Official Luthiers Forum!
http://www-.luthiersforum.com/forum/

The Coral Snake
http://www-.luthiersforum.com/forum/viewtopic.php?f=10130&t=34382		 Page 1 of 2
Author:  DennisK [ Sun Nov 27, 2011 8:58 pm ]
Post subject:  The Coral Snake
I've been meaning to start this thread since I started the guitar a couple weeks ago, but at least I have a buffer of updates now :) Current state is all plates thicknessed and neck blank glued up, but here's how it starts.

A couple months ago, Brian/oval soundhole posted this thread about an interesting little guitar made by our old friend Torres. What really got me was the fact that it has no bracing at all in the main vibrating area around the bridge... except for the bridge itself, of course. Naturally, I wanted to give it a try and see how it sounds.

Some more interesting bits about the guitar are that it uses a lute style bridge with only a tie block, no saddle, it only has one brace across the back (though a rather large foot on the headblock), the sides are ultra thin, averaging 0.8mm, and it utilizes a fun style of linings; a thin strip of softwood that can be crimped instead of sawing kerfs to allow it to bend around the curves.

A lot of things about it didn't make me especially happy, so I've decided to take the inspiration and build as I like, rather than doing a straight up clone. The overall dimensions will be more or less the same, but woods and guts will be different. Mine will have an A frame from the headblock, passing under the upper cross strut, and joining at the lower cross strut. Strong and elegant. There will be no headblock foot, but I will add a second ladder brace at the upper bout on the back. Sides will be 1-1.5mm, plus reinforcements to prevent the splitty nightmare seen in the photos. Top will be attached with dentellones rather than the crimped linings, just because I like doing it that way. There will be no spruce in this build. All bracing is redwood. This is an experimental build, so I might as well experiment here and see if redwood braces splitting are really a concern (this is flamenco, so I plan to beat the [ship high in transit] out of it :mrgreen:). Also, it will have 19 frets instead of 18 (this puts the lower cross strut a touch closer to the bridge, but worth it).

First things first, draw up the plans. Estimate the measurements from the photos on that web site and the couple dimensions they gave, mark on paper, and doodle a shape. Then trace half of it and cut it out to be the master template, and use that to make a side bending pattern.
Attachment:
Plans.jpg


Next is the fun part, a safari through my wood closet to pick out some nice (but cheap, as this is an experimental build) stuff. Here's what I ended up with (I'd already cut the top halves to shape in the first shot):
Attachment:
Wood.jpg

Attachment:
Redwood.jpg

Redwood top: Free! Bonus with some others I bought. It had a thin spot and a scruffy spot. Put the thin spot in the soundhole, scruffy spot outside the pattern, and a bunch of offcuts for use in bracing later.
Honduran rosewood back/sides: $60, from a crazy good deal on ebay.
Spanish cedar neck: $2 from Hibdon's second grade sale a couple years ago.
Bois de rose fingerboard: $30 from Gilmer. Expensive for this build, but it felt right for it.
African blackwood headplate: $10 (or was it $15?) from Sniggly. Actually using a different one than this pic (but from the same batch).
Mulberry bridge: Free from Ernie [:Y:]
Bindings and backstrip: Camatillo rosewood from LMI: $16
Rosewood tuning pegs from LMI (not pictured): $12

So I'm up to about $140 so far, plus a little more for inlay, bracewood, nut (remember there's no saddle!) and frets. So much for making it a $100 build.
Author:  fingerstyle1978 [ Sun Nov 27, 2011 10:33 pm ]
Post subject:  Re: The Coral Snake
Looks interesting, good luck with the build.
Author:  DennisK [ Mon Nov 28, 2011 11:10 pm ]
Post subject:  Re: The Coral Snake
Ok, on to some real action. Step 1, join the plates. Jointing was surprisingly painless. However, I did get to cheat a bit on the back since it was longer than necessary, and one of my main issues is a gap at the end where I start the plane run. So, I let there be a gap and the rest of the joint is pretty good. Then the glue-up, using the tape method, plus various clamps to apply more pressure and hold it flat.
Attachment:
JoiningBack.jpg

Attachment:
CutOut.jpg

Then thin 'em down...
Attachment:
ThinningTop.jpg

Attachment:
BackSmoothed.jpg

The redwood planed quite beautifully. Big pile of fluffy shavings, and it's about .090" thick. Hopefully I haven't gone too far. This is my first classical, and first time working with redwood, so I don't have much to compare to. But it still feels pretty stiff, and with the small size, slightly shorter scale, a bit of dome, and straight pull bridge with strings 1/4" from the surface, I think it'll be ok. It's extremely light weight, just 75 grams.

For the back, I ended up flipping the pattern around from what was drawn on the set when I bought it. It was already a parlor set, but this guitar is even smaller so I could use the narrower end for the lower bout, putting that little knot just outside the waist. It planed relatively well with my toothy blade. Some tearing, but not too bad. Switched to scraper once I felt like the deepest tears were about as deep as I wanted to go. It ended up around .060-.070" thick, and 200 grams.

Then I decided to add a back strip, since the joint wasn't quite flawless at the ends. Just went with a simple strip of camatillo to match the bindings.
Attachment:
Backstrip.jpg

I probably should have done this before thinning it, as the fresh glue separated the center seam for a few inches from the tail eek But thanks to the magic of hide glue, it was easy to close back up again after the strip was dry. Just flip it over, dump some hot water on it to soften the glue, and apply gravity clamps, with a ruler to distribute the pressure :)
Attachment:
FixingBackSeam.jpg

After that comes the sides... these were a lot of work to thin down. For one thing, the plane didn't agree with some knots on them (probably had something to do with the fact that I don't remember when was the last time I sharpened it :?). Major tearing, so I switched to scraping pretty early on. Luckily the scraper that came with the Veritas scraper holder takes a much better burr than my old one, so I was pulling up shavings that were actually crispy, rather than fluffy. However, I could get bigger shavings using it directly than I could with the holder... which led to a couple small blisters. Oh well. Here's the back and sides thinned down.
Attachment:
BackSides.jpg

Looks like the body is going to be under 500 grams. Hopefully I can get the neck light enough while still being strong enough, that it isn't too neck heavy. This thing's gonna be a feather :)
Author:  DennisK [ Tue Nov 29, 2011 10:44 am ]
Post subject:  Re: The Coral Snake
Here we go with the last post of catching up! After this, I will look as slow as I really am.

Time to prepare the neck blank. Unfortunately I forgot I was planning a photo documentary for a while, and didn't get shots of cutting and gluing the scarf joint. It was pretty boring anyway, just mark the angle, chisel along the line to give the saw a groove to start in, and saw it freehand. Then stack the pieces, plane the angle surface mostly flat, and glue 'er up. I didn't even bother with the crazy contraption shown in the Cumpiano book this time. Just a couple cam clamps, with wax paper and a cork lined block on the headplate surface. Hide glue grabs well enough that it doesn't slide under pressure, plus it doesn't matter if it slides a little bit since I'm just going to plane the headplate surface flat again.

After that's done, I can make some measurements to see where the 12th fret ends up, laminate a heel block, and glue it on:
Attachment:
GluingHeel.jpg

I hate the look of stacked heels, but I also dislike waste, so if I have any rift/flat sawn pieces of the same wood as the neck blank, I like to laminate vertically so the grain makes a V down the heel:
Attachment:
LaminatedHeel.jpg

I finally got some of the 3M mylar backed PSA sandpaper used for the Scary Sharp system, and resharpened my block plane with it. Quite effective. I think the harder backing material helps keep the edge of the blade from getting a microscopic rounding over like regular wet/dry sandpaper. The sharpness made it possible to flatten the surfaces of everything quickly and precisely, even as small as the heel block halves, which I've never managed to do before. This build has yet to be touched by sandpaper bliss

Next up, the headplate. More missed photography. I had a pretty goofy looking setup going to joint the bookmatch. Two neck blanks clamped together, with the headplate halves inbetween. Then plane away, and glue it up by tape method and squeezing together by hand for a minute while the hide glue cools. After that I went to thin it down, using my newly developed technique for thinning small things that I can't get a grip on to plane: Clamp one end to the bench, and viciously attack it with a chisel :lol: Just peel up chips all over the place, and try to keep it relatively even. Then turn it around and get where the clamp was blocking before, and finally scrape it smooth. Much faster than using a scraper from the beginning :) However, in this case it occurred to me I could glue it to the neck before the scraping, so I did:
Attachment:
GluingHeadplate.jpg

Quite beautiful after scraping:
Attachment:
Headplate.jpg

Then gave it a swab of shellac to keep it clean and pristine. Here it is with the headstock template. It's a paddle headstock with friction pegs, so I can use my normal steel string shape. This is a smaller version for a smaller guitar, but with a wider bottom for the 2" nut. Notice the careful cutting of the bookmatch joint to put sapwood stripes on the sides of it, thus keeping with the coral snake color theme of yellow borders between black and red parts :)
Attachment:
HeadstockPattern.jpg


I also planed the fingerboard down some. The fresh surface is gorgeous dark burgundy with black ink lines. I wish it would hold its color, but it oxidizes to mostly black. On the other hand, that makes it a good replacement for ebony, while being lighter weight (similar to Honduran rosewood by my measurements) and likely much more stable. It smells delicious. Unlike any other rosewood, and second only to Brazilian. I would call it a mix of roses, apple pie, and honey. I wish it was more plentiful and sustainably managed :(
Attachment:
FingerboardBlank.jpg


And now, it is time to start the long and not so pleasant process of cutting pieces for the rosette. Bloodwood, African blackwood, and African blackwood sapwood for the stripes, with a black mother of pearl eye.
Attachment:
Rosette.jpg
Author:  DennisK [ Mon Dec 05, 2011 2:54 pm ]
Post subject:  Re: The Coral Snake
Finally! The snake is ready to inlay.
Attachment:
Rosette.jpg

Haven't cut the black MOP eye yet, but I'll do that when I'm cutting the headstock logo... maybe tomorrow after the tendons in my left hand recover from holding all those little bits while filing them to shape. Tough work getting them to match width precisely at the joints, and correct angles. Came out a little narrower and shorter than the drawing, but that's ok. I also shortened the length of the black/red segments to add one more red where it meets the fingerboard, because the fingerboard will have yellow binding and it continues the whole color theme.

Here's a fun trick I used to double my output on the black segments. The blackwood pieces were way too thick anyway, so instead of thinning them down, I just cut pieces and then sliced them in half using a razor saw.
Attachment:
Slice.jpg


Sad thing is, I think the bloodwood was originally thick enough to do this as well, but I hadn't come up with the idea yet, and went to the trouble to thin it down before cutting any pieces, thinking I'd be saving time after inlaying them since it's tough to chisel down significantly over-thick inlays without stabbing the top. Oh well, it'll still save time on future bloodwood inlays that don't have duplicate pieces.

I also drilled the tuning peg holes, and reamed to fit:
Attachment:
Pegs.jpg

For the record, the expensive peg reamer from LMI is definitely worth it. Cuts effortlessly, plus is big enough to ream for closed steel string tuners instead of needing a drill press.

Now let's see if I can get that snake in there all nice and gapless.
Author:  DennisK [ Sun Dec 11, 2011 10:49 pm ]
Post subject:  Re: The Coral Snake
Ok, after much distraction and procrastination, the inlays are done. I probably should have come up with a more jiggy way to make the snake (i.e. more like a regular radial rosette, using oversize tiles followed by a circle cutter), but this way I could use the tiny bits of African blackwood sapwood from the headplate offcuts, align the grain of each piece to make a continuous circle rather than radial grain, and taper the thickness of the snake from end to end, which is quite a pleasing look. During the routing of the channel, I ended up filing quite a few pieces to fit the angles together perfectly, thus shortening the snake a bit more. And since the last red section was long already, I decided to just shorten it even more and add another yellow and black tile before it goes behind the fingerboard. Yet more cutting, but worth it as it also allowed me to get the bottom center black piece perfectly centered so it's all nice and symmetrical looking.

Here are all the pieces ready to glue. I numbered them just incase, but fortunately I never scrambled the pile so they ended up being unnecessary.
Attachment:
SnakePieces2.jpg


After that I set up my shell cutting station and made a little black MOP dot for the eye, and cut the headstock logo. I forgot to take a picture of the actual cutting, but this is pretty much what it looks like.
Attachment:
ShellCutting.jpg


The little trench routed into the cutting table (mostly covered by the sandpaper) was for an idea to have a continuous water drip running on it, funneled to a drain, but it turns out that dipping my fingers in the water bowl and letting it drip onto the paper towel as I cut works just fine to keep all the dust contained. Needle files and sandpaper are also kept wet while finetuning pieces.

Here are the completed inlays.
Attachment:
SnakeInlay.jpg

Attachment:
LogoInlay.jpg


Next up, roughing out the neck and slotting the fingerboard.
Author:  DennisK [ Thu Dec 15, 2011 3:40 am ]
Post subject:  Re: The Coral Snake
Lots of pictures today! Headstock is pretty much done.

First, cut the neck to tapered width, just a touch wider than the fingerboard will be. Then coping saw the headstock (a bit nerve wracking in the tight curves at the top, but it went very well), and start chiseling the transition area.
Attachment:
HeadstockRough.jpg

I don't have a solid procedure for this... just shave until it looks about right, and aim to get the lip of the handstop underneath the nut area for maximum strength. Although this time, I planed the neck shaft blank to thickness before scarfing the headstock, so the back is all beautiful and continuous wood, rather than being half end grain and then a scarf joint line before getting to the continuous grain. Also means it's naturally super strong, so the handstop is really only there because I think it looks cool and feels good, especially when carrying the guitar by the headstock.

I also did some rasp and needle file work to the headstock outline to iron out the coping saw marks, so the sides are smooth and mostly symmetrical now.
Attachment:
HeadstockRefining.jpg

Then more chiseling to taper the thickness of the headstock (nice thing about friction pegs is they don't need a fat, constant thickness headstock). Spanish cedar is a joy to carve, and I have to be careful not to peel off too thick of shavings, especially as I approach final thickness and try to flatten it as much as possible. Then out comes the scraper to flatten out the chisel marks. Except... the peg holes made it go not so evenly, and things quickly ended up being a wavy mess.
Attachment:
HeadstockWavy.jpg

After a few failed attempts at targeting just the high areas to even it out, I got mad and attacked it with 60 grit backed by a cork lined block for flattening the upper part, and a fat dowel in the curve up to the handstop, and a lot of the time just my thumb. This guitar's sandpaper virginity is lost :cry:

Then I got out my trusty Big Scary Looking Gouge to hollow out the handstop area a bit. Gotta be careful not to cut through the scarf jointed headstock wood!
Attachment:
HandstopHollow.jpg

Some more scraping and sanding, and it's pretty well done aside from the transition to the neck shaft, which can't be finalized until I'm carving the shaft, which cant be done until after the fingerboard is on so I can really feel the shape, which can't be done until the body is assembled.

The thickness tapers from maybe 7/8" at the handstop, to 3/8" at the end. I think I'll trim the pegs shorter, as they look a little excessive at the moment.
Attachment:
HeadstockFront.jpg

Attachment:
HeadstockBack.jpg

Attachment:
HeadstockSide.jpg

Tomorrow will be the heel, and after that I can get to bracing and side bending and finally close this baby up.

I doodled some layout lines on the heel, so I can sleep on it and make sure it's what I want to do.
Attachment:
HeelLayout.jpg

I don't see the point of having a big square heel block inside, when it really only needs to be as wide as the outer heel to hold the sides in place. Not being one to follow tradition without knowing why, I'll try it my way and see how it goes. I'm also not doing a headblock foot... or tongue extension. Mostly for weight, but also because the foot complicates heel slip resets with the length and angle change and body taper and resulting gap between it and the back. Always seemed backward to me that the foot is traditionally only used on integral necks, precisely where it causes the most difficulty if a reset is ever needed. So, instead of those things, I'll be using A-frame style braces, notched into the headblock and underneath the upper cross strut and ending at the lower cross strut on the top, and from beside the heel to the upper cross strut on the back (thus not blocking the heel from slipping forward incase of reset).

And on the topic of weight, one of my goals for this build is to break the 1kg barrier. All the parts together are presently 1.2kg, but the fingerboard alone should be losing over 100g, and neck probably another 100+, and the bracing shouldn't add much, so I think I'll be under by quite a bit. It would be pretty crazy to do it in cypress with padauk fingerboard, rather than Honduran rosewood and bois de rose :) Bet that would cut another 200g. But then it would probably be neck heavy.
Author:  DennisK [ Sat Dec 17, 2011 12:49 am ]
Post subject:  Re: The Coral Snake
Heel complete!

First saw the slots. I used my trusty ryoba saw freehand, then drop a scraper into the slot and saw again to widen it out. They're quite thin, which is because the sides are super thin. I ended up taking them down a little more, to approximately .045", or just over 1mm. They're still surprisingly stiff, should be plenty strong once bent to shape and with reinforcements to prevent the splitty nightmare of the Torres guitar.

Then coping saw the curve of the heel, and start violently removing material (always careful that even a slip will not risk cutting myself)
Attachment:
HeelRough1.jpg

Attachment:
HeelRough2.jpg

Attachment:
HeelRough3.jpg

I use the ryoba saw, coping saw, 1/2" chisel, and 3/4" violin knife to do this. Again, not much of a procedure to it. Cut to the lines drawn on the wood to start, and after that it's just the vision in my head.

Many shavings later, the rough shape is complete.
Attachment:
HeelRough4.jpg

After that, I went at it with the rasp to iron out the knife marks, and then sandpaper 60 grit through 1500. I think I'll give it a swab of shellac, as I'm hoping not to touch the actual heel part of this again, lest I have to sand in the corner of the heel and the sides.
Attachment:
Heel.jpg

And here you can see the cool V grain from the vertical lamination of the heel block. I love this style, for the looks and because it's a great use of reject neck blanks.
Attachment:
HeelGrain.jpg

Tomorrow... splitting brace stock and making dentellones. And hopefully I can get to side bending as well, as it's not going to be too cold outside (I bend on the porch for fire safety and space), and I like to do it ahead of time so they can get all their anger worked out and back to moisture equilibrium before I need them. Then touch up immediately before gluing to the top.
Author:  nyazzip [ Sat Dec 17, 2011 2:00 am ]
Post subject:  Re: The Coral Snake
i'm growing increasingly curious about making a smaller bodied classical style guitar...based on my love for a cheap Suzuki nylon string i picked up a few months ago; it sounds so wonderful.....
regarding those "heel slits", is there any way that could be done on a table saw or something, while stock is still flat/square/etcetera? thanks for the posts
Author:  DennisK [ Sat Dec 17, 2011 3:14 am ]
Post subject:  Re: The Coral Snake
Indeed you can. I've just seen too many woodworkers with missing fingers to want one, when I can hand saw it in a few minutes anyway (although it would be more accurate). You may want to make your heel block the full width of the neck so it lays flat on its side. As you can see in the heel layout photo at the end of the previous post, mine does not. On the upside, laying tilted on the narrower heel block would angle the slot a bit so the connecting wood is wider at the top. That reminds me, I forgot to mention that mine is significantly tapered, so the connector is 1 1/8" wide at the top, and 1/2" at the bottom.
Attachment:
HeelTop.jpg

It always scares me when people have a tiny sliver of wood holding it all together. Granted, 1/2" all the way up would be plenty, but the more the better I say. Doesn't take a very deep slot to keep the sides in place.

Also, make sure the slots are a tight fit for the sides. Mine don't fit at all right now, actually. But I'll thin down the ends of the sides after bending and trimming, so they wedge in a bit. Don't want a gap between the heel and the side. Another option is to cut wide slots, and use separate wedges of some sort inside to press the sides against the heel end grain surface.

And I would highly recommend building one of these, considering how much fun it has been so far :) Depending on how this turns out, I may do another (I'm thinking milk snake theme). One thing I'd like to do different is use a 45 degree riftsawn top. This one is perfectly quartered, and thus very stiff across the grain. Since normal classicals have a thinner top with fan braces stiffening along the grain, I figure this one will have a disproportionately stiff cross dipole. So, by using a top that is sawn to minimize cross grain stiffness, it should be more similar to the normal stiffness distribution.
Author:  DennisK [ Thu Jan 05, 2012 11:44 pm ]
Post subject:  Re: The Coral Snake
Ok, moving along on this build some more for the moment. I'm working on retopping another, hence the delay, but with a couple days of warm weather, I figured I might as well take advantage since I do my side bending outside, and get this baby closed up. I was hoping to get the sides glued to the top today, but wasn't quite fast enough. Still need to make dentellones and tail block. Oh well, I've got another shot at it tomorrow.

One thing though... a few days ago, I knocked the soundboard off a shelf, and this happened gaah
Attachment:
TopCrack.jpg

Attachment:
TopCrack2.jpg

It was a funny thing... I had a bunch of plates all leaned up together, and picked up the front one, which created a vacuum as it pulled away from this one. Most plates probably wouldn't have moved, but this one is so light (75g) it flew right up.

On the bright side, the crack being wedged open like that made it easy to get fully coated in glue before slipping it closed. All better now.
Attachment:
TopFixed.jpg
Author:  DennisK [ Thu Jan 05, 2012 11:44 pm ]
Post subject:  Re: The Coral Snake
Ok, on to the actual update. First up, the back bracing. Upper cross brace with A frame, in place of the huge headblock foot in the Torres guitar. Just seems better structure to me, not to mention a lot easier to do a heel slip reset if it's ever needed. Probably heavier than the foot, but not by too much. The A braces are notched into the cross brace for maximum rigidity. There's one more cross brace half way between the first one and the tail block, in a similar location to the original's. The other two strips are very thin, only there as crack catchers.
Attachment:
BackBracing.jpg


For the top bracing, I decided to include an interesting idea from this guy http://www.pjguitar.com/website/classicalguitars/features/rising_neck/rising_neck.html
A thin cross grain patch underneath the headblock. Somewhat reminiscent of the popsicle brace on steel string guitars, but seems more effective being linked with the headblock and rims directly, where the shear force often distorts things over time.
Attachment:
CrossGrainPatch.jpg

Then glue the braces... notice there's another one of those crack catchers underneath the bridge area. Not thick enough to really affect stiffness, but hopefully will help to prevent the crackled mess that the original had become. Those strips are made from offcuts of the top, which was oversize for this little guitar. No photos of gluing them, because I was too lazy to come up with any more sophisticated way to clamp them than to just sit and hold it down with my fingers until the hide glue was tacked up enough not to go anywhere :P
Attachment:
GluingBraces.jpg

Then carve them up... the A braces are notched underneath the upper cross strut, so they run all the way from the headblock to the lower cross strut.
Attachment:
BraceCarving.jpg

Then notch the headblock for the A braces:
Attachment:
HeelNotch.jpg

Attachment:
BrokenNotch.jpg

Oops :oops: I was afraid this would happen, and it did. Oh well, it made the notch a lot easier to cut :lol: I glued it back on later. Not quite the beauty of keeping it solid, but I don't think anything bad will happen.

I wish I'd thought to cut the headblock ledge for the soundboard thickness before gluing those A braces to the top. I ended up having to work down the depth of the ledge and notches at the same time, which is hard to tell which of them is actually hitting and needs deepened. Eventually I got it, and then glued it down. Again, just pressed it down by hand for a few minutes to set the glue. This is one of the things I love about hide glue; you don't need to make fancy clamping setups for most things. Then set a brick on it to make sure it doesn't go anywhere while it dries the rest of the way.
Attachment:
GluingNeck.jpg

So, that's it for bracing, except for trimming the ends once I get the sides bent. I also need to do one of my famous painted labels on the back at some point before closing it up. Current weights are 93g for the braced top, 217g for the back, and just over 200 for the neck. Then another maybe 200-250 for the sides/linings/bridge, and 150 for fingerboard, it looks like I'll be well under my 1kg goal :) Hard to say whether it will be neck heavy or tail heavy just yet.
Author:  DennisK [ Tue Jan 10, 2012 1:02 am ]
Post subject:  Re: The Coral Snake
Next step, make a tail block. I used a scrap of Spanish cedar from a previously made neck, which was not quite wide enough, but twice as thick as I needed. So, I sliced it in two and joined the pieces together. Actually was big enough that I have a spare block for the next one :)
After a bit of planing and sanding, it looks like this. Not too heavy at 16 grams.
Attachment:
TailBlock.jpg

And here's a shot of my dentellone factory. I made them from the offcuts of the redwood top.
Attachment:
Dentellones.jpg

Cut, split, sand. Wide ones are curved on the surface that glues to the ribs, skinny ones are flat to go in the waist area. Half are flat on top to go in the upper region, half are angled to try and coax the lower bout into a slight dome.

Then the long and difficult task of side bending. I hope it gets easier in the future. Fortunately the warm weather held, so it was enjoyable work at least. After a few hours I got them pretty closely matched to the pattern, although they may be scorched enough that it won't scrape out. Can't go too much deeper when starting from 1mm thickness :) They are remarkably stiff and stubborn though, even at that. Really doesn't feel any different than 2mm mahogany on a dread size guitar. Also, notice my failure to make them perfectly bookmatched... they're offset from eachother by about 1 inch along the length, so one has more of the top end trimmed off, and the other has more of the tail end trimmed off. Oh well, it's only visual. These sides were way over length for a guitar this small, so no trouble there... yet.
Attachment:
BentSides.jpg

Then trim the ends to length, trim the soundboard braces to length, and glue into the slots.
Attachment:
SidesGlued.jpg

Now here's the trouble. The bass side one actually just barely reaches its slot, due to a bonehead move copying the cut from the first one onto it. I forgot to account for the fact that the cut is angled because the heel's connector is wider at the top than the bottom, and that the angle mirrors from one side to the other. So, I cut it angled the wrong way. Fortunately, I had the sense to make it 1/4" too long, test, and then finalize, so I was able to make it work. Makes the body just a touch asymmetrical, but that's ok. Hand bent sides assembled totally freestanding will never be truly symmetrical anyway.

Then, glue to tail block, and start gluing dentellones. I used my fingerboard radius sanding block as a caul for gluing to the arched tail block. It's not a perfect joint, as the tail block radius is a bit tighter, but it'll do.
Attachment:
GluingDentellones.jpg

I actually got too sleepy to wait for the tail block glue on the first side to fully dry, so I finished the next day. All nice and pretty. Notice the spaces left for side braces. I'll glue those in after I get the sides tapered.
Attachment:
DentellonesDone.jpg

Sadly, the dream of a perfect seam at the tail continues to elude me. My cuts were flawless, perfectly straight. But the second one slipped when I was getting it clamped. Maybe if I had a few more hands to hold onto the side and keep it from springing back away from the tail block I could do it, but trying to keep it from moving using downward pressure while getting the caul in place and manipulating the clamps one handed, doesn't seem to work very well.
Attachment:
TailJoint.jpg

So I guess I'll be doing a tail wedge of some design. Could go super simple and just use another little strip of the binding like is on the back, but I don't think I can stand to do it. Must as least make a wedge of some other wood, bordered by half width binding strips. But I'll worry about that when I get to the binding step.

This box poings like nothing else when tapped. I can't wait to hear it together with the back when I get it closed up. It's also incredibly light weight. Just under 500 grams in its current state. Another 200 for the back, and maybe 200 for fingerboard, bridge, and tuners, and I'll still only be at 900. Gonna be a joy to play, it is :)
Author:  nyazzip [ Tue Jan 10, 2012 2:12 am ]
Post subject:  Re: The Coral Snake
Quote:
Maybe if I had a few more hands to hold onto the side and keep it from springing back away from the tail block I could do it,

..yes, that would be referred to as a "mold" :lol:
anyway thanks for all the pics. what does your bending rig consist of...?
Author:  DennisK [ Tue Jan 10, 2012 2:27 pm ]
Post subject:  Re: The Coral Snake
nyazzip wrote:
Quote:
Maybe if I had a few more hands to hold onto the side and keep it from springing back away from the tail block I could do it,

..yes, that would be referred to as a "mold" :lol:

A mold, you say? Molds are for people with brains. Real doofuses consider them an unnecessary a waste of material.

But maybe I'll try an adaptable mold sometime (where you have slots in from the edges of a workboard, and bolt dowels onto it along the outline of the guitar in question).

Quote:
anyway thanks for all the pics. what does your bending rig consist of...?

Hey, I'm glad at least one person is following this thing :)
And dang it, I didn't even think to take the camera out and document the whole bending process. Would have been interesting to watch the sides bend and twist back and forth as I shifted the curves forward and back to approach the line. Oh well, next time.

Anyway, here is my setup. A scrap of 3" exhaust pipe free from a muffler shop. Drilled holes in it and bolted to a scrap of 1x12 with L brackets. Electric charcoal starter for the heat source, squeezed in a vise until it just fits in the pipe. Cheap dimmer switch to control temperature. Also my glue pot, because there wasn't enough space to get it out of the shot :P And the bending pattern, which is just a couple sheets of paper taped together and the shape traced on both sides.
Attachment:
HotPipe.jpg

Notice the 3 prong to 2 prong converter on the charcoal starter's plug, and the label on its heatsink that says only use on a grounded circuit. Unfortunately this house has no grounded circuits, and the wiring is so old that it would be more dangerous to mess with it at all than to just leave it alone, unless we do a total replacement of the wiring. No zaps yet at least, and I screw it down to the front porch for use, so at least if it starts a fire it will be on the outside of the house, and thus more likely to be put out before the whole thing burns down. Also might work to pound a metal pole down into the dirt and wire the converter's ground tip to that.
Author:  nyazzip [ Tue Jan 10, 2012 3:09 pm ]
Post subject:  Re: The Coral Snake
those brackets look a little lightweight...are you able to put some force on them? only thing i have tried to bend thus far were some maple violin sides, using a pipe in a vice with a propane torch perched below to blow into it. not very ideal. i think i am going to look for a charcoal starter. i would be inclined to think there is a good chance the element might break though, when bent, i think it is a very brittle/high resistance alloy they use to make them. gladly i have a 10 amp variac so i should be good there.
i can totally see not wanting to build a mold, especially if you think there's a chance that you won't be using that design much/ever again, down the road. looks like severe tedium cutting out all that plywood.
cheers
Author:  DennisK [ Tue Jan 10, 2012 3:36 pm ]
Post subject:  Re: The Coral Snake
Those brackets are more than enough. It feels very solid, and no way could I bend a bracket or pull a screw before cracking the piece of wood I'm bending. The 3 black screws that attach it to the porch are more questionable though, since I've stuck them into the same holes many times, so they're bound to loosen eventually. But when that happens, I'll just move my spot over an inch.

As for bending the charcoal starter, breaking the element is a definite possibility, especially if you use a smaller pipe. Mine didn't need much bending to fit. I would like to have a 1-2" pipe for tight bends though. The waist on this was pushing the limit of what I can do. This one is great for the wider bends though, and being a fairly massive, thick walled pipe means the temperature is reasonably stable.

One interesting technique I've heard for charcoal starter bending, is to plug it in and get up to full temperature to soften it before putting the pressure on (but unplug it before pressure, incase it does break). More dangerous working with hot metal, but you could probably get it into a 2" or smaller pipe before breaking it that way.

I've also heard of using hair curling irons :) Definitely would work on binding/purfling and violin sides, but maybe not enough power to bend full width guitar sides. I've also used a pan on the stove to bend purflings when I was too lazy to get out the hot pipe.
Author:  DennisK [ Wed Jan 11, 2012 10:47 pm ]
Post subject:  Re: The Coral Snake
Side braces are all in. I hate gluing those little suckers. Pain to get clamped, and I can only do two at a time due to the clamps running into eachother (and the number of appropriately sized scraps I had lying around to use as cauls). Also have to wait an hour or so for them to get 100% dry, because I clamp them tight to squeeze the slight ripples out of the sides from bending the interlocked grain.
Attachment:
GluingSideBraces.jpg

I love cam clamps for their ease of use and deep reach, but the bars are long and heavy so they have to be balanced like this when hanging on to a thin side with no support, and thus the inward pointing bars run into eachother. A rigid outside mold would make it a lot easier, although I only have enough clamps for 4 anyway. I think I went a little overboard on the number of side braces, but I wanted a lot in the lower bout area where I won't be able to reach later, to prevent, or at least catch any cracks that get started down there due to the super thin sides. Although they feel quite strong and not crack-prone anyway. Notice that 4 of the side braces double as feet for the cross struts.
Attachment:
SideBraces.jpg

I also did the label painting. Just gotta get all the back linings glued between those braces and this baby will be ready to close up :)
Attachment:
LabelPainting.jpg
Author:  DennisK [ Sat Jan 14, 2012 1:43 am ]
Post subject:  Re: The Coral Snake
Lots of fiddly work today in preparation for box closing. Kerfed linings are all made by hand, using more of the top offcuts, and just jabbing into it with a chisel to make the kerf. Pretty tiring work actually, even on this very soft wood.
Attachment:
GluingLinings.jpg

Then trim the top overhang. Done with my trusty Hock violin knife.
Attachment:
TrimmingOverhang.jpg

Also a little block plane and scraper work to flatten the area under the fingerboard extension. This was slightly not flat, and even slighterly above the level of the neck plane. Just a few feather thin shavings.
Attachment:
FlatteningUpperBout.jpg

I also carved the side braces mostly away. Just didn't feel right having those big square pillars all over in there. I like them better being thin and rounded, mostly just crack catchers, but a little bit of stiffening, and tapering up to full size at the ends to act as dentellones. Also carved the linings to be more triangular/rounded tops (the back linings, not the top dentellones which were already triangular).
Attachment:
CarvedSideBraces.jpg

Then trim the back to shape. I wish I had a better way to do this. I just hold it on the body, trace around with pencil, and then coping saw to about 1/8" outside the line. But the saw splinters the wood sometimes, and in the past I've actually split the outer edges off of plates with the stress of the sawing. This time I just got a couple splinters that may go inside the binding, but probably not, and will probably be leveled out by rounding over the linings if they do.
Attachment:
BackChip.jpg

Then test fit the back...
Attachment:
BackTest.jpg

All looks good. If John Killin is following this thread, check out your spool clamps in that shot :) They're great.
After a bit of tapping on it, reading Somogyi book, and pondering, I decided to carve the back brace down a lot.
Attachment:
BackBrace.jpg

Nice smooth arch, about 1/2" high in the center, and 1/8" at the linings. Box taps better after carving, although it's hard to tell anything by the tap at this point since the spool clamps damp out the edges a bit, and add a lot of mass to the sides.

So, all set for closing now, except for that I hadn't checked on my humidity in a while and it was down to 18%, with the top being slightly squiggly from contraction. Back up to 30% now, which has been my working range for this build since it takes a large amount of water to maintain even in my tiny curtained shop area. For the past few days I've been refilling the humidifier just before bed, and still wake up to unmeasurably low RH. Top has mostly flattened back out already, so I think I'll give it another half hour or so and then glue 'er up.

I'm actually going to leave out the back brace feet and back binding until after the initial string up and settling in. I want to leave the back easy to remove, incase I have to pull it and add some fan braces. The bridge area is pretty squishy feeling, and this being my first classical I don't really have anything to compare to.
Author:  Jim_H [ Sat Jan 14, 2012 3:17 am ]
Post subject:  Re: The Coral Snake
Love this thread Dennis! Really cool stuff!
Author:  nyazzip [ Sat Jan 14, 2012 7:05 pm ]
Post subject:  Re: The Coral Snake
regarding a comment i made, well, i tracked down an electric charcoal starter for 10 bucks, heated it up, squeezed it in the vice(unplugged), and...it cracked, like i thought it might. didn't even get to light any charcoal with it!
grr! looks like i might have to pay big, huge bucks for a bending iron if i ever want to do this
Author:  DennisK [ Tue Jan 17, 2012 2:56 am ]
Post subject:  Re: The Coral Snake
nyazzip wrote:
regarding a comment i made, well, i tracked down an electric charcoal starter for 10 bucks, heated it up, squeezed it in the vice(unplugged), and...it cracked, like i thought it might. didn't even get to light any charcoal with it!
grr! looks like i might have to pay big, huge bucks for a bending iron if i ever want to do this

Dang, guess the heating trick doesn't help that much. What size pipe were you trying to fit it into?

I've been being a slowpoke the past few days. Really nice weather, so actually spending time outdoors. But progress has been made. Glued the back, which pretty much went according to plan. Then scraped the sides.
Attachment:
ScrapingSides.jpg

They cleaned up nicely. Turns out most of the darkness was just burnt resin on the surface, rather than deeper scorching. However, the ripples, while shallow in absolute terms, are still too deep to scrape out entirely without making the sides too thin. So, there will be a slight dip right along the middle of the sides. Oh well.

Then, after a bit of work cleaning up some poorly sawn and rough sanded camatillo rosewood bindings, and thinning them to about .06" (just scrape and eyeball it), it was time to cut the binding channels for the top. I would string it all up and see whether it survives without fan braces before doing this, but then I'd have to pull the fingerboard later to notch the binding into the sides of the heel. Might as well do this now, and the back binding after string up.

I decided to add a .02" maple purfling line as well. I'd originally planned on no purfling, but since the camatillo is dark, I figure better to add a light line separating from the red in keeping with the coral snake color pattern :) So, I have my gramil set for about .08", or a tad less, and with the blade on the curved side of the body so it can navigate the waist.
Attachment:
BindingGramil.jpg

The maple is the same height as the binding, so there will only be one ledge, no separate binding ledge. Ideally, when cutting the ledge with a gramil, you want the binding to be the same thickness as the sides. That makes life much easier since you just split the side away from the linings and you're done. But since these sides are thinner than I'd want the binding to be, I'll be cutting into the linings anyway. Therefore, since it's only one thin purfling line, it's not worth the trouble of a second ledge. The dentellones are rather small and fragile though, so every bit of depth cut into them increases risk of breaking it. Proceed with caution.

So, the first score marks are made. Start at the wide part of the upper or lower bout and go with the grain, very lightly, and then gradually increasing pressure with each pass. After 4 or 5, it should look like this.
Attachment:
BindingScore1.jpg

Then continue the line up into the heel by hand with a knife. The notch is not full depth yet, just the soundboard material is chipped out.
Attachment:
BindingNotch1.jpg

If you can, score entirely through the soundboard. If not, chisel off to your score depth, and then score again until you make it through. At this point, you should have the tops of the linings and ribs exposed, and a nice clean and vertical edge on the soundboard.
Attachment:
BindingScore2.jpg

Before proceeding, I went around one more time to score into the tops of the linings. Not absolutely necessary, but makes the chiseling step later go a little more easily.

Then set the gramil for scoring into the ribs. This time it goes with the blade on the flat side of the gramil body, and my little spruce guide block taped to it. The guide block keeps the corners of the gramil from denting the top, plus puts the bearing surface right near the edge of the guitar, which is absolutely necessary for Manzer wedge guitars, but also helps with regular domed plates. The top on this one is nearly flat though, but I still used the block to prevent denting the top (or so I hoped...). When using the guide block, you have to have a good view of what you're doing, and carefully hold it parallel to the ribs so the blade contacts at the right depth and angle.
Attachment:
BindingScore3.jpg

I actually hold it with both hands for better control, but of course one was needed to hold the camera :)

For the most part, the guide block succeeded in not denting the top too badly. Just a slight impression in some places. But one spot, I snagged and pushed too hard, jamming the corner of the guide block into the softer redwood, resulting in this :cry:
Attachment:
BindingGouge.jpg

I'll try steaming it out, and scraping it some when rounding over the binding, but I'm guessing it will never be gone entirely. To prevent it happening again, I rounded over the corners of the guide block so they shouldn't dig in so much. I think next time I'll skip the guide block for the top, and instead round over the corners of the gramil itself so it can't dent anymore.
Attachment:
GramilCorner.jpg
Author:  DennisK [ Tue Jan 17, 2012 3:02 am ]
Post subject:  Re: The Coral Snake
Aside from that, scoring the ribs went pretty smoothly. This is the hardest wood I've yet attacked with the gramil, and required a bit different technique than usual. Same light and gradually increasing pressure to get the mark started, but to get any useful depth to it, I had to go back and forth repeatedly over a small distance, then move, and repeat, all the way around. Sort of boring, but got the job done.
Attachment:
BindingScore4.jpg

Then start splitting the ribs away from the linings. Got a nice long strip here. Usually it breaks sooner and you have to start a new one peeling. A few times, I went back to the gramil to deepen the score mark and get the rib to split off more cleanly.
Attachment:
BindingRibPeel.jpg

I broke one dentellone here. No big deal, but I might glue it back in later anyway.
Attachment:
BindingDentellone.jpg

After getting all the rib material cleared off, time to do one more round of scoring, this time into the sides of the linings. Gotta be careful not to go too deep and cut through the linings entirely!
Attachment:
BindingScore5.jpg

Then some semi-freehand chiseling to complete the channel. Keep the chisel vertical, and get right to the edge of the top and no deeper. Go back to the gramil and swipe back and forth at any areas that need the bottom of the channel flattened better. I actually had to wear safety glasses for this, because chiseling the hide glue on the linings was sending tiny fragments zipping all over the place :lol:
Attachment:
BindingChisel.jpg

Then finish up the notches into the heel. Just fiddly work with the violin knife, x-acto knife, and this mini-chisel I made out of a nail a long time ago. This would be a pain to do in a harder wood than Spanish cedar.
Attachment:
BindingNotch2.jpg

Then bent the bindings... or at least one of them. The other one was a bad from the get-go, cracked and twisted, but I tried to save it. After an hour of wrestling to close up the last couple gaps, I decided to give it up. I'll bend a new one tomorrow (or maybe day after, since an extreme cold front just came in, and I have no place to set up my bending indoors).

Here's the good strip, and its purfling (which is flexible enough it didn't really even need bending, so I just gave it a couple swipes over the iron to make it easier to deal with)
Attachment:
BindingStrips.jpg
Author:  oval soundhole [ Thu Jan 19, 2012 6:02 pm ]
Post subject:  Re: The Coral Snake
really liking this thread, hopefully I'll get around to building one of these guitars myself
Author:  alan stassforth [ Sat Jan 21, 2012 8:53 pm ]
Post subject:  Re: The Coral Snake
Hey Dennis, very cool build going on here!
I usually don't come to the docubuild section,
and did so by mistake and found this thread.
I just got one of those gramil tools,
but haven't used it yet.
I use a Sloane cutter,
(or violin cutter) usually, and want to use the gramil as the top cutting tool,
and the Sloane as a side cutter,
so I don't have to keep changing the blade depth.
Anyway, which end do you usually use to ride on the guitar?
Looks like the small extension from your pics.
When would you use the other longer extension?
Also, how do you keep it parallel with that block on there?
Page 1 of 2 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/