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  #31  
Old 08-06-2017, 06:55 PM
CabinetMan CabinetMan is offline
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Thanks Neil,
I got the neck block started today. Got the angle for the bottom on it and cut it to length and width. I believe I'll go ahead and cut the groove and drill the bolt holes for the neck to fit in before I glue it in place.

Also, May try and make some of the reverse kerfing out of poplar and see how it goes. I think the reverse has a MUCH cleaner look to it. Looks like you did and awesome job on yours.
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  #32  
Old 08-10-2017, 07:14 PM
CabinetMan CabinetMan is offline
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Well I've gotten a little more done the last couple days.
Laid out the Neck block then got it cut out.

20170807_192554 by Cabinet Man, on Flickr
20170807_200247 by Cabinet Man, on Flickr

Decided to go with a Laminated Cherry neck. Started with the rough lumber then Jointed , Planed and Glued up the laminations.

Once Dry, I Jointed and Squared it up. Made all the necessary measurements and marked off an outline of all the cuts to be made on the stock. I decided to go ahead and cut the tenon on the neck before gluing in the neck block to get a precise fit. I did allow for the thickness of the side wood.
The neck is now rough cut.
20170809_130655 by Cabinet Man, on Flickr20170809_132800 by Cabinet Man, on Flickr
20170809_134322 by Cabinet Man, on Flickr
20170810_080223 by Cabinet Man, on Flickr
20170810_123032 by Cabinet Man, on Flickr
20170810_153708 by Cabinet Man, on Flickr
20170810_162150 by Cabinet Man, on Flickr
20170810_164138 by Cabinet Man, on Flickr
20170810_164551 by Cabinet Man, on Flickr
20170810_171040 by Cabinet Man, on Flickr
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  #33  
Old 08-10-2017, 07:30 PM
redir redir is offline
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Looks like you got everything under control. How did you bend the sides?
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  #34  
Old 08-10-2017, 08:00 PM
CabinetMan CabinetMan is offline
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Redir, Thanks for the response.
I made a Hot Pipe Bender using some exhaust pipe a friend that owns a muffler shop gave me, Some sheet metal and a water heater element from a local hardware store. I control the heat using a Variac ( I think that's what its called, LOL) that someone had given my dad. Also put a piece of 3/4 ply to rest the sides on as I bend to help keep from twisting and traced an outline of a side on it to use as a refrence.
[IMG]20170802_131751 by Cabinet Man, on Flickr[/IMG]
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  #35  
Old 08-10-2017, 08:17 PM
CabinetMan CabinetMan is offline
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Redir, So I'm gonna go with a flat sound board. Since I have a good fit between the neck block and the neck tenon, I "ASSUME" that my neck angle will be correct? Correct?
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  #36  
Old 08-11-2017, 12:19 AM
dekutree64 dekutree64 is offline
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Quote:
Originally Posted by CabinetMan View Post
Redir, So I'm gonna go with a flat sound board. Since I have a good fit between the neck block and the neck tenon, I "ASSUME" that my neck angle will be correct? Correct?
It is preferable to have the headblock and neck top surface coplanar, but that alone won't create the correct geometry.

What is the target string height on your plan? (distance up from the soundboard surface to the strings just in front of the bridge). Typically it will be about 1/2" (12.7mm).

My magic formula is the fret plane projection should be 2-2.5mm below the target string height. (fret plane projection is where you lay a straightedge along the frets and measure the distance between it and the soundboard surface at the bridge location)

There are many ways to accomplish that. The neck angle, soundboard arching, rim profile, fingerboard thickness, and fret height all work together to determine the fret plane projection.

So for typical 12.7mm target string height, fret plane projection should be 10.2-10.7mm. To compare, a fully flat neck/soundboard with 6.3mm (1/4") thick fingerboard and 1mm fret height means your fret plane projection is just 6.3+1=7.3mm, which is a fair bit too low.

Put another way, for typical string height, a straightedge laid along the neck surface before gluing the fingerboard on should have a 2.9-3.4mm (about 1/8") gap under it at the bridge location.

As redir suggested earlier, arching the upper transverse brace and/or sanding an angle into the upper bout of the rim can give you the necessary increase in projection height. Or just angle the neck independently of the box and stick a wedge under the fingerboard extension.
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  #37  
Old 08-11-2017, 05:19 AM
CabinetMan CabinetMan is offline
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The string height on the plans I have is 5/16" to the bottom of the strings.
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  #38  
Old 08-11-2017, 06:32 AM
redir redir is offline
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Quote:
Originally Posted by CabinetMan View Post
Redir, So I'm gonna go with a flat sound board. Since I have a good fit between the neck block and the neck tenon, I "ASSUME" that my neck angle will be correct? Correct?
Great job on bending the sides, reason I asked is because they fit so perfectly in your mold.

No I would definitely not assume the neck angle will be correct. The goal is to have the string height 1/2in over the sound board at the bridge. So if you have a bridge that is 3/8th inch thick and a saddle that protrudes 1/8th inch then you have a perfect neck angle.

I'll show a picture rather than try and explain how I do 'flat' tops. If it's dead flat then you would have to have a thick fretboard to make that target goal string height at the bridge so there are a few ways you can accomplish that, one is below which uses an arched UTB and a canted (bent) top from the top of the soundhole forward (basically the end of the fretboard). The other way is to set the neck angle so that you get the right string height and then fill in any airspace under the fretboard extension with a wedge shaped shim.

This is my workboard, there is a shim made from balsa that is wedge shaped. I can't remember the exact thickness (I did the math a long time ago) but I think it goes from 1/8in at the head block to zero. That sets the proper angle.




And then also I arch the UTB. So between the arch and the canted top it essentially creates a ramp so that the line drawn from the nut to the end of the fretboard will continue till it just hits the top of the bridge. THen when you add frets and about a 1/8th inch saddle you get the proper string height.



Neck body geometry is something that gets very confusing. It took me a long time to figure out something that works for my method of building, which is the old schools style of using open workboards. You could also look into using radius dishes and how that geometry works as well. But it looks like you are building in a similar style and since you are building true flat you will have to work out something.

The shim method is perfectly acceptable and probably even easier really. Again all you need to do is get that angle right then just fill in the air space. The goal is to have a nice straight line from nut to bridge. IF you jsut tack down the fretboard extension then you will get too much fall away (another geometry concept) and a neck body joint hump.
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  #39  
Old 08-11-2017, 10:41 AM
CabinetMan CabinetMan is offline
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Redir,
Thanks so much for the info and pictures. I now understand what you are talking about.
Anything else that you see that will help me or give me a heads up on please do so. As my wife says about me, I can use all the help I can get, LOL.

I love my job of building custom cabinets but building this acoustic guitar is truly an enjoyable experience . I love learning new things.

Don't know how much I'll get to do this weekend but I'll post again as I get more done.
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  #40  
Old 08-11-2017, 10:44 AM
dekutree64 dekutree64 is offline
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Quote:
Originally Posted by CabinetMan View Post
The string height on the plans I have is 5/16" to the bottom of the strings.
You sure that's the string height and not just the height of the bridge without the saddle? If so, post a photo of the plan with a ruler on it because I won't believe it until I see it
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  #41  
Old 08-11-2017, 01:56 PM
CabinetMan CabinetMan is offline
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dekutree64, Here you go. I know my eyes aren't what they used to be but I know their not that bad, LOL.
2017-08-11_03-52-31 by Cabinet Man, on Flickr
I've heard that seeing is believing.
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  #42  
Old 08-11-2017, 02:23 PM
redir redir is offline
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Like most plans out there you can always find something wrong, that's wrong imho. Typically a bridge is made to 5 or 6/16ths inch thick. IS that plan a model of some vintage guitar perhaps? I guess it could be part of the original design but it's not normal.

I think it would be better to set your target at 1/2 if you end up at 7/16th that's fine, any lower then that, not so good. Otherwise you could probably disregard anything I said before and build without a neck angle and achieve that height. BUt I don't think it's a good idea.
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  #43  
Old 08-11-2017, 02:49 PM
CabinetMan CabinetMan is offline
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Redir,

I think that this plan is a model of a vintage Martin. Supposedly has forward shifted bracing. Its from Georgia Luthier Supply. It's their Dreadnought SS plan.
I think I will take your advice and shoot for the 1/2" mark.

Thanks again for all the advice, I do appreciate it
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  #44  
Old 08-11-2017, 04:08 PM
dekutree64 dekutree64 is offline
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Well I'll be a monkey's uncle! That is actually a fair design choice for guitars using extra light bracing, but it certainly is uncommon.

I wish I knew more about the history of that plan. Was it drawn from a particular guitar, or is it copied from the source material that many guitars were built from? Because if it was made from a particular old guitar, it's possible that the strings were originally higher, and it had warped over time until there was almost no saddle left, and then someone shaved the bridge thinner instead of doing a neck reset like they should have.

According to my grand theory of guitar design, the string height should be proportional to the soundbox size. Low strings for small guitars to reduce torque on the soundboard so you can lighten up the bracing and lower the resonant frequencies. High strings on large guitars because they can do with a bit stiffer bracing to raise the resonant frequencies, and then the soundboard can support more torque to get more brightness that way as well.

So such low height on a dreadnought goes against my philosophy. If I knew it was the original designer's intent and not just an artifact of an inexperienced plan-maker, then I'd say stick to the plan. But since it's unknown, I'll join redir in recommending that you change it to 1/2" string height.

You are doing X bracing, right? That looks like maybe a ladder brace in front of the bridge on the plan, and in that case I would recommend the lower string height, because ladder bracing relies much more on the stiffness of the soundboard itself rather than the braces, and large guitars need the soundboard as thin as possible to keep the mass down, which of course lowers the stiffness along with it.
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  #45  
Old 08-11-2017, 04:33 PM
CabinetMan CabinetMan is offline
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Duktree64,
Yes, it is x braced.
Hope I'm allowed to do this on here. Here is a ink to the plans that I got.

http://ultimate-guitar-online.ultima...roducts_id=359
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