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  #121  
Old 04-17-2021, 05:44 PM
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warfrat73 warfrat73 is offline
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I went and had a look at it, and (just as you said) the back is pulling the sides out of alignment... the taper built into the back edge is being transcribed into the top edge.

I flipped it back so that the top is down again, and it only takes a small amount of pressure at the neck block (as in, I can do it with my thumb) to get the top edge flush and tight with the work surface. I can see it flexing at the waist.

I'm thinking I could use a big clamp or two to (gently) pull the sides back into alignment while I glue in the linings, and then actually glue the top on with the whole assembly facing down, since it shouldn't take much pressure.

I haven't braced the top yet, so I can just go ahead and make it flat, that's not a big problem.
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  #122  
Old 04-17-2021, 06:40 PM
charles Tauber charles Tauber is offline
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Adding linings to the sides will add a significant amount of stiffness to the sides. You will still be able to clamp the end blocks inwards, but it will take a little more force. Checking the amount of thumb pressure required before and after adding the linings will provide you with some insight as to how much stiffness the Linings add. (if you used solid linings, you would not have very much give and probably would not be able to effectively squeeze the ends in.)

The main challenge will be getting the linings planar so that when you flip the assembly upside down and clamp it to the face down top you get a good glue joint between the linings and the top. It might take a bit of fiddling to figure out how much to squeeze the ends so that you get a clean or surface of the linings.
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  #123  
Old 04-18-2021, 05:12 PM
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Well, I may be snookered on this.

I tried a couple of things today. The best I could come up with was shimming the neck and heel block... I don't actually have a clamp long enough to span that gap, though I could certainly go buy one.

With the shims I can get a flat board to lie flush from the neck block to about 2-3" in from of the tail block, the gap opens up there to about 1/8", maybe a hair more. And there's enough gap at the waist that light comes through.

I guess I could put a bit more pressure on it, I could force it more. But I feel like I'm risking breaking it... but if it's a lost cause, what's the loss.

Annoyed, and frustrated, but less than I thought I'd be.
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  #124  
Old 04-18-2021, 05:46 PM
charles Tauber charles Tauber is offline
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Bindings are like moldings/base boards: they cover gaps where things don't meet.

What is most important is that you can get the geometry of the top right - not distorted to fit a wonky side assembly. As long as the linings are planar, and the gap between sides and top is small enough to be covered by binding and purfling, you'll be fine. While not ideal, even if the glue joint from top to linings isn't perfect, the glue from the bindings will keep everything together.

So, the trick is to make sure that the top isn't distorted when it is attached to the side assembly. I'm not sure that any method is perfect, but what I'd probably do is to use the dowels to make the equivalent of an outside mold. Push the side assembly, back facing down, into the dowel arrangement, adjusting the dowels until the gluing surface of the sides at the top is as close as it can be. I'd then attach the linings, leaving them proud of the sides, if necessary, so that the linings can be dressed level/planar.

One method for making the linings planar is to take a piece of plywood or MDF that is larger than your guitar and attach 80 grit sandpaper to one side. You can then rub back and forth the plywood piece, 80-grit side against the linings while it is still in the dowel/mold. Use a pencil and mark the gluing surface of the lining and blocks. When all of the pencil marks are gone, its planar. You can then turn the side assembly over and glue it to the face-down top.

I think you now understand first-hand why it is important to have fixed references/data for assembling components, as well as, for some methods of assembly, to attach both linings, then the top, then the back. It's important to work through what assembly sequence you are going to use and what references will be used in placing the components during the assembly.
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  #125  
Old 04-18-2021, 08:19 PM
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Yeah, I think I do understand that now. Like I said, I saw all those people using mold attach the back first, and thought... well, I'm sort of using a mold, so it's the same thing. Lots of learning happening.

Anyway, I went and actually measured, and the gap at the heel block is closer to 1/16" than 1/8", and I could probably bring it in a bit tighter than that.

I have the "large sanding board" set up that's integral to the Cumpiano method uses... that's actually what I was using as a reference flat surface.
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  #126  
Old 04-20-2021, 06:38 PM
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Feeling a bit more optimistic about being able to salvage it.

Got the top lining glued in over the last couple of days. And then spent about half an hour and got it very nearly flush, except for about a 1/16" gap at the heel block. I'll spend some more time with the sanding board tonight or tomorrow. And I think I should be able to get it darn close.
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Last edited by warfrat73; 04-20-2021 at 07:28 PM.
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  #127  
Old 04-29-2021, 07:42 PM
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Had some unexpected time to work on it tonight.

Had made several attempts to make my own rosette. Thought I might use some maple that I cut down a couple years ago, and maybe dye it to give a splash of color. I tried to bend some, but that didn't work very well, then tried cutting wedges and gluing... but found it pretty fidgety and figured I'd rather be working on other things. So I ordered a herringbone one from Stew-Mac (I signed up for the Stew-Max shipping thing, so I'm all for getting my money's worth by ordering small things).

Was a bit nervous about cutting the channels. I bought one of those dremel router bases and set that up. I sank a drill bit into my work surface and am using that as a pin to turn it on. I took two passes, seemed to work fine. And then it occurred to me that it had been raining for two days and I should probably check the humidity... well, my basement was up to 69%, though it had been hovering between about 45-50%.

And then I walked away to let the dehumidifier do its work.

I'm strangely proud of myself for realizing that.

I've managed to get a good flat gluing surface for the top after a fair bit of work with the sanding board.
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  #128  
Old 04-30-2021, 02:05 PM
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Well, the RH in the basement was back down to the low 50s today, being that it was only a quick blip up, I went ahead with it today. Stepping back and looking at it, that outer ring seems to be pushing out closer to the sides than is ideal. But it's done now.

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Last edited by warfrat73; 04-30-2021 at 02:40 PM.
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  #129  
Old 04-30-2021, 08:13 PM
JonWint JonWint is offline
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Quote:
Originally Posted by warfrat73 View Post
I bought one of those Dremel router bases and set that up. I sank a drill bit into my work surface and am using that as a pin to turn it on.
Why isn't there a hole in the center of the rosette for the pin you mentioned above? How did you guide the router?
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  #130  
Old 04-30-2021, 09:34 PM
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warfrat73 warfrat73 is offline
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There's a hole there. It's just small. But that was the size of a hole in the guide on the router base. I think my results would have been better with something thicker... that drill bit was a little bit flexible.
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  #131  
Old 04-30-2021, 09:40 PM
phavriluk phavriluk is offline
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I'm pleased whenever I encounter someone who starts a building project with a learning attitude. I knew nothing about lutherie and I found, like I think OP has, that the only way to learn is to do.

Gotta start somewhere.

Enjoy.
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  #132  
Old 04-30-2021, 10:08 PM
mirwa mirwa is offline
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Quote:
Originally Posted by warfrat73 View Post
There's a hole there. It's just small. But that was the size of a hole in the guide on the router base. I think my results would have been better with something thicker... that drill bit was a little bit flexible.
Your build is looking great and something to be proud of

Steve
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Last edited by mirwa; 04-30-2021 at 10:41 PM.
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  #133  
Old 05-01-2021, 08:27 AM
JonWint JonWint is offline
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Quote:
Originally Posted by warfrat73 View Post
It's just small. But that was the size of a hole in the guide on the router base. I think my results would have been better with something thicker... that drill bit was a little bit flexible.
The pin on mine is about 1/8" dia. I use a section of old countertop for rosettes. A solid setup.

[IMG][/IMG]
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  #134  
Old 05-01-2021, 09:33 AM
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warfrat73 warfrat73 is offline
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I'm sure it's a better system than what I'm using, but the Stew-Mac router base and rosette cutter are about a $200 investment at current prices, the Dremel base was about $20.

The only real problem ran into was that, at one point, the cutter blade came loose in the collet and got bound up a bit, taking an uneven cut. The was user error. I guess, as I suggested before, I think that I got a slightly uneven cut at times when the drill bit I was using flexed a bit, which isn't the most horrible thing in the world... just need to fill in a couple of gaps.

The other problem is that the minimum cutting radius with the included base is about 2.5", so I've had to drill a few holes in the acrylic base, which isn't really a big deal. The hole on the guide is about 5/64", but could definitely make a new guide for it with a bigger diameter hole.

If I stick with it, I'll slowly pick up some more specialized tools.

But, as it is, I've acquired well over $1k in tools (bandsaw, drill press, planes, chisels, clamps , rulers, etc.) over the last 3 months, which is way more than I meant to spend... but, I'm also not at all surprised.
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"What have I learned but the proper use for several tools" -Gary Snyder

Bourgeois DR-A / Bowerman "Working Man's" OM / Martin Custom D-18 (adi & flame) / Martin OM-21 / Northwood M70 MJ / 1970s Sigma DR-7 / Eastman E6D / Flatiron Signature A5 / Silverangel Econo A
(Call me Dan)

Last edited by warfrat73; 05-01-2021 at 09:43 AM.
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  #135  
Old 05-01-2021, 06:54 PM
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Got the top braces glued up. Might get them carved tomorrow. But I have some actual real work that needs to get done.
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"What have I learned but the proper use for several tools" -Gary Snyder

Bourgeois DR-A / Bowerman "Working Man's" OM / Martin Custom D-18 (adi & flame) / Martin OM-21 / Northwood M70 MJ / 1970s Sigma DR-7 / Eastman E6D / Flatiron Signature A5 / Silverangel Econo A
(Call me Dan)
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