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Martin Guitar Kit (Purfling begins!)

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 (Routing the Top Overhang)

Postby Malc2098 » 23 Jun 2020, 12:53

Andyp wrote:with apologies to Kipling

you're a braver man than I..


But then he probably made exceedingly good guitars. :) :)



Tres drôle! :D
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Re: Martin Guitar Kit (Closing the Box)

Postby Malc2098 » 24 Jun 2020, 12:10

Out come the go bars again and I fitted the back to rim, 'closing the box'.

There was one section close to the bass side waist that the gap needed much encouragement to close! That's why all 60 go-bars were used.

It was so warm yesterday that I had to slow the gluing process down somehow. I painted water onto all the gluing surface of the kerfed linings. Then I went round with the mini glubot and trailed a line round the whole lot and smoothed with the my finger. I wiped up any dribbles down the inside which occurred at the brace housings.

I then went round again with the glubot leaving a line of glue around the whole rim and some more on the neck and tail blocks, and then clamped the back down.

IMG_4012.JPG
(392.32 KiB)


You might notice that I made a tapered dovetail blank to fit in and protect the tapered dovetail housing in the neck block.

This morning I removed the go-bars.

IMG_4015.JPG
(250.57 KiB)


I then whizzed round with the bearing guided cutter, at half speed again.

IMG_4027.JPG
(397.09 KiB)


That area of the waist that needed encouragement to close?! I managed to find a gap about 10mm long and could get a .003" feeler in about 3mm which suggests to me that the kerf lining was glued to the back at this point. The feeler would not go all the way through. So, when I rout the rebates for the binding and the purflings, the kerf join will still be sound.

I taped my phone to a stick to try and video the inside of the box and look for any defects, but they're taking an age to upload.

EDIT
Yer Tiz. Must sack the cameraman and get a better one!

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Re: Martin Guitar Kit (Closing the Box)

Postby Malc2098 » 25 Jun 2020, 12:55

I've trimmed both the top and back to the edge of the rim. I've sanded the sides level with the top and back edges in preparation for the binding and purfling rebates, so that the follower bearing has a smooth path.

Now I get to look closely at the glue lines to see where I need to improve with any future builds.


Well.......not perfect, but not bad for an amateur, I'd say.

And here's the go-bar deck and mould broken down to be packed away for the next build. :)

IMG_4039.JPG
(415.25 KiB)
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Re: Martin Guitar Kit (Closing the Box)

Postby TrimTheKing » 25 Jun 2020, 15:08

Loving this mate, thanks for sharing to this level of detail. :eusa-clap:
Cheers
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Re: Martin Guitar Kit (Closing the Box)

Postby MY63 » 25 Jun 2020, 17:44

Nice work Malcolm
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Re: Martin Guitar Kit (Closing the Box)

Postby Malc2098 » 25 Jun 2020, 18:30

Cheers, chaps. Writing the blog helps me sort stuff out in my head as I progress through the build.

Might be a little wait, I'm in the process of designing and building a router tower that maintains the cutter perpendicular to the sides for the binding rebate, because the back and the top are curved across their faces so the router plate cannot rest on them, and has to be supported off the guitar, but touching it so that it follows the contours. I shall be employing bearings, and drawer slides!

It's complicated to explain verbally, well it is for me, but they charge hundreds of squids in the luthier suppliers for them.
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Re: Martin Guitar Kit (Closing the Box)

Postby fiveeyes » 26 Jun 2020, 01:23

Echoing all of the accolades, that have been tossed your way. This is a crackerjack WIP!
Woody stuff, for me, is done only when necessary, in the summertime. Your WIP keeps me 'in sawdust'.
Thank you :text-coolphotos: :text-bravo:
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Re: Martin Guitar Kit (Closing the Box)

Postby MattS » 26 Jun 2020, 08:01

That glue joint looked pretty good to me in that spin round! I'd be so nervous routing that edge!

The WIP is brilliant really enjoying this one.
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Re: Martin Guitar Kit (Closing the Box)

Postby Malc2098 » 26 Jun 2020, 09:40

Gents,

Thank you for your kind words. I am really an amateur. This is only the second acoustic guitar I have made and I haven't even finished the first one yet!! But It plays nice. When this one gets to the same stage as the first, then I'll finish them together.

The main things that I have learned from that spin round video is that the glue line shows different thicknesses suggesting that the faces were not meeting properly, even with all the clamping, and the other is that one or two of the visible joints are about 0.5 to 1.0 mm deeper than the binding, which means they would be visible after binding.

I've yet to resolve that one.
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Re: Martin Guitar Kit (Closing the Box)

Postby Malc2098 » 26 Jun 2020, 18:18

Well, I've made a start with solving the depth of binding issue. I can use the main 6x1mm binding with a 1.7mm purfling for the side which gives me 7.7mm covering the brace joint. Then I've got a tiny 1mm purfling for the top. I could also buy different sized purflings and mix and match to get deeper or wider, but I think I'll stick with what I've got.

I've also made a start with the router tower to accurately rebate the top and back for the binding/purfling. I made a baseplate from pdf for the router which will connect it to a box which can be raised and lowered in a housing, much like a vertical drawer. I've employed the trimmer guide that comes with the router to bear against the sides of the guitar and follow those contours. The guide is adjustable to set the lateral depth of the cut.

I've fitted another bearing (a spare bandsaw guide bearing) 90 degrees to the trimmer bearing so that can follow the contours of the top and back. The vertical depth of the cut is set by adjusting the router body within router base.

IMG_4042.JPG
(252.97 KiB)
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Re: Martin Guitar Kit (Closing the Box)

Postby Andyp » 26 Jun 2020, 20:05

Methinks that is going to be more scary then the trimming you did earlier. Hope it goes well.
cheers

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Re: Martin Guitar Kit (Closing the Box)

Postby Malc2098 » 26 Jun 2020, 20:36

Andyp wrote:Methinks that is going to be more scary then the trimming you did earlier. Hope it goes well.


It's all scary at the moment, Andy. On the first guitar I made, I used my old Trend T with its trimmer guide, and by hand. It was scary, but also uneven. which is why I want to follow this route.

I've got the body wrapped up inside a pillowcase and put back in the box the kit came in, so I don't dent, ding or drop it while I work on this stuff.

I shall try and provide a video of the routing, but there's more of the tower to design yet. :)
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Re: Martin Guitar Kit (Closing the Box)

Postby Malc2098 » 28 Jun 2020, 15:15

I've boxed the router so it should slide up and down the tower. Still haven't got a clue of how to make the tower, but one thing at a time.

IMG_4044.JPG
(311.32 KiB)


I now need to know how high the guitar body will sit on its cradle before I design the tower. So let's make a cradle.

IMG_4046.JPG
(332.19 KiB)


I'm quite chuffed because the ply and mdf comes from all the offcuts from making the mould. :)

And this is what it does. It allows me to maintain the guitar body stable and rotate it to let the router, which is in a fixed position laterally, bear agains the edge and cut the rebate it rotates.


IMG_4047.JPG
(261.74 KiB)


Unfortunately, it also demonstrated that my work in trying to keep the rim in the same plane all around its contour was not successful. If it's 90 degrees to the base at the neck end, it's about a degree out at the other end. and varies all the way round. Hey ho.
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Re: Martin Guitar Kit (The Router Tower)

Postby Malc2098 » 30 Jun 2020, 13:15

With apologies to Heath Robinson, here is the router tower, almost.

IMG_4056.JPG
(387.04 KiB)


The router sits in the 'drawer' shown in the previous post with horizontal and vertical bearings for the workpiece to bear against. The 'drawer' rides up drawer runners and is counterbalanced by a bucket of M10 bolts which are connected by a line that runs over two pulleys made of old castor wheels with grooves turned into them.

IMG_4057.JPG
(349.97 KiB)


I then 'tested' the movement of the router carriage by adding and removing bolts from the bucket until I felt that it was the right control of movement against the workpiece.



After I was satisfied with the test, I screwed the feet into the uprights and screwed a diagonal brace across the back and improved the method of clamping to the tablesaw bench and it feels really rigid now.

Well, I'm going to have to bite the bullet and rout the binding and purfling rebates. I shall be routing to tolerances of 0.1mm, the binding depth is about7.3mm x 0.9 mm wide. The purfling will be about 0.7 wide x about 0.9mm deep. Oo-er!
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Re: Martin Guitar Kit (The Router Tower)

Postby 9fingers » 30 Jun 2020, 15:58

I'm usually the last one to suggest hand tools for a job! :lol:
However, cutting the groove like this I'd be looking at a scratch stock to enable you to take it very slowly and progressively.

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Re: Martin Guitar Kit (The Router Tower)

Postby TrimTheKing » 30 Jun 2020, 16:05

9fingers wrote:I'm usually the last one to suggest hand tools for a job! :lol:
However, cutting the groove like this I'd be looking at a scratch stock to enable you to take it very slowly and progressively.

Bob


He's not cutting a groove, he's taking off the whole top edge.

I love the ingenuity here, but would it not have just been easier to build a sled that slid on legs on the table top, fix the router to the top of the sled with a hole through for a bottom bearing guided bit, extend that down to the depth required then run around the whole body?

Same principle as you've gone for but would have been a heck of a lot less work I would think.
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Re: Martin Guitar Kit (The Router Tower)

Postby Malc2098 » 30 Jun 2020, 16:17

Cheers, Chaps.

Not sure how yours works, Mark. I was only trying to copy the commercial versions. My jig is not using a bearing guided cutter, it's using a trim guide which is attached to the router base, not the router bit. The router has to stay stationary in the horizontal plane, but be able to move vertically, and the workpiece's radii of the guitar's sides' curves need to stay in line with the cutter and the trim guide. That can only be achieved if the guitar body is handled manually, and therefore the router needs to be stationery (in the horizontal plane). I understand it, I think.
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Re: Martin Guitar Kit (The Router Tower)

Postby Robert » 30 Jun 2020, 16:20

I had a quick search to see what other jigs are used for this and they all seem complicated :)

There was a tatty looking one for sale on ebay for a lot of money so I can see why it was worth putting the work in.

I'd suggest making some test cuts on some scrap with nice clean edges to see how consistent it performs. vibration when the router is cutting might show up some movement in those drawer slides. Not sure they are as accurate for guiding as they feel just sliding them back and forth.

Good luck :)
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Re: Martin Guitar Kit (The Router Tower)

Postby Andyp » 30 Jun 2020, 17:56

Robert wrote:Good luck :)


:text-+1:
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Re: Martin Guitar Kit (The Router Tower)

Postby Malc2098 » 01 Jul 2020, 17:57

So, here went the test cuts. I've got no way of micro adjusting the vertical cut, I just have to be careful loosening the motor in th body, moving it and retightening, but there is a micro adjust on the horizontal, comes with the trim guide.

First try single deep rebate.

IMG_4065.JPG
(233.27 KiB)


First try adding the shallow rebate.

IMG_4067.JPG
(217.22 KiB)


Several micro adjusts later on another piece..........

IMG_4069.JPG
(168.82 KiB)


and from a different angle.....

IMG_4070.JPG
(190.53 KiB)


Those are three pieces of plastic; the single white piece is the binding. The black/white/black piece below is a purfling and the black/white piece on the top is a purfling.
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Re: Martin Guitar Kit (The Router Tower)

Postby Andyp » 01 Jul 2020, 18:26

Can you test an undulating cut to mimic the slight rise and fall of the guitar ?
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Re: Martin Guitar Kit (The Router Tower)

Postby Malc2098 » 01 Jul 2020, 19:46

Andyp wrote:Can you test an undulating cut to mimic the slight rise and fall of the guitar ?



That'll be the next trial.

BTW, it's nice downward spiral cutter from Whealdens.
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Re: Martin Guitar Kit (The Router Tower)

Postby Malc2098 » 02 Jul 2020, 22:44

Make yourself about 30 minutes of space, fix yourself up with a glass or two of your favoured lubrication and enjoy this video.

It has a certain resonance with me (see what I did there :) )

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Re: Martin Guitar Kit (The Router Tower)

Postby Malc2098 » 03 Jul 2020, 16:06

I was in the process of videoing the live rout of the first rebate to the back of the guitar, having spent ages getting the adjustment right. The tower is successful for the most part, there are a couple of places near the waist that I cannot get the work right in and will have to manually increase the size of the rebate to match the rest.

I was on the last curve when this happened.

IMG_4081.JPG
(268.96 KiB)


I was doing a climb cut because I didn't want to tear out, but I wasn't holding cradle firm enough and the blighter bit me.

I've got another 1.0mm rebate to go which will reduce the width of the break, but I am open to advice as to how bet fill the defect. I've got loads of leftover mahogany to make dust to get a match and this is the back of the guitar and will not be noticeable in the most part. I am Ok with the repair being visible, but I would prefer it not to be too obvious.

Ideas will be gratefully received.
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Re: Martin Guitar Kit (The Router Tower)

Postby Robert » 03 Jul 2020, 16:52

I often put some varnish on before routing a fragile edge as it stabilises the wood. Wish I'd said so earlier now.

Think I would try planing the damage flat and gluing a piece on with the grain matching rather than mess about with dust. If you have got spare material why not simulate the repair before doing it for real. Clean it up and wipe some finish on to see how it might look.
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