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Top thickness (Read 7102 times)
John_Mayes
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Top thickness
May 1st, 2004 at 7:35am
 
I'm curious guys.  How thick, on average, do you make your tops?  I know that the number will vary given the species, stiffness, grain orientation, but I'm curious about a ballpark figure.  Also how thick do you make your bridge plates?  And while we are at it we can all show pics of our bracing and such... I'll start... here is the 2nd uke I ever made.. ...

I think the top thickness on that one was around .070-.080..I'm trying to recall but I'm really gussing here.  I always determine thickness by how stiff the top feels cross grain.
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hapakid
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Re: Top thickness
Reply #1 - May 1st, 2004 at 2:06pm
 
Your ukes are really wonderful, John.  After five ukes, I'm not sure what to add to this conversation.
Top of the line ukes are often in the .060-.10" thick range, but those of us without thickness sanders are often at the mercy of our tools and their limitations.
I've only built tenors, but my tops have ranged from .090-.150" or so.  I'm sure I could have gone thinner on all of them, but I didn't have the tools or patience to do it.
I think tenors are somewhat forgiving because thicker tops give you a nice mellow midrange punch (nice for changalang and simple strumming for vocal accompaniment) at the expense of clarity on the high end, which guitar luthiers often desire.
Since I don't have a planer or a thickness sander, I have been thinning mine with a power hand planer, then laying the top on a belt sander to smooth out the sanding marks.
Jesse Tinsley
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paradiseukes
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Re: Top thickness
Reply #2 - Jun 18th, 2004 at 6:49am
 
I've built my ukes trying to keep the tops under .060.  The thickness sander I built seems to have about .004-.005 variance in the roller to table dimension so the thickness of my tops tends vary that much.  I measure in a half dozen places and stop sanding when the thickest part reaches .060 or under.  The finished uke does exhibit some top distortion near the bridge but I wouldn't call it unreasonable.  I've never measured the distortion and compared it against production ukes but that might not be a bad idea.  My uncalibrated eyeball says its less than on my father in laws Kamakas.  His Kamakas still sound better.

I try to make the bridge patch roughly the same thickness.   It's more difficult because the piece of wood that the bridge plate will be cut out off is smaller, it's harder to run through the sander.  I usually allow an inch of waste at both ends of the wood, the wood gets way thinner on the feed end, and I swap the wood end for end to balance it out as I sand.

Howard
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John_Mayes
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Re: Top thickness
Reply #3 - Jun 18th, 2004 at 8:08am
 
Thanks for the replies.  The latest uke I made (all Koa Tenor) had a top about .060-.065.  It was a great sounding uke.  One of the best sounding ukes I've ever played.  Of course I'm biased, but it really was nice.  I make my bridge plates pretty darn thin usually.  Somewhere in the neighborhood of .030-.040, but I laminate them with three pieces with crossing grain so it gives it great stiffness but very little negative impact on the tone.  The thicker the plate the more it dampens the vibrations of the top, and hurts tone.  Of course it is a catch 22 as if the plate is not big and thick enough then the top will distort.  Some distortion is not bad but of course excessive is not a good thing. The most important thing is to get the stiffness of the top correct.  No matter the thickness the stiffness should be correct in accordance with your style of building. 

I'd still like to see some more shots of bracing patterns.!
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Re: Top thickness
Reply #4 - Jun 18th, 2004 at 12:01pm
 
Wow I'm amazed at how you laminated three pieces to a finish thickness of .03 -.04"! I just glued in a bridge plate last night and measured a cut-off and it was like .04+ and I thought that was thin. Smiley

I notice that you don't have any soundhole/rosette reinforcement. Did you just not reach that step or do you not find any need for it at all?

Also is that your own design/shape?
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StringDoc
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Re: Top thickness
Reply #5 - Jun 18th, 2004 at 2:42pm
 
Not long ago I asked David Hurd the same question.
He has built over 600 ukuleles. Anyway, he refered me to some articles on his website. ukuleles.com.
Go to the site map and scroll down almost to the bottom where he has a section called Understanding and controlling instrament resonances. Then check out the various articles about measuring wood properties!

Nathan
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John_Mayes
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Re: Top thickness
Reply #6 - Jun 18th, 2004 at 6:05pm
 
Quote:
Wow I'm amazed at how you laminated three pieces to a finish thickness of .03 -.04"! I just glued in a bridge plate last night and measured a cut-off and it was like .04+ and I thought that was thin. Smiley

I notice that you don't have any soundhole/rosette reinforcement. Did you just not reach that step or do you not find any need for it at all?

Also is that your own design/shape?


Haha.. Well I put cutoffs though my drum sander and it can take them down as thin as I like.

I did put sound-hole reinforcement just not at that stage..Normally I do it before gluing it to the top but that was my 2nd uke I ever made so it was a work in progress.  I don't do the doubling of woof there but put two braces really close to the sound hole.  Seems to work well for me...sorta like a guitar's soundhole bracing. 

Andthe shape is from a Hanalima Tenor shape.. he bracing is a bit of my twist, but pretty faithful to the plan that the fine people here sell.  They make the best plans I've used hands down for ukes.... now if they would just do a traditional concert and soprano uke I'd buy them in a flash too! (hint hint)

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John_Mayes
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Re: Top thickness
Reply #7 - Jun 18th, 2004 at 6:12pm
 
Quote:
Not long ago I asked David Hurd the same question.
He has built over 600 ukuleles. Anyway, he refered me to some articles on his website. ukuleles.com.
Go to the site map and scroll down almost to the bottom where he has a section called Understanding and controlling instrament resonances. Then check out the various articles about measuring wood properties!

Nathan


David is a smart guy for sure.  His little article on string compensation is what got me thinking to do the moveable split saddle I came up with.  He approaches things a little different than me.  He seems to take a more scientific approach and I go with a more intuitive/feel (I'm sure he does some of that too), but it just goes to show there are many roads to rome.

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Re: Top thickness
Reply #8 - Jun 19th, 2004 at 2:23pm
 
John,

Personally, I have made two ukes.

My first was a tenor with sitka top, traditional soundhole and 3 fan braces with a spruce bridge plate.
I thicknessed my top to .080 then thinned out the edges around the back and side edges of the lower bout until it felt a little more flexible.
I think my measurements were around .065 at the edges. I split the bracing material out of sitka also. I chose the stiffest pieces then thinned them down alot smaller than the ones you had in your picture.
I finished the instrument in late December and havn't noticed any top deformation! The instrument has a well rounded sound that is pleasent, but I know that is subjective since I don't have much to compair it to.

My second instrument was a concert with an engleman top. I finished it about a month ago. It is a Kasha style instrument with a top and side port sound hole. I used a nice piece of engleman that had very tight grain. Compared to other pieces it seemed the stiffest.  I sanded it to .080 also and thinned out the edges. I used a thin (maybe .01 to .012) carbon fiber bridge plate. The braces were very small and light.
I am sorry to report that the top is sinking in front of the bridge and their are some ripples on the side corners of the bridge.  The sound is good and I am hoping that it doesn't get any worse. Chalk it up  to experience I guess!  In retrospect I might have made the top and braces a little thicker.  I would still thin the edges a little to loosen it up.

I would be curious to have Mike Chock comment on this subject since he has way more experience with Kasha braced ukes with Engleman spruce tops. (hint, hint)

Nathan
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John_Mayes
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Re: Top thickness
Reply #9 - Jun 19th, 2004 at 6:59pm
 
Cool deal.

Yeah the one pictured above was a good sounding uke but lacked in the bass department.  It had a killer sweet smooth sound and a great harmonic overtone structure, but needed a little extra bass.  I think that is mainly because the top was too thick.  the braces are wide (going off the hanalima plan), but are more low profile than the plan suggests.  only maybe a .250 tall (I'm guessing here from memory).

I've not used the Kasha system but I do like the concept.
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Re: Top thickness
Reply #10 - Jun 21st, 2004 at 10:01am
 
I am building my first uke from scratch.  Here is a pic of the bracing.  I can't tell you if it is good, bad, right or wrong.  I won't know what it sounds like until it is completed.  The top is .080 thick and the bridge patch is around .040. 

I looked at various pics I found in books or on the web and some showed the small diagonal pieces around the soundhole.  I decided to try it on this one which is a tenor.  I see that John does not use them.  Is it going to dampen the sound more by using them?  Is this just personal preference based on experience?
Dominator
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John_Mayes
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Re: Top thickness
Reply #11 - Jun 21st, 2004 at 10:42am
 
No I DO use them, just on that one it was an afterthought.  They did end up being on there before it was all said and done. 

Yours look pretty heavily braced, but hard to tell till you get em strung up.
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Re: Top thickness
Reply #12 - Jun 22nd, 2004 at 11:19am
 
Aloha all: Nathan, thought I 'd try to answer a few of your Kasha inquiries as best as I am able!

First off...the Hana Lima "ia Kasha /Schneider plans are exact downsized replicas of the last Kand S set of guitar plans with Kasha/Schneider bracings, prior to Schneiders passing!. With my own ukes I have eliminated some off the assymetrical bracings and reduced the number to 12 versus 16..on a tenor uke.
For the concerts the number is reduced further to 10 versus the original 16...which is shown on the concert K and S plans. I've modified the bracing patterns over the course of 10 years and key on structure...the braces are placed assymetrically and at tangents to the vertical grained soundboard to keep stuctural support..my bracings are thin mayhaps 3/16th at the bass long bar to 3/32nds at the stiffeners on each end of the bridge. The heights of each bar graduate rom the bass bar of about 1/4 inch and progressively lower toward the treble side to about 1/8th inch..my bridge patch is either a half patch then I will use the Transverse bar..the one horizontal to your saddle location or if a use a full bridge patch, I eliminate the transverse bar. The patch is laminated 3 piece and the bars are notched onto the plate.
If I am using side port holes and have no soundhole on the soundboard the assymetrical bracing is lengthened to drive more soundboard since I have no hole to worry about.

The curvy line from upper bout and a bit below the offset sidehole is a soundhole patch...3 veneers laminated and notched around the neck table .

The laminated waist bar is either omitted or placed at the end of your neck table glued to the neck table and then one end is fastened via a notch into a vertical stiffener on your rib between kerfed linings. The waist bar as shown on the plan will be cut to end at the width of the neck table, it doesnt connect rib to rib but neck table to rib and only on to the soundboard in the end of the neck table. Yes it's spanish construction for the neck and we do not use headblocks.
A working thickness for me is a rather hefty .090.
I join at this thickness...install any rosette or inlays and then thickness once more to about .080.
The braces are installed and I go about the process until boxed.
After I am boxed since I use side ports the boxed uke has no opennings.
I will then thin the soundboard and backboard of the uke along its perimeter tapering the plates from about 0ne and one half inches from the inside of the ukes perimeter all around both plates. The end thickness is around .060...Remember this is Tapered from this .060 thickness if I measured in just a 1/2 inch the toips would be thicker.
I will then hand cut in my side port hole starting with the oval pattern of a desired shape and size and start my first hole well within the pencilled final shape...I will then increase the size of my beginning oval by 1/8th increments and using a decibel reader a device to hand my uke by the volute of the neck and with a tool (the rubber gizmo that the Doc uses to test your reflexes) Steadily tap at the saddle location and record tap tone via a tuner and decibel reading via the Decibel reader..I do this in increments until I register a jump in decibels..If I enlarge the hole a bit more after this jump i notice that the returns will diminish so I suspect I have arrived at the right sized soundhole for the size and internal air volumne of my uke.
I have noticed: The decibel reading will increase until your hole is just the right size for whatever your uke air voulme is...loud
As the hole size increases the tap tone decreases.
When all is right with the universe...I now BIND. Hopefully I will post (read ASA will post) pictures of what I do...I am just computer inept at the moment....hope this helps  later  ukeman
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Re: Top thickness
Reply #13 - Jun 22nd, 2004 at 6:28pm
 
Mike,
Much thanks for your detailed explanation!
I'll have to admit I didn't order your plans but winged it from the micro plan on your website.  I think my braces are smaller than what you said!
I overlapped the braces over the bridgeplate, but they are not cut into it.  Also, I used carbon fiber cloth and made my own bridge plate with 2 ton epoxy.  It didn't seem real stable that way. In the future I would use factory made carbon fiber plates or wood! I also used a classical style bridge instead of the Kasha shape.
Nathan
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Re: Top thickness
Reply #14 - Aug 31st, 2004 at 9:35pm
 
When I'm about to brace a top up I just guess the thickness intuitively.  Tap um till the bugga sound right.  Den I brace up.  I think sanding down after you've boxed up is more important, cuz you're closer to finishing at that point than before you brace up.  Basically I don't worry about #s I'm more worried about sound.  Listen to your uke as you shape.  It'll tell you when it sounds right.  #s will only tell you how thick it is.  Shoots, aJ
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