before that I used a different method,but never was happy with the results.

As far as go-bars taking up space, I find the opposite to be true.
I don't have a seperate go bar deck, I simply use the shelf above my bench as the "lid" of the "deck"


My go- bars fit in a very small space on the shelf.
By contrast the amount of spool or cam clamps needed for that operation would take up more space than that...

For me the "discovery" of the go-bar system was one of those things that made my building vastly more efficient .

Another way to make a "radius" dish is to glue small blocks around the edge of a thin circular piece of plywood and screw it down in the center to pull it into a "radius" ( more likely a spline curve shape -close enough). If your bench is wide enough you could screw it down to the bench surface when you need it and unscrew it when you don't.

At my previous house, I used the low basement ceiling above a bench but I decided to build one when I got into my new house. I think I'll put up a piece of plywood and use my tablesaw in the future. My TS gets more use as an assembly bench anyway. I prefer my bandsaw for most things.
As for home-made dishes, I built one and it's certainly good enough for dialing in the rims, I wouldn't use it for shaping ir clamping the braces. The spine thing bugs me, it's practically a cone shape. Maybe before I start my second guitar I'll make a better one with a router.

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

The spline curve shouldn’t bother you. Look at the actual difference in the line formed between a sphere and a spline curve at this scale. It is minuscule. Remember the actual radius numbers people use is fairly arbitrary; some use 27 some 28, both make guitars. Remember we are dealing with wood that springs back to some degree and moves with humidity. Sometimes we put too much emphasis on precision here. I’m not saying do sloppy work. We have to accept that if we glue braces to a top in a perfectly spherical dome, we still won’t have a perfectly spherical top. The wood will change a bit and it will do so differently across the grain than it does along the grain. That alone is more dramatic than the difference between a spline curve and a sphere.

How many guitars have been made using the C&N book. That book shows you how to use a spline curve to lay out your braces. I used an adjustable dish that created a spline curve (using the offset numbers in that book) until I made a motorized sanding dish and MDF dishes this year. I don’t expect to notice any difference in the final product.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

You're right Bryan, I'm overthinking this.i make splined dishes in my drumsander.

_________________
Hutch

Get the heck off the couch and go build a guitar!!!!

Yep. And even if the soundboard is constructed perfectly spherical and maintained in exactly the same humidity, it will be pulled into an S-curve shape once you put strings on it (unless it's too stiff to sound good). I shape my braces to counteract that a bit. Plane them flatter in the bridge area and more curved in the upper bout. Mark a straight line on the brace to use as a visual reference when planing, and use the saggita formula to get the approximate spherical radius http://liutaiomottola.com/formulae/sag.htm

If you shape the bottom of a brace perfectly to match a perfectly spherical dish, that curve will not actually match the curve of the inside of the top plate pressed into the dish. The 2.5ish mm thickness of the plate will offset the curve needed on the inside. We ignore that difference all the time; that is probably around the type of difference a spline curve has compared to a sphere on this context.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.