Another "my First Acoustic Build"

[pariah223]

Well, i have been working on this acoustic for quite a while actually and just took my first pictures today. There seems to be a lack of progress threads that i know i personally enjoy so im sure im not the only one. I have the top done, the sides bend (just about, one is still cooling in the jig) the back is ready to have its braces glued in my go bar press. So here are the shots so far. Still have alot of sanding and stuff to do, but here ya go!

I would post all my jigs and stuff i made but theres just so many of them and you have all seen most of them before. The only slightly unique item i have is my bender just because of the way i made and operate it. Its all explained in this thread in case anyone is curious.

http://projectguitar.ibforums.com/index.php?showtopic=35826

[Daniel Sorbera]

Bracing looks a bit on the heavy side, but whatever.

FWIW I usually don't brace the top/back until the sides are ready to glue them to. That way the top/back doesn't sit around with bracing on it but nothing holding it in place keeping it from warping.

[pariah223]

hm thats an interesting point. i have basically been following the kinkaid book direction, but i am quickly learning that the book is not the best. As far as the bracing being heavy, i could remove more material if it may prove to be an issue. Again, i went to the kinkaid specs on the width and the height and stuff, but he didnt go into much detail about how much to take off.. he said "go by tap tone" which is great, if you know what to listen for, but this being my first acoustic... i have no real references. I also noticed that the picture does make the bracing look alot bulkier than it does in real life... particularly those smaller braces, they look like logs in the picture

Edited May 12, 2008 by pariah223

[carousel182]

hey man! nice work on this, I can't wait to get restarted on mine. Right when I setup this electric and buff it I'm restarting.

[fryovanni]

Bracing can be a tricky thing to wrap your head around, but it will make more sense as you go.

A couple things that may be helpful. Common dimensions for my main X bracing; 1/2"(medium/mild stiffness) to 5/8"(stiff) tall at the crossing. I use 1/4" wide, I used to also use 5/16" (again main X). I do not scallop above the main X crossing, this is where you need strength, I do taper to the sides, but it is just a straight taper. Upper Transverse I would leave full height(just taper the sides). I usually inlet my bracing above the waist, sometimes the lower main X legs, sometimes I feather them. You want to be sure to feather or inlet one way or the other where parts meet to minimise stress risers. Height increases strength much more than width, so tapering the sides of your braces has little effect on strength, reducing height reduces strength very fast.

Look at your lower tone bars. Notice that the scallops form up a kind of oval. This area behind the bridge shapes a lot of the responce (especially mids). When you are working on the scallops, tapering or whatever keep that in mind. Some use different bracing configurations that adjust the stiffness of this area, but the concept is to work with your long grain and cross grain(much lower typically than the long) to control the stiffness in this area. Adjusting the scallops in that area change the responce a little slower when tapping. You will notice a rapid change in the responce of the top when you adjust your scallops (or taper if your doing non scalloped bracing) in the main X near the bridge. Keep that in mind when you go about carving here and there and tap.

I try to get my main X adjusted pretty close early. Then I am able to make minor changes to the feather braces, tone bars, and lower X legs. Paying close attension to a balanced tap responce. I am very mindful of how I want my mids when I am carving behind the bridge. I also try to keep in mind how close I am to structural elements of the rim and what not as I work the outer bracing. You also have to remember that the top will stiffen back up a notch or two as soon as it attaches to the rim. So a quick check and possibly small adjustment or two is good after you attach the top to the rim. It is also handy to be able to finsh your top and back the same day so you can compair them before attaching.

I hope some of that kinda makes sense. As far as what I listen for when tapping and flexing. I want to feel the top loosen up and go from a tight ping to a nice ringing responce. As soon as it starts to loosen up focus on balancing the responce around the board with very small changes.

Your project is looking really nice! Keep up the good work

[pariah223]

thanks for that great reply.. im actually printing that whole reply out and throwing it in my binder.. another question, i found people talking of this once before, but cant seem to find it again.. is there some kind of stain or rust remover that removes the burn marks in wood caused by bending?

[fryovanni]

thanks for that great reply.. im actually printing that whole reply out and throwing it in my binder.. another question, i found people talking of this once before, but cant seem to find it again.. is there some kind of stain or rust remover that removes the burn marks in wood caused by bending?

I have never heard of something that removes scortched wood, other than sanding or scraping. I seem to recall mention of using wood bleach to remove staining after bending(but that was water introduced staining).

To add just a bit of what I try to use as a guide for myself while I go through the bracing and such. I will try to describe what I listen for and feel.

1. When I thickness my soundboard. I try to start by thicknessing to .140" (this is just a thickness I have always used to get a feel for individual soundboards). I use a similar thickness because it helps me compair apples to apples. I flex the top to get a feel for its stiffness. I am trying to get a sense of its longtitudinal stiffness, and a sense of how stiff its cross grain is compaired to its longtitudinal. I also tap the board and listen to how it rings. I then sand it taking about .003-.005" per. pass. I want to feel how fast it is losing stiffness, and how its ring changes. At a point there is a real drop in the tone of the tap and the top feels much more flexble(just starts to feel a tiny bit floppy). You have to consider cross grain stiffness, because tops with high cross grain will not loosen up as much, and you can take them too far if you are not careful. I think of the soundboard kinda like a drum head (this is helpful if your a drummer). A thick head is dryer, more condensed sounding, a thin skin is louder, more dynamic, but gets muddy if you work it too hard. You don't want to go too far one way or the other, you want to find the spot that suits you in that range. I want to brace to suit the soundboard, so you need to have a good feel for your soundboard.

2. After I attach my bracing. I start by tapering off all the brace ends closer to dimension(little effect, but gets rid of a bunch of mass). I shape the sides of all the braces (again removes mass, but without removing height you lose little stiffness). Next I bring my main X down to my target height(between 1/2" and 5/8", depending on what I am building to). Next I taper off my upper X legs(it is a gentle taper, and not scalloped). The tranverse has been shaped on its sides, I will develop a mild transition to the ends that have been tapered for inletting (that is it for the tranverse). I work a mild straight taper into my lower X legs(this is not to final height just sets a clean angle for my tuning). I also develop similar mild angles on my tone bars and finger braces(not final height, but sets a nice angled line to the end tapers). you can touch up the sides of all the braces again at that point. That gives me the bulk of the main structural layout. At that point the top still sounds tight when tapped.

3. Next step is to approach the first hint of the top loosening up. I do this first focusing on the lower X legs, closer to the bridge. If I am scalloping I mark my peaks and centers, and remove wood slowely, until I hear the first hint that the top is loosening up. The top will sound like a tight ping when tapped and the bracing is too tight. You will hear the ring start to open up(not a tight ping, the will just start to vibrate longer, pitch hints at dropping) when you are getting close. Now you want to be darn carful how much you remove from the main X legs near the bridge, so lay off that area. Since it has started to loosen you will be able to start hearing changes when shaping your tone bars and finger braces. Before all you would have heard was ping most likely even if you carved all the tone bars and fingers completely away.

4. Now I mark my scallop peaks and centers, or breaking points if I an using tapers. I like to work my way around the tone bars and fingers to get an even ring when tapped at this point(this is just keeping things balanced out and lets me keep a good point of reference). What you want to hear is a nice ring when tapped all over, you want to try to eliminate dead areas(that just thud, you will find you can work these out with small changes). The soundboard should have a pretty tight, but even musical ring at that point.

5. From there on out you will make very small changes. You will want to loosen the top up a bit more to make the ring that you started to develop become more notable(looser), but how much depends on what you are going for. The tone bars and finger braces can be adjusted to suit your preference for highs, mids, and lows. Just keep control over the balanced responce as you tap around, try to avoid making radical changes in one area, without balancing the responce. You won't find many specifics about this in books, because this is all subjective to what you want to achieve. I like to have a goal in mind when I select and thickness my soundboard, and carry the idea through this stage.

6. I try to make sure my back has a bit tighter tap than the top. It is handy to have the back and top in front of you, so you can adjust acordingly.

7. Bear in mind the top and back will tighten up after you attach them to the rim. Adjusting them just a little looser than what you want after they are attached works well, but you can get a feel for this change by attaching your first couple tops and listen to the change, then adjust the bracing a bit in place. You can make small changes to the thickness of the soundboard after the box is closed (some like to thin the outer edges a bit to loosen the top a bit more, tapping and pressing the soundboard can give you a good idea as to how much you are effecting things).

Again that is just the way I go about things. It is a good idea to find out how other people go about doing these things. Try it and see what works best for you. There are many methods people use, from deflection to tuning to pitch or using patterns.

Peace,Rich

[pariah223]

ok Rich, how much do i owe ya?

[GoodWood]

I use a sandbag ankle weight to hold down the back or top to the dish.

I am going onto building a standard dread (slight sloped shoulders) at this point, Red /adi? top, maple burl rosette, Hondo mahogany, Working on the molds still. Nothing to take pictures of yet,

I think I took too much off my first (second) top.

I would do a cheap wood top and brace it all up and tune that first to get a good feel for this. It really helps.

[fryovanni]

I use a sandbag ankle weight to hold down the back or top to the dish.

GW,

Do you do that to try to keep the woods shape if you wait a while before attaching it? I am always leary of blocking one side of a piece of woods exposure to air while exposing the other. As long as you have good humidity control I don't suppose it is going to be a problem.

On the subject of moisture content, and timing to attach to the rim...

Timing/humidity level/moisture level of the soundboard and bracing during your work up to the point you attach is an interesting subject though. There is a logic to driving the moisture content low while working and up through attaching it to the rim. Idea being the dome will hold its shape better and never be driven flat(or concave) by severe drying, and may add a degree of pre-tension to the soundboard that may make it sound better. Not totally sure how I feel about the level of pre-tension that is desirable, or if overdrying and possibly reducing the radius(maybe 42' instead of 25') would be a reasonable step, or if allowing for average conditions and using say a 25' radius works to the same end in terms of resistance to flattening(less the pre-tension of course). I have watched seasonal changes in the dimensions and have a pretty good grip on that, but optimal tensioning still is a bit of a mystery to me.

I would love to hear what you guys think, or how you go about working with your tops during these phases of work.

Peace,Rich

[pariah223]

has anyone messed around with mahogany for your kerfing? I am kind of low on the spruce department but have a major surplus of mahogany from a cabinet maker who gives me the stuff he would burn. I have seen that mahogany can be used... would this have any impact on anything that you guys know of?

EDIT: Funny, i just looked at stewmac, and they only offer mahogany and basswood... so maybe this was a dumb question, but ill leave it up to see what you guys think.

Edited May 14, 2008 by pariah223

[Daniel Sorbera]

You mean for the kerfed lining? I've never heard of spruce being used. I have used both mahogany and basswood depending on what color I want for that guitar.

[Mattia]

Spruce is not uncommon, but it's not as common as mahogany, baswood or cedrella (spanish cedar) for lining material.

[GoodWood]

Fryovanni, yes I use it to keep the back in shape You could make a jig to support a weight on top of it I suppose, for better air flow. I just don't think its a good idea to have the back flopping around for a month while you ding around getting everything else done.

But now I will have the top kerf and back kerf READY to accept either side as soon as the sides are done. My first side set inlet was a disaster. From now on I will put side extensors off the X braces so the kerf stops exactly where I need it.

[Mattia]

I keep unbraced thin plates lying around in a relatively climate controlled area; once braced, I want them on that guitar within 2-3 days, and either weight them lightly or leave them in the go bar deck with one bar.

[fryovanni]

I keep unbraced thin plates lying around in a relatively climate controlled area; once braced, I want them on that guitar within 2-3 days, and either weight them lightly or leave them in the go bar deck with one bar.

I usually join tops and back, install rosettes and backstrips, get the thickness where I want it, and then just hang them in my shop until I am ready to brace them(which sometimes takes a while at the rate I build, LOL). I get the rim ready, edges radiused and what not and have then waiting in the mold. Then I attach the braces clean up the glue, and let them set up still clamped in the dish, sometimes I leave them overnight(sometimes it is an early morning then work with them in the early evening). I shape the top and back braces, notch the rim for inlet legs, and attach the first to the rim that evening or next day(if your noodling around your only going to be shaping for a couple hours), then the other attaches after the glue has set up on the first. So neither sets around braced for very long, before it is attached. I usually place a towel over my dish and place the back on that while it is waiting on it while the glue to set, no intentional weight or clamping although I think I left a 60-1/2 setting on the bracing one time. I thought about clamping both at the same time using my dishes as cauls, and may try that, but the process is pretty speedy as is, so that may never happen.

For linings, I use Spanish Cedar almost exclusively. I love the smell of that stuff There are many woods that are fine to use(mahogany,khaya, basswood, willow, spruce, soft maple and so on.... light, but strong, not prone to splitting, bends well and good stability is nice).

Rich

[pariah223]

oh wow, shows how much i know... for some reason i thought kerfing was spruce mostly... but im glad to hear its mahogany because i have more than i know what to do with... i also have some Spanish cedar... the smell of that stuff probably fills a guitar case if you leave it in there for a week. i might use that stuff just for the smell

[pariah223]

for kerfing, does it HAVE to be one long piece for each side or can it be in a few smaller sections. I could see the advantage to one continuous strip but i have a bunch of smaller than the right length pieces of different kinds of wood.. cedar being one of them and was wondering if i have the kerfing butted up and glued well, can it be in 2 or 3 pieces?

[fryovanni]

for kerfing, does it HAVE to be one long piece for each side or can it be in a few smaller sections. I could see the advantage to one continuous strip but i have a bunch of smaller than the right length pieces of different kinds of wood.. cedar being one of them and was wondering if i have the kerfing butted up and glued well, can it be in 2 or 3 pieces?

Some build with individual pieces(not continous kerfed strips), some use continous un-kerfed linings. Up to you.

I kinda like the ease of installing kerfed strips. I don't care if they are continous. There is a little difference in looks, but not a deal to me.

[pariah223]

i got a question about the sanding dish... i just put sandpaper on my dish and started sanding the top of the sides for the soundboard. I noticed right away that around the waist (i think its the waist.. the thinnest part) the dish dosnt touch, and it dosnt touch by like an 1/8 inch.. Is this normal, and i have to sand the rest until it all meets up? It may be an obvious answer, but i just dont wanna mess up after getting this far! Should i have done the kerfing after this step so i dont remove too much of it?

Edited May 28, 2008 by pariah223

[pariah223]

Kerfing is all done. here are a few shots showing the clamping and the final product

Sorry for the odd lighting... im far from a photographer

[carousel182]

Whenever I look at one of your pictures I say to myself "hey, I've seen that jig before!"

nice work!, I hope mine goes this smoothly

[pariah223]

Soundboard and back are all glued up, here is a shot of the back being clamped... and the last time all my hard work on the backside of the soundboard will be seen unless the guitar is ripped open

[fryovanni]

Soundboard and back are all glued up, here is a shot of the back being clamped... and the last time all my hard work on the backside of the soundboard will be seen unless the guitar is ripped open

Couple observations.

The braces that you did not inlet to the sides. You want to thin those to a thickness less than the thickness of the soundboard or feather them to nothing(more common approach). You create a stress riser that may lead to the braces popping loose by leaving them too rigid.

The upper part of your main X brace(above the crossing). You don't need to scallop those. The area above the crossing is all about structure and resisting the strings force that is trying to collapse the top. I usually use a mild taper, inletting the ends into the kerfed lining.

You can taper all the sides of your braces. This will remove a chunk of the mass, but remove little stiffness.

Out of curiosity how tall is the main X crossing?

My X crossing is usually between 1/2" and 5/8" depending on the size of the box.

Your finger braces can be tapered much more usually. These are less structural. I have never inlet a finger brace(they are just not substantial enough). I use these to fine tune the top, after the main structural elements are established.

Popsicle braces, I usually don't make mine quite that large(just FWIW).

Just some observations that I hope are helpful. The ends of your thicker non-inlet braces are concerning, the rest will just effect the way the top sounds.

Peace,Rich

Edited May 31, 2008 by fryovanni

[pariah223]

ill have to keep all those tips in mind for future builds. Unfortunately, i didn't get that post until after i closed the box.. but its all a learning process so if the whole thing collapses when i string it up, at least now ill know why. So bascially what your saying is if the brace isnt inlet into the kerfing, and it is too thick.. it will have no flexibility and if the soundboard changes shape due to string tension or humidity, the brace could pop loose? Is this a guarenteed thing? the only braces that arnt inlet into the kerfing are the really small ones and that one that the kerfing broke more than i planned on when i was trimming it (how do you trim your kerfing for the braces.. chisels?) Anyway, here is a shot of the closed box.. now im just a little concerned as to wether i should continue my journey or not with a (fatal?) design flaw. Oh, and the center of the x-brace is about 5/8 i believe. Whatever kinkaid's book says to bring it to.

Edited May 31, 2008 by pariah223