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Assembly with domed soundboard (Read 26946 times)
Matt Blacka
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MAKAIO Ukuleles Australia

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Re: Assembly with domed soundboard
Reply #15 - Sep 9th, 2008 at 8:39pm
 
Hi Mark,

I probably should have made myself a little clearer. By pre-bent sides, I was refering to the flat pieces of side wood, before they are bent. Its easiest to cut the shape of the sides while they are in this state.

It is difficult to explain, but for my designs, I have started with a rectangular shape for the sides, that is 2.75" high at each end (tail and heel areas). I have then applied a a certain profile above above and below this rectangle, that allows the top and bottom of the sides, when bent, to fit the domes for all locations around the uke perimeter. If you would like, I could try to send you some sketches/CAD drawings to help explain this a little better.

I have done some calculations and CAD drawings which indicate that the bridge should be a little higher when using the domed soundboard, so as to not end up with too higher saddle. Asa has a magic number for the difference between the height of the bridge and the thickness of a fretboard for flat top ukes (I would have to look up what it is, but I have it printed somewhere), but I think this number needs to increase for the domed tops. I will be investigating this more when I come to cutting the bridges.

I have seen a jig that someone made (can't remember where now), that was basically a solera for holding the bent sides, with a dished board as the base facing up, and a dished board for the top facing down. The dished boards were pinned in the centre with some way of keeping them alligned correctly, and could be rotated. The idea was to stick sandpaper on the insides of the dishes, and then use them to sand down the top and bottom edges of the bent sides to have the domed profile. It was interesting, and looked like it would work.

Anyway,

I will try to got some more info and pictures up here for the methods I used and the outcomes, when I get the chance.

Matt
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MAKAIO Ukuleles, Australia www.makaioukuleles.blogspot.com
 
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Acabooe
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Re: Assembly with domed soundboard
Reply #16 - Sep 10th, 2008 at 8:42am
 
Hey Matt,
I would be interested in seeing some sketches about it.
I don't have CAD so I am not sure if that would affect my ability to see them, but if not then could you explain it a bit more?
I have see Mike Chock do something similar to the process you described with putting sand paper in a dished workboard and sanding to make stuf fit, it is pretty neat.
Aloha
Bob
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Wood_Butcher
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Without music, the world
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Lake Stevens, WA
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Re: Assembly with domed soundboard
Reply #17 - Sep 10th, 2008 at 1:09pm
 
Matt,

Thanks for the follow up.  I actually understood your explanations.  Your info has been very helpful.  I also have no CAD software at this time, but do appreciate your offer.


Thanks immensely,
Mark
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Thanks, Mike and Asa!
 
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Ukeman
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Re: Assembly with domed soundboard
Reply #18 - Sep 22nd, 2008 at 11:08am
 
aloha all,

Thought I'd reply to your domed assembly queries. I use domed workboards and domed assembly boards for this process, 15  for soundboards to 25 degrees for  backs. Sounds like alot but actually if you place a short straightedge across your domed workboard you will see that in a 6 inch length the lowest point of the dome is about a meager 16th inch while in a 12 inch length it may increase to about an eight inch...not much, just enough to keep plates in tension.

Make plenty domed workboards...use one if making spanish style into a holding , assembly jig.

Make one simply a sanding jig place 100 grit stickit sandpaper onto workboard in adjacent rows..or buy a giant disc floor sander 100 grit and contact glue to workboard.

Use sanding dome board for all parts going on to sound and back plates ie: grafts, patches, tonebars and enharmonic bars.Simple way to sand is mark the surfaces to be sanded in dome with felt pen....sand in dome till no more felt pen marks...install under go-bar deck with a domed workboard underneath plate and whatever piece you are gluing on. Always sand in dome and assemble in dome.

If you want to adjust backset or foward set of your neck angle to plate...this can be done at the neck table on your neck, prior to installing soundboard in the flyswatter phase....add a shim to the end of the neck table to create positive neck set, sand off a bit at the neck table to create a negative angle.

In a flat regular holding jig you can insert your bent ribs and fit...mark the showing edges with felt pen and sand with a domed sander until no felt marks. These domed rib edges will be glued to your soundboard ala spanish style in your domed assembly jig to your neck soundboard asembly. Now for the back plate.

Mark rib edges and tentalones ...clamp a domed workboard with sandpaper to work table, pick up assembly jig turn over and sand by rotating on domed sandpaper board till marks gone, fit and assemble back to ribs.all done. ukeman
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Wood_Butcher
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Re: Assembly with domed soundboard
Reply #19 - Sep 24th, 2008 at 2:10am
 
Hi,

I'd like to pursue this idea a litle further.

Now that I have shaped and glued all of the bars and bridge plate on the soundboard, I have noticed an interesting shape developing.

The lower bout has developed a spherical shape having retained the shape of the dished workboard

The upper bout is cylindrical.  It is holding the curve formed by the two braces which run from bass to treble.  It is flat from the waist bar to the neck.  I will add that I didn't glue in the sound hole patces yet.

I am sure that the entire top would form a spherical shape if I sanded the sides in the dish and glued the top to them as Ukeman suggested in the previous post.

What I would like to consider is to leave the top in the shape it presently holds by only sanding the lower bout in the dish shape.  It would seem to make the neck to body joint a straight fit as if you were building a flat top instrument.

This seems to be a lot like what Likeke was suggesting on page one of this thread.

If this is what any of you are doing, I'd like to discuss it furthe.  Particularily to get some ideas on fitting the sides, such as modifying a dish board or whatever you might have tried.

Sorry about the long story, I just couldn"t come up with a shorter way to say it.

Thanks,

Mark
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Thanks, Mike and Asa!
 
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Wood_Butcher
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Re: Assembly with domed soundboard
Reply #20 - Jan 5th, 2009 at 4:00pm
 
Hoping to get somebody who is building radiused instruments to engage in an exchange of ideas about building.  Here's a photo of a motorized sander I built.

...

Another shot with the radiused work board removed.

...

A close up of the drive mechanism for the work board.

...

An interior shot of the pulleys to get from 1725 RPM to about 150 RPM.

...

And a shot showing how I am sanding the sides to match the radius.

...

Since I am using a Spanish heel, I have glued in the heel block.  Then I sanded the top edges of the sides to match the top.  I will glue in the tentalones and re-sand them to match the contour.  Later, the neck ends of the sides will be trimmed to receive the neck.  I will glue the neck and top together first, and then glue the sides to the top as per the Hanalima book.  I then plan on shaping the back edges of the sides and back tentalones in a similar manner as the top, after which I will glue on the back.
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Thanks, Mike and Asa!
 
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Wood_Butcher
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Re: Assembly with domed soundboard
Reply #21 - Jan 5th, 2009 at 4:04pm
 
Ooops.  Hit the enter button by mistake.

Having said all of that like I know what I am talking about, I will have to admit this is all theory and have never done this before.  This is where I would like some feed back from anybody who has had more experience with this  to see if my ideas are making sense.

Thanks,

Mark
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Thanks, Mike and Asa!
 
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Ukeman
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Re: Assembly with domed soundboard
Reply #22 - Jan 13th, 2009 at 3:49pm
 
Hey Fellow Domers! Though i'd squeak a bit and add my doming methods to this thread. I make my domed workboards with 15 foot radius for the backs and 25 foot for the soundboards. For guitars these are cool radii, for a tenor ukulele the dome at 25 and 15' radii is very slight, but enough to get the tops and backs in tension. My workboards are used for installation ala spanish style, another is used for under go-bar or any clamping situation to stay in the dome and the last is used for sanding all bars and braces, patches and grafts prior to installation. This means when sanded correctly the bars are never perpendicular to the soundboard but at a slight lean if one sands in the dome. My soundboard to neck table attachment is where i adjust 2 degrees or so to accomodate the dome of the soundboard...if you sand the neck table its such a small area its easy to do and a slight neck back set is desireable.

All my ribs if to be fitted to domed surfaces are not tapered! I bend the shapes, fit and clamp the ribs in a 2 ply thick form adapted to fit over a domed workboard and ribs are then domed and installed to soundboard, which is in a domed assembly jig. The backs after tentalones are installed are fitted and sanded with a domed sanding board and same domed workboard is used to clamp the fitted back plate. If you have a handy shimpo electric wheel or any potters wheel you can take off the  batten plates and install a domed workplate onto the wheel...build a holding device to keep your uke body level and lower assembled uke and ribs to the rotating domed dish on the potters wheel and with 100 grit sandpaper you can dome in 20 seconds....anyway doming is fun   laters   ukeman
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Don_Orgeman
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Re: Assembly with domed soundboard
Reply #23 - Jan 14th, 2009 at 5:21am
 
Hey All:

Here's a link for a great tutorial on how to make a sanding dish using a router.

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

Don
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Ukeman
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Re: Assembly with domed soundboard
Reply #24 - Feb 3rd, 2009 at 4:32pm
 
aloha all message board posters and 'ukulele builders...here is another reason to join the 'Ukulele Guild of Hawaii: Send your paltry 45.00 to the 'Ukulele Guild of Hawaii at PO BOX 894426 Mililani, Hawaii 96789 for you one year membership.

January's issue 2009 included a fabulous Play it foward Tip via veteran Builder Bob Gleason ala Pegasus Guitars and 'Ukuleles who is sending this lateral tip from Pohaku 'Ukulele's Pete Hurney...and the tip is:

Making a domed sanding board by using your drill press!
Awesome...just need an extended workboard on you drill press to accomodate a sanding domed dish..Bob uses a formica workboard to make the top a bit slippery and by indexing the workboard with a centered pin...that mates with the underside center of the sanding dish, think record player the dish will freely spin....mount a rubber sanding drum Bob uses a 2" diameter drum into your drill press..aligned so that it just mates with the outside diameter of your sanding dish and the roating drill press drum will drive the domed sanding dish...Bob simply waxes the formica surface of dish and workboard...Pete Hurney used his domed dish mounted on a lazy susan bearing...this indeed is my next project.....way cheaper than modifying an electric Shimpo Potters wheel....and the tip of the Year...which is the first tip of 2009 from the 'Ukulele Guild of Hawaii!

Re join us at UGH for 2009   good things will happen    laters  ukeman
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