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What is the best way to index the top with the sides and neck to accurately place it on the box?

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Mark Ewing
Columbus Ohio
"Trees are an important and precious thing. We should build good things with them. Building good guitars with heart are the best use for them." K. Yairi.

Mark I place a pencil mark on the center lines of the top on the end grain and line this up with the center lines for the rim. On the mortise side you can place a piece of tape across the mortise and mark the center on the tape.

Once the kerfed linings are routed out for the braces and if you mark your routes with the top properly centered on the rim the braces inlet into the kerfed linings will help hold your top or back in place too.

I do it a little different than Hesh. I use a couple of locating pins in the excess area of my top that pin the top into the proper position using holes in body mold.
There ya go 2 options with more to come I sure.

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Jim Watts
http://jameswattsguitars.com

Jim my friend on Martin tops I see little handles over hanging the waist area and they have holes in them. Is this to pin the top to the mold? Is this how you do it? Thanks

I am building my first one from scratch and when I got to the place where I glued my top (which I did today) I really struggled with getting it positioned in the right place. I was stumped by the asymmetrical nature of the body. I kept trying to get it square and had no place to reference. I also struggled with the location of the sound hole from head to tail block but I'm convinced now that that was of little concern and that what really counts is location of the bridge.
Looking around on the net revealed, ala Charlie Hoffman, that he puts three little index hole/pin locators under the fingerboard but I think he said it was for locating the braces.

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Mark Ewing
Columbus Ohio
"Trees are an important and precious thing. We should build good things with them. Building good guitars with heart are the best use for them." K. Yairi.

I have been collaborating on a complete system for some time now with someone we all know (and love) and I have not really shared any of this up to this point -- really in the hope to wait until I get all my ideas up and running before I let the cat out of the bag.

And I have to say... the person I am collaborating with on this (who at this point wants to keep his head down) has really done much of the heavy lifting. I come up with the ideas and he does the heavy lifting. So, I want to give credit where credit is due. Without him none of this would have happened.

But this question really segues nicely and I can give a preview.

This is my plate jig. It has a center line and 3 holes with 1/4" drill bushings. 2 that drill index location holes in the plate, and one that helps locate the center of the sound hole.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

You get the idea here.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

This corresponds to a mold with registration pins in it.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

You are saying.... "so what?"

But wait... there's more....

Also as part of this system there is a 15' radius dish with locating pins for back braces. (I set my braces before I install the back center seam. I have a custom miter box to cut all the pieces and jig to locate that too, but I didn't take a pic of that.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

And the 2.0 verson of the mold has a couple new features.

Here is an attachment that will locate a trim router to help you perfectly notch the back braces.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

And if you notice, the 2.0 mold has 4 location pins so additionall attachments can be added during the construction phase.

** Some things that are in the works is a back profile layer so the sides can be bent unprofiled, then cut to profile with a lam trimmer and a cutter blade on a custom base.

** A Somogyi style tapping mold clamp

And a couple of other ideas I am noodling with.

Essentially, I have been spending a lot of time thinking about the "PROCESS" of building a guitar from the top down. My intention has been to knock out a lot of the time invested in standardized items increasing first the consistancy, and second the speed of the build.

And secondarily I believe that this will give me more time to work on the finer points of construction.


... again, none of these ideas are revolutionary in and of themselves (and you are really just seeing one facet of a bigger plan) but it seemed relavent to the discussion.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

Brock, your mold looks like it has finger joints at the tail end? Also a pin below the top locator pin. Does that pin hold your mold together.

Great Idea's, I've been thinking of all the same things just haven't gotten around to implimenting any of it.

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My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

Yeah, the mold has two mating halves and a pin (not the locating pin) holds both parts together rock solid. When you want to break the mold down you just pound out the pin.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

That's an excellent idea Brock, mind if I borrow it?

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My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

Go for it.

The only thing I would ask is that nobody produce these ideas commercially. I am pretty sure the guy I am working with on this is going to offer some of these things commercially, but I just don't think he is ready yet. He has put up with my constant haranging that it seems like it is the least I can ask on his behalf.

But you are free to borrow any of these ideas you like for your own amusement.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

Hesh,
I think that's what those holes are for in the martin tops. Don't know though for sure.

Brock - This is very similar to the way I do it. My holes are in about the same spot as yours. They're easy to trim off when placed here.. You can cut your top net this way also, making binding easier. You'll like your new system Brock.

You can see my locating holes in this top photo.

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Jim Watts
http://jameswattsguitars.com

I do something similar to Jim. Instead of indexing the tab of the top on my mold, I glue a small block of scrap spruce centred on the neck block/tailblock ends of the side/rim. Centre your top (or back) and temporarily clamp with a cam clamp then drill a round toothpick sized hole through the top into the scrap wood. When you go to permanently laminate your top use a round toothpick to register the top in the correct location.

That's what I do for my Archtops as I route my neck block mortise after the top and back is glued on. For a flattop, instead of gluing a scrap piece of wood at the neck block end you could drill a hole through the top into the neck block as it will be covered with the fretboard extension later.

Once everything is dry, the scrap wood easily comes off with a little encouragement from a chisel.

Very interesting stuff, guys.

I've also been in the process of re-evaluating the entire build process and have been designing my own method to streamline the process while improving final results.

Your little preview looks pretty promising, Brock. Similar in ways to mine, different in others. I'm a toolmaker by trade and do CAD work and CNC as well, so my plan is to develop jigs, fixtures, templates, moulds etc. that will quickly produce most of the parts accurately enough that they'll more or less go together like a jigsaw puzzle.

I'm hoping to have the system making instruments by the end of the year.

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-Clint Beacock

I do it just like AnthonyZ. I think I got the Idea from a John Calkin article in American Lutherie.

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Matt Jacobs

"Don't tase me bro"

I route an opening in the neck block before I glue it in to match an insert in the neck. I then glue a little spruce piece to the top which fits in this slot for alignment. It gets routed off when the pocket is opened up. If none of the top braces are tucked sometimes I do a similar thing to the heel block, usually just a little 1/8 shim. Brock, your setup looks really cool, but I would guess you would have to be really really sure of all your specs before going that route. I am still always changing little things depending on the wood.

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Burton
http://www.legeytinstruments.com
Brookline, MA.

Thanks Matt, John Calkin's GAL article is where I picked up the tip.

Good stuff. I'm rigging up to do the same. I'd like to see the finer details. Accuracy in the jigs is crucial if your pockets in the rims are to be clean when you rout them to match the braces on the back or top.