Low end Aria renovation

Construction and repair of Classical Guitar and related instruments
amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Low end Aria renovation

Post by amezcua » Mon Feb 06, 2017 11:31 pm

There may be other Aria topics but I thought this was an interesting case on it`s own to chew over. I bought this Aria for the princely sum of £39 . First impression was the printed on or painted on rosette . Not that crucial to the sound though . There are no cracks or splits and the neck is straight. Spruce top and maybe some kind of rosewood back but a tobacco smell and dark varnish makes it hard to judge so far .
It arrived in tune . But gradually I noticed the belly sagging above the bridge and bulging below the bridge. Feeling the braces inside I found just 4 . None missing though . The sound was not right and reaching inside again I could feel the two centre braces are unglued for about 2 or 3 inches nearest the hole. With a lamp and mirror you also notice on the braces the whiskery surface of crudely cut wood . Square topped and the ends most likely just snapped off to length and stuck in place.
If this was made in Japan they will be falling on their swords as I describe one of the two central braces. One is fine grained and with vertical grain along it`s length . The bad one shows wider grain stripes crossing the line at 30 degrees to it`s length.The other two outer ones are a bit irrelevant when the centre half position is so neglected .
But this bellying confused me .The large strut below the hole keeps the belly dead flat across.The bridge was made to fit a mild concave but near the hole side the belly dips in the centre. The bridge shows no sign of lifting. A straight edge behind the bridge rocks left and right easily but as you check within an inch of the end block the same rocking happens.
I tested the belly for a few days with a wood screw fitted to a section of thick plywood internally . A mild turn on the screw brings the belly up to just over flat .Releasing after 2 days allows it to go back to where it was .
It`s a classical but I can see me fitting a bridge doctor to remove the stress on the spruce .Then I may fit seven new braces to give it a chance of a new life.I have one tiny brass plane with a flat sole that has never been used . This is where it will shine . I have the leftover outline wood from a violin I made .It will be very happy with that quality . Even though the sound was not right there was something that gave me hopeful hints of better things to come . This guitar will be my test bed for a shorter scale and another unequal temperament .The intonation was almost identical to my Mexican requinto . Miles out but the requinto just sounded nice .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Tue Feb 07, 2017 4:06 pm

Overnight the idea of the Bridge Doctor has become more appealing. I have a number of choices . Simply heat up the glue and fasten the two loose braces. One of them would make a poor matchstick . It would break before you lit it .That would leave a sagging belly and a nervous existence with low tension strings . But the Bridge Doctor seems to allow many new possibilities .Most of the youtube demos fail to clarify that there is no contact between the Bridge Doctor and the back . That`s very important.The sound of a guitar would be changed too much if there was a direct contact. The contrasting designs between guitars and bowed instruments becomes very interesting with the bridge doctor. The violin /viola /cello/double bass all rely on a Vertical activation with a thin bridge making little effect on the belly from a twisting action on the belly wood .Guitars rely on Horizontal activation . The bowed instruments need a sound post to provide a fulcrum combined with a vertical rocking action by the bridge foot . That gives a pumping movement to the top and bottom halves of the belly plate. ( I have been reading Mr Simogyi`s articles ). The bridge doctor controls the forces twisting the top downwards . But it may be too solid as it stands at the moment .The solidity comes from a direct contact with the solid end block. If it rested against a pliable vibrating surface it could have a similar effect to the violin sound post. That would create interactive vibrations and more tone .
If the (bridge doctor ) solid block and solid post leads to a stong but pliable cross bar before it reaches the end block we have a better chance for more tone .
If the bridge doctor is fitted it might make the width of a guitar bridge unnecessary . The section outside the string area will be damping vibrations . Also the idea of two slots or soundholes becomes possible for more vibration. More and maybe too much if you can`t stop it ?
The plethora of brace designs and patterns must give us a clue that we have not reached the best or final solution yet.
Violins have the problem in dry conditions of shrinking wood and string pressure on the sound post causing stress and distortions in the vibrating plates. In damp conditions the plates swell and this sets up the opposite sresses on the plates . There is an ideal violin sound post pressure which gets thrown out of balance. In a guitar there is no (easy or difficult ) adjustment as if we had a sound post to adjust . But now we have bridge doctors .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Wed Feb 08, 2017 11:05 pm

On a closer inspection there are some telltale splits along the edge of the 2 centre braces. Only about 1 1/2 inches from the centre cross bar. But the splits are in the top surface .The brace did not come unglued .Somebody must have lost their balance and put their hand out to save themselves and heard a loud crack.
Chipping away the loose section of the brace released the end with a thin section of the top still attached. Luckily I found a squeezed out blob of glue near the sound hole which gives a handy forensic clue to the rest of the guitar. I think every guitar should have a squeezeout blob left for future generations . One alternative is to fit a bridge doctor without replacing any braces just to see what it sounds like. .Then relax the strings and see how it brings the top back into shape. In case there is any hidden cracking in the top I might fit a set of Tatay style braces. He added a cross piece with a set of short braces where the splits happened .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Sat Feb 11, 2017 2:30 pm

The important thing with this guitar is not to force anything . With a broken piece of the belly pulled away ( narrow 1.5 ins long and 1/16 deep ) the accident would not have settled back in the best position so it had to be repaired first .The bridge doctor seems more suited to steel string guitars with larger forces to combat. I will let the new braces stiffen up the surface without any need to stress the wood . One more damaged brace to go . Who used the most braces in their guitars I wonder . Esteso seemed to use a lot .
I had to sand the inside edge of the sound hole to save it scraping my wrist .
Several checks with the lamp are needed for this shaving down job . So far no scratches anywhere .
With a light inside pressure using a wood screw and some wooden pads the top comes dead level without any bulge between bridge and hole. A ruler along the top shows exactly straight and a carpenters square compared to the square edge of a steel ruler at the side of the bridge shows it all lines up. The odd part to me is the rise (side to side ) at the end block. That has not been altered so it must be a part of the design to build in some stiffness .
One item I forgot was the bridge. As the old strings came off it fell out in 2 pieces. Thickness was 2.3mms. Measuring the slot gap shows 2.9 mms. New bridge bone and nut on their way in the post .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Sat Feb 11, 2017 11:49 pm

The bass side central brace was shaved down bit by bit .As it got thinner another loose section lifted away . No force required. So that brace was disconnected for 5 1/2 inches. The glue held a thin strip of the top .Only about 1/16 th inch again .If it had been hot fish glue it might have just sprung away and been refixable .Replacing the braces will be easier than taking them out . After I shake out the shavings I can still hear a faint rattle near the bottom end. This is like mending clocks. The reason will no doubt come to mind overnight . Patience is a virtue .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Mon Feb 13, 2017 2:21 pm

The longest braces have been removed now .Obviously the damage was caused on the bass side of the top .When I switched the room light out with a lamp inside the guitar aimed at the end block I could see a chink of light coming out. That`s in line with the pressure of the accident. I looked at that because there is a hairline crack in the varnish at the lining level . I don`t want the bother of heating the edge up as I have never done that type of repair before . So I will cut away a section of lining to check the contact between side and top . The lining looks a bit scruffy there and I won`t be re-using it anyway . The braces concealed their lack of adhesion very well so the same will have happened at the edge .It won`t be resonant with hidden cracks . The internal linings are continuous strips with cuts so not such a wide glue surface .
If I was going to offer new builders any advice I would urge them to use any white glue they like for construction but only use hot hide glue for the braces. If Torres was right the top "and the braces" need to be resonant. Pressing a blunt point into a lump of squeezout shows it has a rubbery feel compared to hot hide glue .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Tue Feb 14, 2017 4:51 pm

The lowest section of top edging was cut away and revealed nothing unglued but clearly showed the top is laminated . The outer surface is minutely thin and the thicker centre is quite soft to cut .Almost like balsa wood . That means the top grain direction mainly runs sideways . The 5 1/2 inch strip that was pulled away inside under the brace was just the lower outer surface .
Shifting a damaged brace through the sound hole is difficult because the part near the hole needs to be cut backwards towards the hole .Getting a grip with one hand is almost impossible. There must be a special tool for that .
It will be an interesting exercise to fit new braces . At the end of the day a new all wood top is a possible step forwards . Doing it all without creating damage is good practice for me .
In the plumbing shop last week they had a small screen and a flexy probe to peer inside things . That would be fun to work with.

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Wed Feb 15, 2017 8:27 pm

Silly detail time. When shaking out the shaved off braces I tried to understand what was making a rattle after the bits had fallen out . When I wrapped cling film around the unused tuners the problem was solved. But the sound seemed to come from inside the bottom of the guitar. A long way from the tuners .So Aria have used a very light inner layer of wood between thin layers of spruce for vibration and a measly 4 braces in a very tough type of wood that I would not recognise as resonant. The wobbly grain line was only on the end of one brace. Why not have super perfect braces with all dead straight grain for a measly 4 ?
The top is only a few thou low in the centre so looking at the Tatay brace pattern which uses a cross piece (ladder brace style)I could regain some shape across the top and see if his bracing makes a nice sound. Tatay guitars have a mixture of tones ranging from ladder braced Lacote to genuinely traditional Spanish and on a few rock and roll videos his guitars seems to shine there too. That is surprising and fascinating .
Just clearing away the ends of the old braces I am wondering what shape of surface will be there for gluing on the new braces. I shall test with a stick and some blue tack covered in cling film.I don`t want the glue to be a filler if I can avoid it .
Some hot hide glue strips to solidify the original torn out section will give me a clear conscience . Then I will use Titebond to position the new braces . Centre cross piece will be tilted to favour low and high notes and avoid wolf notes.
The trouble is I lay it flat with a diode lamp inside and an inspection mirror to see how far I have gone and avoid damage. When I cut away the braces the guitar is on it`s side on the table. But fitting new braces the sound hole will have to face downwards . I wonder what contortions that will involve .
Vibration patterns in a solid wood are generally about 4 times faster along the grain than across the grain . So what will they be with a cross grained mixture in a laminate . Maybe braces are more important than the vibrating material in that way .Irish lightweight boats (curraghs ) had a criss cross frame and a layer of canvas covering that with no floor planking but they still floated .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Thu Feb 16, 2017 11:23 am

A note about the outer edging of the guitar .I noticed a hairline crack running along the bottom edge between top and sides.Nothing was loose when I cut away the lowest section . But there was such a fine line where a glue line would have been I may have shaved a bit lower than I should. What it showed was a laminated side as well as top. The sides show the outer grain lines running in the normal direction so the inner layer of laminate was vertical and not horizontal . So the glue joint was holding an edge strip long grain to an end grain inner surface. Once again the outer surface is minutely thin . To replace the section I removed I will use a polyurethane glue such as Gorilla glue which is more successful as an end grain glue .
There are no worries about fancy dan purfling on this lightweight model . All the edge is simply coated with a black varnish line . It`s wider than any joint too. The varnish / lacquer (or paint) overlaps onto the top by about 1/8th inch .It keeps the weight down if nothing else . Lacquer would be a bit pricey for this one .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Fri Feb 17, 2017 10:18 pm

I was in two minds about a JLD bridge doctor but the strings have been off long enough for the wood to change back to flat if it was going to . So it needs to be straightened out . If l lay the guitar flat on the table the reflected image of the lampshade between soundhole and bridge is much larger than the lampshade image between bridge and guitar bottom .
Annoying are all the sites with different prices and ridiculous postage charges. I nearly paid for one but it added VAT right at the last minute. So I kicked that one into touch .E bay just does what it says .
The wood inside is clear enough now but a bellied surface would give a bad result for gluing and sound . I coated the areas where the braces had torn away with hot hide glue to stabilise them. I will avoid using those strips.Fortunately the four original brace positions make that easy .
The bridge doctor post will rest against a small end block which is only about one inch wide . That will allow some vibration and less damping . The diagram showing how this works makes it look as though it touches the back brace. That`s not the case .
I could make one myself but the screw action keeps it neat and simple .Let them get some reward for a good idea .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Mon Feb 20, 2017 11:27 pm

One thought about the bridge doctor. It has one fitting which uses the pins already in place as a fixing. That string position is not at the centre between strings like the screw version . The screw version is always shown in a central position .If you had x-ray vision you would notice a screw fitted ther would cut right through the central brace. Also the wooden block part would need a groove to avoid pressing on the brace. A ticklish positional deision is needed to avoid internal damage .
The slow first attempt at clearing all the braces via the soundhole produced an excellent idea . The braces Could be removed using a small brass plane but a new method surfaced yesterday . It may be well known already but here was the trick .I used an old Sheffield steel chisel for this job .The bevel makes the cutting impossible either way up because the harmonic bar is in the way . So I made a thin bevel on the back of the blade so it would cut along the surface with the original bevel upwards. The trick was to use a diamond file to round off the corners and polish the metal corners so it would slide along the surface if the chisel tilted off the brace . That little gem was worth the slow progress. All this was out of sight and the brace could be sensed by sliding the chisel end sideways until a bump was felt .That was the brace to be cut .Apart from that the chisel handle needs some tactile indicator to let you know for certain which way round the chisel is facing .
So all the space is now clear and I have to fit the bridge doctor before the braces otherwise I`m trying to glue to a distorted shape . Choosing the right glue and fitting the braces upside down before clamping ( I have to make the clamps out of plywood-)-then quickly turning it over to minimise dribbles seems to be a way out of the puzzle.
Lamination used to sound like something a bit tough and strong but this one seems too delicate to imagine ever swopping tops.
I wonder if luthiers ever put their reputations on the line with laminated guitars .

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Mon Feb 20, 2017 11:30 pm

I had my first official warning this week .I mean it was a really cheap guitar but the little message got through "You don`t need any more .You`ve got quite enough already ".I mean how cruel is that?

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Wed Feb 22, 2017 12:00 am

The new bone bridge arrived and was carefully sanded down till it fitted snugly.

amezcua
Posts: 329
Joined: Tue Oct 04, 2016 9:50 pm

Re: Low end Aria renovation

Post by amezcua » Wed Feb 22, 2017 3:27 pm

Today the Bridge Doctor arrived . I was curious to see if the instructions were as confusing as some buyers said .
There was a paper slip in the package asking "Did you know we have a forum?" That is http://www.btnmusic.co.uk/community Well the written and also internet instructions are confusing because the explanation diagrams label the large screw adjuster screw as the Tension Screw. But the written instructions mentions the Adjustment Screw. It`s the one that moves the spruce post too and fro .Basic stuff but liable to confuse .
The instructions for the classical guitars are mixed up with the guitars that use Pins to hold the strings. It keeps switching from one to the other .
Read all this next part after you have seen the internet site ( por favor ).
There is a small countersunk screw included .The narrow threaded part needs to be fitted first. When you countersink a screw hole the top of the screw will sit level with the surface.But they provide a decorative spot to cover the screw head. So you need a different shaped drill bit to sink the hole deeper at the same diameter so the decorative dot will fit .The internet diagram shows a Panhead screw with a head that is flat on top and underneath not a countersink shape. Laughably a picture of the drill needed is shown and it`s a nasty old rusty thing. Dear me .It needs a Panhead screw sunk below the surface for the decorative dot .
Fot the classical screwed in fitting they remember that most guitars have a brace at the centre and tell you to avoid drilling through the brace by shifting it sideways and filing a groove in the plastic post top. Very good. But they forget to mention the wooden block part that also contacts the guitar top . That piece of wood is twice as wide as the nylon post. So if you do not file that to avoid the brace it will not sit straight.It will be tilted sideways and also endways. (But ) If you don`t file the nylon post it will only tilt sideways and maybe bend the metal screw with the decorative dot.
Some pictures of the B D look as if the screw that fits through the top is not 100% vertical to the wooden block. I must have some German or Japanese genes as I had a close look at the shape of the block itself. I had to shift the holding screw to fit the narrower bridge and the hole is indeed not drilled vertically. So looking at the wooden section that also touches the top I noticed that "that " is not 90 degrees square across either and tilts in the opposite direction .The flat area of the wooden block that has three possible hole positions drilled is also slightly tilted but not as much as the top section . That was a Huge few mms out of whack .
Fortunately for me I have removed the braces already and originally there were only 4 so none were on the centre line . To recap the reason for complete removal of braces. I could feel some looseness in both inner braces but while shaving them away it was clear that the accidental pressure on the top area had disconnected one brace by 5 1/2 inches. So why would I trust the others to be intact? The other brace was disconnected by over 2 inches .It does not show up clearly by sensing a slight looseness at the end .
General reaction to the explanation sheet that comes with the Bridge Doctor is "disorganised and confusing ".
But still a very good idea that needs some close attention to the sequence of instructions .
When I fit this and find it works I will feel like Stan Laurel beng described as Oliver Hardy`s closest friend and severest critic . Don`t give up on it .
Last edited by amezcua on Fri Feb 24, 2017 12:11 am, edited 1 time in total.

User avatar
attila57
Posts: 382
Joined: Mon Nov 05, 2012 12:46 am
Location: Budapest, Hungary

Re: Low end Aria renovation

Post by attila57 » Thu Feb 23, 2017 9:12 pm

I once had an Aria flemenco guitar with laminated back. In fact it was one of my student instruments. I had bought it second hand. I was never completely satisfied with it. I replaced the saddle and the nut with custom bone pieces and planned to put on a new fingerboard, too. In the end I got fed up with it, and decided to disassemble it for lutherie study purposes. When I took it to pieces, I was shocked to find scrap quality boards and papier maché end blocks, not to mention the tons of thick PU lacquer, which was impossible to remove in any way. I'll keep its remnants for ever to remind me never to buy such an instrument...

Attila
Music to hear, why hear'st thou music sadly?
Sweets with sweets war not, joy delights in joy...

William Shakespeare, Sonnet 8

Return to “Luthiers”