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Charity Acoustic


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Yeah, I though about doing it that way too. But the bearing on the StewMac router bit is maybe 1/4" thick, and the height of my binding channel is 0.2", so I was afraid if I did the binding channel first, there wouldn't be enough side material left for the bearing to register on. So for me it was purfling channel first, then change the bearing & drop the bit and cut the binding channel.

And even though I used CA, the purfling did swell outside the channel a bit. But not by much, less than a fingernail.

I'm wishing now that I installed the end graft before I cut the binding channel...easy enough to sand flush, but would have been easier to do it first.

Now on to the end graft jig... :D

Edited by erikbojerik
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Yeah, I though about doing it that way too. But the bearing on the StewMac router bit is maybe 1/4" thick, and the height of my binding channel is 0.2", so I was afraid if I did the binding channel first, there wouldn't be enough side material left for the bearing to register on. So for me it was purfling channel first, then change the bearing & drop the bit and cut the binding channel.

And even though I used CA, the purfling did swell outside the channel a bit. But not by much, less than a fingernail.

I'm wishing now that I installed the end graft before I cut the binding channel...easy enough to sand flush, but would have been easier to do it first.

Now on to the end graft jig... :D

Yep, the miters on the end graft are always a bit of special fitting for me. Unless you just run the binding with no fine lines and across the top and bottom unbroken. It all depends on how complicated you want to make it. One thing I have been interested in trying is inlaying shell into the sides. I just have not figured out what material is used(that micro thin shell for flexability?).

Good luck with it. I sounds like it is going great.

Peace,Rich

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I made up some spare purfling and left it un-bent, so I may try to do a mitered binding around the end graft.

I'm more or less happy with my miters so far; the purfling is ebony-maple-ebony (0.03-0.03-0.03), I worked pretty carefully with a razor blade and I can still see a thin line in the maple at the mitered joints. I'd rather there was no line, but it seems very tough to be able to hide the miter joint in maple binding.

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I made up some spare purfling and left it un-bent, so I may try to do a mitered binding around the end graft.

I'm more or less happy with my miters so far; the purfling is ebony-maple-ebony (0.03-0.03-0.03), I worked pretty carefully with a razor blade and I can still see a thin line in the maple at the mitered joints. I'd rather there was no line, but it seems very tough to be able to hide the miter joint in maple binding.

Maple miters are next to impossible to make completely invisable. I think it has more to do with color and figure in the Maple. I have been using a deadly sharp chisel to make my mitere. I tried with razor blades, but found the weight/length of a chisel helped me with control.

Peace,Rich

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This week, got an OK end-graft jig made up and did that. The router template for the end graft screws down into threaded inserts sunk into the work table, flush with the guitar's tail with the box held in place in a makeshift clamp using threaded rods screwed into inserts sunk into the edge of the worktable.

End Graft Jig

You acoustic aficionados will notice that I have the narrow end of the end graft pointing toward the soundboard. Yes this is backwards from "normal" and yes it was intentional, I couldn't find any structural reasons for doing it in any particular orientation, so just for kicks I decided to flip it and make that my "thing" on this one.

Here's the rout; 0.06" (into 0.09" sides) so I don't take out any of the purfling (already glued in).

End Graft Rout

So then on a whim I decided to go whole-hog and attempt a mitered purfling around the end graft. Here you see the purfling strips CA'ed in place and the outline of the graft in mac ebony.

EndRout2.jpg

The tricky part will be when I install the final binding which has the purfling for the sides already glued on and bent to shape...I'll have to trim the purling off the binding where it rides over the end graft, and miter it to the purfling bordering the sides of the end graft. :D Which means, for the best possible miters, I'll have to start the binding from the tail and work toward the heel... :DB)

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Did it. Amazing what a little patience and a razor blade will get you. Not to mention a magnifying glass. :D

EndBinding.jpg

It's all about those tight details baby. Looking great. I doubt most guys that have never done a fairly complex bit of fine line mitering and joining can appreciate just how tricky the details can be on an acoustic. It is really notable to those who have though.

P.S. I don't know if you have a chisel that you use for miters, but I keep a 1/4" and a 1/8" wide set that are deadly sharp and are only used for miters. Really handy.

Peace,Rich

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The binding turned out great! Very happy. Sorry no pics, I moved straight to the grain fill.

Going with an epoxy grain fill for the back and sides. I first put down a coat of spray shellac on the top, mainly to protect it as I worked the back and sides. It will be sanded off once the back & sides are levelled.

I'm using just 5-minute Loctite from Home Depot (the "professional" stuff in the 2 squeeze bottles, not the syringe stuff), mixing in large batches and applying with disposable plastic trowels. First coat went on fine, but I was still getting used to working it...it sets up pretty fast so its best if you work it correctly the first time. I eventually found it best to throw down a good-sized puddle and then smooth it with a wide trowel, then clean up the excess on the edges. :D The first application had lots of bumps & ridges in it because I used a small trowel. I levelled with 220 grit and by the time I was done, I had sanded through to the wood in about 50% of the guitar. So on went the second coat this morning.

I have to say, I LOVE the way this brings out the grain texture and chatoyance of the east indian rosewood. Yeah there's a lot of sanding involved, but I think the finish quality will be worth it once I get the clear on (still debating nitro vs KTM-9).

I am a little frightened about using epoxy on the soundboard though...once I sand off the shellac, I may just go with straight clear on there and fill the grain with a build-up of clear coat. Not sure yet.

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  • 4 weeks later...

The marathon epoxy grain fill session is now...thankfully...over. After getting the back and sides filled, I took the shellac off the top and now I will temporarily attach the bridge, string it up "in the white" and see how it sounds. Just from bonk testing, I suspect I will have to thin the top a bit more before applying my finish.

I've got poly on the headstock face, for resistance to string-up scratching. The rest of the neck will be Tru Oil.

I'm thinking nitro for the top, for ease of repair. But it will be several months yet before I can spray nitro outside.

Back and sides will be either nitro or Tru Oil.

Or, if I can get access to a cabinet making buddy's spray booth, I may just go with poly over the whole body, making sure to keep it thin on top. Only problem is, if the top gets dinged it can be pretty difficult to repair and make it invisible with poly.

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  • 4 months later...

Well....13 months after starting :D , this project is done!

Strung it up in the white....sound was good, it didn't implode, I was pretty happy.

Got some practice in with the new spray guns, and laid down 2 coats of pre-cat conversion varnish on the body, levelling with 400 grit in between. Neck is Tru Oil, headstock is poly.

After the second coat, it was hanging in the garage when an 800 pound gorilla got loose and found it.

finished.jpg

The idea behind the project from the beginning was to auction it off and donate the proceeds to my church. B) I guess I'll just write a check.

After making all the rookie mistakes on this one, I toyed with the bonfire idea. But now I figure I can use this one, and an old Fender Shenandoah body I have in the basement, to work on my repair skills. So stay tuned for the acoustic repair thread....Booyaa!

:D

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Erik, this is really a bummer. This same thing happened to me on my first guitar but I managed to fix it. The first sight of the cracks was pretty shocking (although the tone of the guitar when it hit the concrete was pretty good).

After looking back at the construction pics I want to mention something that might prevent this kind of damage int he future. I noticed the lack of side braces. These not only hold the sides together and make them stiffer, but they also prevent cracks from propagating past them. This would have kept the side piece from coming off completely and may also have kept the crack localized to the area that was hit (when my guitar hit the crack was only as wide as the braces were spaced). The way I do them is to glue them in all the way across the side grain before the kerfing so that the entire width of the side is supported.

I really hope you can salvage this and learn some repair techniques in the process. A lot of work went into this so far. It is possible to repair it and have it remain invisible. You might want to check out frets.com for some tips on how to go about it.

~David

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Oh man. Sorry to hear that Erik. I had a buffing accident(slipped right out of my careless hands) and my Snakewood/Quilted Sapele took a hard hit. I know the feelings, Shock, anger, sad, irritated, and then I had to get away. Couple days later I inspected the damage(looked repairable), but just have not wanted to touch it yet. Some days I feel like burning every guitar I have ever made and starting fresh(those little flaws are hard for me to deal with). I just can't bring myself to burn them even if they haunt me. I do think looking back at how I did things keeps the things that worked and didn't work fresher in my mind, so keeping them around if for that purpose only seems better than burning.

P.S. David makes a good point about side braces or even cloth tape to limit cracks.

Peace,Rich

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Yeah, I remember a thread (maybe here, or the MIMF) debating the merits of wood braces vs cloth tape. It was the first thing I thought of when the side piece popped....just one of those things that slipped my mind when assembling the box.

Luckily the neck was not on it, so I'll be putting on my repair hat and having a go at it.

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  • 1 year later...

OK - remember this one? I've kept it hanging around my shop, so I get a reminder every day - it finally got the better of me over the holiday break, so here we go again!

First - as a reminder to where we were over a year ago, it had an unfortunate interaction with the concrete floor of the shop:

finished.jpg

First step back to playability - rout off a little of the binding in preparation for removing the top.

repair1JPG.jpg

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CA to the rescue - the separated pieces of the rims fit together quite nicely, and glued up with CA with only a little bit of splinter-gap at the impact point near the treble-side of the tailblock.

repair7JPG.jpg

No pics for this, but the spliter gaps were filled with epoxy, and walnut side braces were epoxied to the inside of the rims.

A few days ago I reattached the top after re-sanding the rims in the radius dish - the tear-out of the spruce at the neck and tail blocks were patched up with epoxy and sanded flush with the rest of the top, and the cracks in the tail-end of the top were fixed with watered-down Titebond and a few cleats. I also took some time to scallop and thin the braces, as it was originally way over-braced. The upper ends of the X are let into the linings, while the lower ends of the X, and the finger and tone bars, are feathered down to nearly nothing at the rims.

Yesterday, I re-did the ebony-maple-ebony purflings and walnut binding strips, a little wider and deeper than originally to take up the slack from removing the top. Stuck on with CA and taped - clean-up today.

repair8.jpg

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Wow Erik. I read through this whole thread earlier today and was hesitant to reply, but I'm really impressed by the positive attitude you've kept through the whole thing, and the tenacity you showed in repairing it. Can't wait to see how it comes out.

-Dave

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That accident pic made me feel sick, and I shivered, especially after reading the grain filling section. I think if that happened to mine after all the work it takes to build an acoustic I would sit in a corner and unashamedly cry my eyeballs out.

It's good that your giving it another go well done

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