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Martin Guitar Kit (It's First Public Outing!)

This is where we don't want anything but evidence of your finest wood butchering in all its glorious, and photograph laden glory. Bring your finished products or WIP's, we love them all, so long as there's pictures, and plenty of 'em!

Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 11 Jun 2020, 09:56

There's not a lot for me to post for a while, because I have to 'voice the soundboard'. This entails profiling and scalloping the braces and listening the the note from soundboard as you tap it! Well, I won't know what I'm listening for.

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This voicing, from what I've researched appears to be a bit of a dark art. But, scientifically, the more mass that is removed from the braces, the weaker the soundboard becomes, but that can have advantages in the sound that comes from the sound hole when the strings are played.

As this model is going to be a 12 String, with something like 60% more force applied to the bridge than a 6 string, I'm not going to do anything to risk damaging the soundboard once it's set up and playing. But, it is the height of the braces, rather than the width of them that provides their strength, so I shall do some profiling to a tall triangular shape, and only just scallop the brace ends to nothing on the outside of the soundboard.

Halfway though the brace gluing, I did pick it up and gave it a few taps. The note sounded musical to my ear, but what I did notice was that the vibration from the tap sustained for a couple seconds. I took heart from that.

Watch this space.
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 11 Jun 2020, 18:58

I got a bit of carving done today. Good job the chisel was sharp.

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Never done any of that sort of curved carving before.

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The X braces and top bar were carved down to about 2mm by using 2mm spacers either side of the brace.

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The tone bars etc were all carved down flush.
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 12 Jun 2020, 18:31

A day and a half (well my type of day and half at 2 to 3 hours a day! :D ) sanding and scraping. Taking the trouble to remove every piece of dried glue and to sand the profiles triangular rounded while maintaining their height.

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I hope you can tell the difference from the previous photo, because the sanding has done the arthritis in my shoulder no good at all, and I'm going to need a day off. No idea what I'll do with myself.

I've been holding it at a node point and knocked the board the board with my knuckle. It still sounds musical and I can still feel the sustain.
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby fiveeyes » 13 Jun 2020, 00:07

Malc...when you challenge yourself, you go all in, eh?
:text-coolphotos: :text-bravo:
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 13 Jun 2020, 10:31

fiveeyes wrote:Malc...when you challenge yourself, you go all in, eh?
:text-coolphotos: :text-bravo:
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Thanks, 5E. It is a challenge, but I think I might find a piece of fine furniture more of a challenge.
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 13 Jun 2020, 10:32

Hopefully, this video might explain a bit better what the bracing system does.

[youtube]HQ9WosApXvA[/youtube]
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Andyp » 13 Jun 2020, 11:17

Interesting Malc, I had no idea. I wonder if I could hear the difference.
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 13 Jun 2020, 11:54

Andyp wrote:Interesting Malc, I had no idea. I wonder if I could hear the difference.



Probably only if the wrong one was used in the wrong environment.

A strummed guitar in a band or group setting through the song would probably not be scalloped to maintain the strength and volume required.

A solo performance of just singer guitarist, would probably be a scalloped version to add the tone and clarity to the sound.
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 13 Jun 2020, 22:36

I'm not sure I've finished the inside of the soundboard yet. I might have to do a little more research. As this will be a 12 String with and addition 100lb of force on the bridge, I might add a third tone bar, and scallop the three of them.

But in any case, the crossed halving joint was poorly cut and was not a tight fit, so the usual remedy for that after installation is to cover the 'cross' with glued muslin. More reinforcement to absorb/reflect the forces applied by strings plucked.

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With the braces all sanded and scraped it was time to fit them in order to notch the kerfed lining of the rim. I'm afraid I didn't get any images of that part of the process, because I was too impatient try see if it would fit. It only needed a little bit of fettling, and then.......

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....it fitted!

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And with another bit of fettling...

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....so did the back!

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I was quite chuffed with that.

I looked at the back braces and realised I hadn't shaped their profiles like the front one, so I set to and scraped and sanded them. I've order a lump of spruce form a luthier supplier and will make a 5th brace for the back at the top, where the original should have gone but was not long enough to span from lining to lining.

So, I am in the hands of the courier services. Till then.....
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 14 Jun 2020, 15:52

While waiting for the courier, I thought a little housekeeping should pass the time. As I'm getting close to the time when I glue the top and then the back to the rim, I thought I'd raise the go-bar deck. :)

Did you see what I did there? Oh, please yerselves!

Fortunately, Screwfix do a little pack of 5 x 300mm M8 studs which perfectly fitted the existing M8 tapped holes in the stanchions (for want of a better word). I've raised the upper deck by the current height of the rim plus top and back, so will use the same go-bars to clamp first the top and then the back when I'm satisfied there is nothing more I can do to them.

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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 14 Jun 2020, 17:49

Having raised the go-bar deck, I had to adjust the for and aft heights to accommodate the different heights of the rim.

Once I got there or thereabouts, I thought what the heck, why not try a dry run! So I put the rim in the mould in, then placed the top on the rim, and adjusted the deck accurately. I then covered it with its soft mat and started clamping with go-bars.

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It fitted all the way round with no gluing gap. Chuffed!
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Pinch » 15 Jun 2020, 19:56

Looking superb Malc!

I didn't realise there was so much involved. Proper job Sir. 8-)
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 15 Jun 2020, 21:06

Pinch wrote:Looking superb Malc!

I didn't realise there was so much involved. Proper job Sir. 8-)


Cheers, Paul. Neither did I till I tried my first one. This is my second, and if something comes off, which I can't share yet, I may have third to start in a month or so's time.
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Re: Martin Guitar Kit (Voicing the Soundboard)

Postby Malc2098 » 17 Jun 2020, 21:34

I've watched hours of videos of voicing techniques and the science behind them and my eyes are having out like Foden push starts!

I sort of get it, I'm told that you need to balance the stiffness across the guitar top with with the stiffness along the top. I'm told the things that control the stiffness along the grain and the things that control the stiffness across the grain.

I've gone through the 5 steps

  1. Flex the top to evaluate stiffness and weight.
  2. Tap to evaluate frequency distribution.
  3. Shape the braces in small increments at a time
  4. Re-evaluate the first two points
  5. Repeat as required until the frequency distribution is optimised at the desired stiffness

Well, I've flexed, I've tapped, I've listened, I've even recorded the taps, I've evaluated and evaluated and repeated, and .....well, I don't know. I just don't have the experience. This is the start of my experience.

I tell you what, I noticed at one point how the taps sounded musical, I tidied up the shaping, tapped again and it wasn't musical any more! Grrr!

I'm not going to shave any more off! This photo shows how much I've shaved and sanded, compared to previous photos and that's going to be it. It is quite stiff along the grain, but I can feel that it's not so stiff across the grain which is achieved by shaping those little finger side braces.

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A lovely lump of quarter sawn spruce arrived today so now I can make a brace for the back and install it and remove the one that was too short. Then I can get on to glue the top and back to the rim.
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Re: Martin Guitar Kit (Tap Tones)

Postby Malc2098 » 19 Jun 2020, 19:02

Wow! I've just learned how to upload to YT!

So here goes! This is what tone tapping is as you profile the braces while voicing the soundboard.

[youtube]qiEGTX5hNRc[/youtube]
Last edited by Malc2098 on 19 Jun 2020, 21:47, edited 1 time in total.
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Re: Martin Guitar Kit (Revisiting Back Bracing)

Postby Malc2098 » 19 Jun 2020, 19:52

I've finished trying to 'tune' the soundboard. So, I started making a new brace for the back where it should have been and removing the old one.

That lump of quarter sawn spruce is nice, but it's just off the quarter, so I bandsawed a length 90 degrees to the rings and fashioned a brace. I scribed the curve of the back onto it and sanded it to the curve. I then cut a housing in the centre graft to accommodate it.

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I then started planing away the wrong brace.

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When it got low, it was time for a chisel and the router plane.

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Then with a scraper and some sandpaper, I even got the glue.

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Dry fit to check the curve.

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And on to gluing it.

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Re: Martin Guitar Kit (Setting the Go-Bar Deck)

Postby Malc2098 » 21 Jun 2020, 20:14

This must have been about the eight time I had a dry run at setting the go-bar deck before I glued the top to the rim for real. I'd gone round so many times making sure that there were no gaps in the glue line, even using feeler gauges to check. After this video, I glued it for real and won't check it till tomorrow! Ooo err!

[youtube]6o9GNJpIBI0[/youtube]
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Re: Martin Guitar Kit (Removing the go-bar clamping)

Postby Malc2098 » 22 Jun 2020, 15:11

Here's the result!

[youtube]vGLQbijMERY[/youtube]
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Re: Martin Guitar Kit (Setting the Go-Bar Deck)

Postby DaveL » 22 Jun 2020, 15:26

That looks good, no gaps then?

Progress towards a finished instrument is good.
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Re: Martin Guitar Kit (Setting the Go-Bar Deck)

Postby Malc2098 » 22 Jun 2020, 15:41

DaveL wrote:That looks good, no gaps then?

Progress towards a finished instrument is good.



Weeeell....I've gone round again with the feeler gauge and there's one or two spots where it just starts to go in, but.......the binding and purfling rebates will go beyond them, and I hope into glued joint.

The housings where the braces fit in the kerfings aren't good, so I will fill them with glue filled with sawdust.

I routed the overhang off this morning (video to follow). That was nerve-racking! This afternoon, I will go round the inside and clean up the glue squeeze out and see if there are any other gaps that need filling.
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Re: Martin Guitar Kit (Routing the Top Overhang)

Postby Malc2098 » 23 Jun 2020, 10:26

Bloomin' nerve-racking!

[youtube]mOgQrGsaJ7E[/youtube]
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Re: Martin Guitar Kit (Routing the Top Overhang)

Postby Robert » 23 Jun 2020, 11:35

Three things come to mind..

I'd never try cutting that much off with a trim cutter but you obviously got away with it.

Step away from the 'speed up the video' button ;)

Keep the posts coming as watching and learning the intricacies is good. Thanks.
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Re: Martin Guitar Kit (Routing the Top Overhang)

Postby 9fingers » 23 Jun 2020, 12:06

Robert wrote:

I'd never try cutting that much off with a trim cutter but you obviously got away with it.

.


+1 brave man!
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Re: Martin Guitar Kit (Routing the Top Overhang)

Postby Andyp » 23 Jun 2020, 12:51

with apologies to Kipling

you're a braver man than I..


But then he probably made exceedingly good guitars. :) :)
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Re: Martin Guitar Kit (Routing the Top Overhang)

Postby Malc2098 » 23 Jun 2020, 12:53

Robert wrote:Three things come to mind..

I'd never try cutting that much off with a trim cutter but you obviously got away with it.

Step away from the 'speed up the video' button ;)

Keep the posts coming as watching and learning the intricacies is good. Thanks.



Thanks, Robert and Bob.

In answer, (or my defence) I'd say the overhang was just less than 1/8" thick and I slowed the router speed down to half as the cutter was 19mm diameter.

I'm not speeding it up, I'm filming in time lapse mode, because I am posting this WIP on different platforms and some set a time limit and some set a file size limit. I started the YT channel because I only have to upload it once and then give each platform the link, which manages my up/download allowance. I apologise if the speed/frame rate is annoying. I am always happy to answer questions after posting.

I've just played it back in YT setting the playback speed to .25 which places it closer to real time and gives the viewer time to absorb what's going on a bit better, but the viewer has to set their own playback speed.

I think some of these processes are too long and possibly boring for some viewers in real time and so I set the camera to time lapse and go a slow as I can, which is good anyway, except when gluing, and hope the time lapse captures most of the details.

Thank you for your forbearance.
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