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Rubbertoe
11-25-2009, 11:57 AM
I've been doing some reading here in the Luthier's Lounge and have come across a few mentions of creating various radiuses of soundboard (25', 18', etc).
I've tried to do some googling on this subject but have only found fuzzy answers.
How does one radius a soundboard? Is this done in the clamping/go-barring stage? I ran across a few sites that say the soundboard is placed on a concave base plate of a go-bar deck but there weren't any other details other than that.
Do the tone bars have to be shaped to accomodate the radius of the soundboard (or will this occur naturally under the pressure of the go-bars)? And after the glue on the tone bars has dried how does the soundboard keep it's radius?

Moore Bettah Ukuleles
11-25-2009, 12:54 PM
Yes to all of your questions. Keep in mind that when you are beginning a new craft everything is fuzzy at the start. Even the clearest information doesn't make sense until you've got some experience down. You're not supposed to learn everything at once. One source is not going to give you all the information you seek but rather will be found in small increments here and there.Comprehension doesn't occur until you get you hands on the materials and practice the procedures for a while. It's part of the journey.

A radius dish or board is used for building and bracing the tops and backs. I believe I use 25' for the tops and 15' for the backs. Braces are sanded to the curve of the radius you want. Your glued-up sides (with kerfing attached) are also sanded in a radius dish. This is what helps to keep the domed shape. I use a potter's wheel with radius dishes mounted on it for this purpose but there are other, less expensive ways of doing it. There is lots of information on this topic on the Internet in guitar builder forums and sites if you do a Google search. You'll also find information on how to build dishes, soleras and forms as well.
BTW, radiiusing isn't absolutely necessary but I find it makes for a better instrument. Because of the physics of the domed shape, it allows you to build stronger and thinner as well. Some builders, especially beginners, will choose to keep their sound boards flat and simply bend the backs over the curved sides. As with anything, there are many ways and many degrees of doing things.
Good luck.

Rubbertoe
11-25-2009, 01:07 PM
Thanks for the advice, Chuck. I'll check out those guitar building forums.

Mahalo!

Dominator
11-25-2009, 01:36 PM
I did a tutorial article for Uke Talk a while back explaining the process I use for making my domed dishes. I learned from Mike Chock at Hanalima and basically used his information modified to suit my needs.

http://uketalk.com/luthier-tutorials/domed-dish.htm

Sven
11-25-2009, 07:54 PM
Yes! That article was a real find for me when I did my dish two years ago. The warning at the end about the dust is not a joke - try doing it outdoors.

I still build with flat tops though, haven't got around to put a radius in my solera (a fact that I guess makes it not a solera).

Sven

Rubbertoe
11-25-2009, 09:04 PM
Awesome tutorial Dom! I'll have to do a little more research but as I'm an uber-noob when it comes to woodworking, let alone luthery I'll have to plan it for a couple ukes down the line. Maybe one day I'll be building smooth sounding ukes like Luthier Vandross... yeah, I said it! Hello? Is this thing on?

Pete Howlett
11-26-2009, 12:24 AM
We had an old boy at college who headed up the CDTdepartment. He had formerly worked for Rolls Royce and was an incredible machinist. One prject in the plastics department was making metalaphones. This old boy used to do the metalwork side and always insisted that 'stressing' the bars a little produced a better tone. That is the principle behind doming the front - as Chuck said you can build thinner but also, you have a stronger structure, and in my opinion, a btter tone. I'm just doing a video of a true hand build - it's a concert Vita Uke for which I do not have my standard high tech form. I'll be doing the first part tonight and you can see how I've domed the top...

Dibblet
11-26-2009, 04:51 AM
I'm looking forward to seeing that Pete ;)

I was just talking about this with Rob and Chy in Hebden Bridge the other night. There were three Howlett sopranos in the same pub. You'd have loved it.

A few years ago there was a small piano factory close to me that I was given a tour of. They had an interesting way of putting the crown on a soundboard. There was a tall narrow box with a heater at the bottom that the new soundboard went into for several days until the wood was totally dry. While it was completely dry they glued the ribs on in a flat go bar deck. The crown appeared when the wood reabsorbed moisture from the atmosphere. The side where the ribs were glued was unable to expand but the other side could. He claimed that this produced a better sound due to different tensions in the wood. Anyone fancy doing a uke like that?

Pete Howlett
11-26-2009, 05:27 AM
I believe that Martin on their guitars originally glued the radiused braces on a flat board and if they sprang back, then hey, curved front...

Pete Howlett
11-26-2009, 05:31 AM
Dom - I would have made the arc by attaching a router to an 'arm' the length of the radius and cutting a 1/4" template. That's how I did it and then followed your protocol. However I would make one suggestion - glue 2 pieces of 3/4" ply together. I found that over time, my 3/4" board bowed....

Moore Bettah Ukuleles
11-26-2009, 07:36 AM
That is the principle behind doming the front - as Chuck said you can build thinner but also, you have a stronger structure, and in my opinion, a btter tone.

Yes, I neglected to mention that putting the top under tension will yield a better tone. Tension is also the reason a lacquered instrument sounds better in time as the lacquer continues to dry and shrink. Good point.

Flyfish57
11-26-2009, 07:06 PM
Do you guys radius the bridge plate as well? I would think you'd have to, but don't really know...I'd like to give this a try on my next tenor as well.

Dominator
11-26-2009, 08:16 PM
However I would make one suggestion - glue 2 pieces of 3/4" ply together. I found that over time, my 3/4" board bowed....

Thanks for the input Pete. I have made one from layers of ply and haven't yet noticed any warping of those made with the MDF.

Dominator
11-26-2009, 08:20 PM
Do you guys radius the bridge plate as well? I would think you'd have to, but don't really know...I'd like to give this a try on my next tenor as well.

If you are talking about the "bridge plate" then you don't do anything to it because it is thin enough to just bend into the shape when you glue it on via the go bar deck.

If you meant the actual bridge the answer is yes. After making the dish and applying the sand paper I take a smaller (6 or 8 inch) diameter piece of mdf and sand it on the dome to create the matching form for the bridge. Put sand paper on it and sand the bottoms of your bridges prior to gluing them on so they match the radius of the top.

Pete Howlett
11-26-2009, 11:28 PM
Shop built tools - hmmmmmm :drool:

I do the same as Dom only its a 2" x 8" wide piece - easier to hold in your bench vice. You can also stick sandpaper to the skids and use them to shape the bottoms of your braces or make the mono go-bar deck you see in my video.

Moore Bettah Ukuleles
11-27-2009, 05:09 AM
When I used to make wood bridge patches I would sand the patch to conform to the radiius. I doubt if it's really necessary. But certainly the bridge needs that curve in it.

RonS
11-27-2009, 05:45 AM
When I used to make wood bridge patches...


What do you do now?

Timbuck
11-28-2009, 03:01 AM
If you are talking about the "bridge plate" then you don't do anything to it because it is thin enough to just bend into the shape when you glue it on via the go bar deck.

If you meant the actual bridge the answer is yes. After making the dish and applying the sand paper I take a smaller (6 or 8 inch) diameter piece of mdf and sand it on the dome to create the matching form for the bridge. Put sand paper on it and sand the bottoms of your bridges prior to gluing them on so they match the radius of the top.
Using the "Pythagoras Theorem" I calculate that for a bridge at 2.5" wide fitted to a 22 foot radius, you only have to remove .0029" of material from under the bridge centre to make a perfect fit...Thats about the thickness of a Human hair.:D.

Dominator
11-28-2009, 10:45 AM
Using the "Pythagoras Theorem" I calculate that for a bridge at 2.5" wide fitted to a 22 foot radius, you only have to remove .0029" of material from under the bridge centre to make a perfect fit...Thats about the thickness of a Human hair.:D.

That may be true (I'm not smart enough for those kinds of calculations :)) but using a 20 foot radius my bridge will rock slightly left and right until I sand the bottom and get it fitted properly.

Timbuck
11-28-2009, 11:02 AM
Yes thats true! Dom.. it's amazing how big a few thou: can be, when you are working to fine limits...as I'm finding out on my Dovetail neck joints.

ecosteel
11-30-2009, 05:26 PM
I take a smaller (6 or 8 inch) diameter piece of mdf and sand it on the dome to create the matching form for the bridge. Put sand paper on it and sand the bottoms of your bridges prior to gluing them on so they match the radius of the top. Hey Dominator, I knew there must be a clever way of doing this. Sweet. cheers Steve

Dominator
12-01-2009, 07:57 AM
No problem. Glad to help Steve.

Matt Clara
12-01-2009, 12:18 PM
If the lower part of the soundboard, south of the sound port, or hole, is domed, and the board north of the sound hole is flat, the domed area is necessarily higher. Does one need to account for that change in height with slimmer bridges?

ecosteel
12-01-2009, 03:38 PM
Hi Mattclara
If the lower part of the soundboard, south of the sound port, or hole, is domed, and the board north of the sound hole is flat, the domed area is necessarily higher. Does one need to account for that change in height with slimmer bridges? I'm putting a 20' radius dome on my uke tops and the amount of doming is not a lot I'd guess it's 1mm higher in the middle than the sides on a soprano so with that radius it's not a huge issue. cheers Steve

donnercruz
12-03-2009, 10:44 AM
I sent this to Pete's email, but thought it would be great to get an answer here, so:

Hey Pete,

I was watching your video on making/using a solera. I have a couple questions.

Is the middle brace below the sound hole made flat or with a radius?

Do you keep the neck at a 90 degree angle, since the upper part of the uke is flat or do you angle it a little because of the radius in the lower body?

Thanks

thistle3585
12-15-2009, 03:34 AM
Thought I'd dig this thread up and post this link to how to build one using a wedge system. Graham McDonald also outlines the process in his books.

http://www.anzlf.com/viewtopic.php?t=231

Timbuck
12-15-2009, 06:38 AM
Hi Mattclara I'm putting a 20' radius dome on my uke tops and the amount of doming is not a lot I'd guess it's 1mm higher in the middle than the sides on a soprano so with that radius it's not a huge issue. cheers Steve
Closer to 1/2 mm I make it..Hardly worth the trouble.;) Go for 10' rad if you want approx: 1mm proud

ChuckBarnett
04-19-2017, 10:31 AM
First instrument builder here...
As I understand it from the wisdom here, there are 3 options to soundboards:
1. Flat
2. Radiused in a round dish
3. Somehow flat on the lower (?) bout and then angled thinner on the upper end??
I was planning to radius the back of this tenor at 15' and the top at 20'.
Perhaps this is simpler than I am making it?
I do appreciate this forum!!
Chuck (not THE Chuck) Barnett ;-)

Michael N.
04-19-2017, 11:03 AM
I've done dozens of instruments with flat soundboards. Sound perfectly fine to me. In fact to prove that radiused is better than flat you would have to build two virtually identical instruments and (preferably) stick them in a blind test.

sequoia
04-19-2017, 06:13 PM
I've done dozens of instruments with flat soundboards. Sound perfectly fine to me. In fact to prove that radiused is better than flat you would have to build two virtually identical instruments and (preferably) stick them in a blind test.

I am also of the flat-top school and they sound fine to me... Also a lot easier. Radiusing the top brings some advantages but also brings in a couple of troublesome issues. the first of which is your bridge will need to lay flat on there somehow (do able) and then there are binding routing issues to get a good binding channel on a radiused top (also do able or just don't bother to bind). There are other issues too which might rear their ugly little heads that I won't go into. I would say since this is your first build, just leave the top flat and the uke will sound just fine if you have thinned and braced your top correctly. You have other issues to deal with without trying to radius' the top on a first build. The back however is easier to radius with fewer issues so definitely radius that. 15' is pretty subtle. You can go more radical than that. Don't forget to taper the sides! Good luck and don't forget to send pitchers!

ChuckBarnett
04-19-2017, 08:25 PM
Thanks for the encouragement. -)
The thinning of the top certainly baffles me. Tone tap tuning is a deep mystery and i feel I've no clue what I'm doing. I've got the redwood top to a shade over 10 thousandths and have no idea if that is too thick or too thin. I guess it being as you mentioned my first build i should simply get it done and give up on doing a great job. But that frustrates the daylights out of me.

Timbuck
04-20-2017, 03:54 AM
I think you mean 100 thou .. 10 thou is shaving thick ..aim for .075" ish.

ChuckBarnett
04-20-2017, 06:53 AM
Yes, my math brain is deficit. :-) So why do I hear from some don't go that thin, yet you and some others think it's okay to go that thin with redwood? One person I have talked to said you can go too thin, past the point where you can tap nice tone to a point where the board sounds like cardboard. I'm also concerned about going to thin in view of some instruments that I have seen that are so thin that the braces would actually be discerned on the surface of the top. Remember, this is my first shot at this. I have no experience and thus I ask many, many questions. I apologize for inundating this forum with my questions in ignorance. Once I get through this first one I will be a whole lot happier. :-)

sequoia
04-20-2017, 07:20 PM
I apologize for inundating this forum with my questions in ignorance. Once I get through this first one I will be a whole lot happier. :-)

No problem Chuck. It IS tough. But here is the thing: Until you make a few and tap a few you don't have any reference in your mind to refer too. It is not a hard thing, it just takes some learning. I do not claim to have mastered this part of the process, but I have progressed to the point where I'm starting to hear what might be a good thickness. In the absence of experience, just aim for a thickness and write it down so next time you have a reference. I've built three redwood topped ukes and talked with people who build with redwood a lot. In my limited experience it seems to me that redwood really behaves like the softwood that it is and likes to be a little thicker than you think. I think I over thinned my first two tops and while the ukes sound ok they have no cajones if you know what I mean. Redwood is a funny wood. The sound is quite delicate and pretty if you are of that mind... In my experience and others I've talked with is the stuff likes to be a little thicker on the side of thinness which is like 80-85+ mil. Kinda thick or else it seems to rat out if you dig in. Personally not my first choice in tone wood even though I live in redwood country and it is all around me. Also it not that redwood sounds bad, it is just a question of taste and what kind of sound you are looking for. The nice thing about building your own uke is that you can get that exact sound that sounds good to you and that is where the fun starts. Oh, and it never ends.

ChuckBarnett
04-20-2017, 07:41 PM
Thank you, Sequoia! I appreciate your taking the time to give me a little perspective. I've decided to go with about .085 and call it good at that. I have been doing a pretty fair job of making notes on this project. Upcoming, I have some decisions to make in other areas such as what sort of bridge to use, how to attach the neck, what to do about binding. A lot of research I expect. :-)

finkdaddy
09-06-2017, 12:59 PM
If you are talking about the "bridge plate" then you don't do anything to it because it is thin enough to just bend into the shape when you glue it on via the go bar deck.

If you meant the actual bridge the answer is yes. After making the dish and applying the sand paper I take a smaller (6 or 8 inch) diameter piece of mdf and sand it on the dome to create the matching form for the bridge. Put sand paper on it and sand the bottoms of your bridges prior to gluing them on so they match the radius of the top.

This is a great idea! I've been searching the forums all day trying to find info like this. Thanks!

finkdaddy
09-06-2017, 01:12 PM
Don't forget to taper the sides!

Sequoia, I am going to be radiusing the backs of my next line of builds. Everyone says to taper the sides as well as using a radius dish. I'm having trouble wrapping my head around that geometry. If you taper the sides, wouldn't shaping them with the radius dish wipe out any taper that you added earlier?

sequoia
09-06-2017, 07:11 PM
Sequoia, I am going to be radiusing the backs of my next line of builds. Everyone says to taper the sides as well as using a radius dish. I'm having trouble wrapping my head around that geometry. If you taper the sides, wouldn't shaping them with the radius dish wipe out any taper that you added earlier?

I don't use a radius dish to taper my sides. I just make my neck block lower than my tail block by a quarter inch, glue in my linings in a continuous line head to tail (not critical), plane sides down to linings and then sand everything flat on a flat surface. Viola! One quarter inch tapered sides. No stinking radius dishes required.

Alytw
09-07-2017, 03:36 AM
Sequoia, I am going to be radiusing the backs of my next line of builds. Everyone says to taper the sides as well as using a radius dish. I'm having trouble wrapping my head around that geometry. If you taper the sides, wouldn't shaping them with the radius dish wipe out any taper that you added earlier?

No. The dish is concave..meaning that the deepest part is the centre. If you were to put a flat plane on the dish, only parts of the plane would touch the curve (the corners of the ends of the plane because they are the furthest away from the centre of the dish. This assumes that the length of the plane is greater than the width).

Similarly, with your sides in the mold, you gradually sand on the dish, more material is removed from each end before the midline (waist) would touch the sandpaper. If you were to take the sides apart and stretch them out, the waist area would be thicker than the ends (i.e. More would have been sanded from the ends than the waist). Having a taper saves you from excess sanding.

finkdaddy
09-07-2017, 04:40 AM
No. The dish is concave..meaning that the deepest part is the centre. If you were to put a flat plane on the dish, only parts of the plane would touch the curve (the corners of the ends of the plane because they are the furthest away from the centre of the dish. This assumes that the length of the plane is greater than the width).

Similarly, with your sides in the mold, you gradually sand on the dish, more material is removed from each end before the midline (waist) would touch the sandpaper. If you were to take the sides apart and stretch them out, the waist area would be thicker than the ends (i.e. More would have been sanded from the ends than the waist). Having a taper saves you from excess sanding.

Perfect explanation. Thanks guys!

Kevin Waldron
09-07-2017, 07:37 AM
Enclosing examples........ one 3D and the other a 2D template drawings........ if you've purchased a template set from us it will have the tapered sides and straight side as well.....we often get asked about my is it not flat...... 102881102882

kw