Ash's acoustic rabbit hole

[ADFinlayson]

Another thing I forgot to mention. I wanted to glue it upside down again but I didn't want to press the gobars in the soft spruce, even with my cork clamping cauls, I suspect it would probably dent it so so I was cleaning up the glue thoroughly once it was clamped one really nice thing about the gobar deck is you can clean up the sides easily without a 100 clamps in the way!

[Andyjr1515]

Well - there's an adage that 'if it looks right, then it probably is right.'  And those top braces look nicely carved.

I was interested in your approach in a couple of areas (consider them stolen  ) which is different to how most builders go about it and there are a couple of things I would have done differently, though none are likely to make a huge difference.

In no particular order:

• Yes - I'm not much further to where you are with tap tuning.  I know what it does, I know what I'm listening for, I can hear it when I get it right, but I'm darned if I know exactly which part of which strut is going to get me the missing harmonic!
• Don't worry too much about the stiffness.  I've just given my dreadnought a mighty push and it is very stiff...and that is balanced, has great projection and a bass tone to die for (pure luck, I promise you)
• That said, the only top braces that I would normally lock into the lining are the X-braces and front cross brace.  The two long offshoots in the main bout would normally thin to nothing before they reach the linings, maximising the flex of the top.  But there are so many other things that will affect the top vibration, I don't think that is over-critical
• I was intrigued that you actually cut through the sides on those braces you lock in.  I generally just cut the linings - which is a pain because it is difficult to get all those joins spot on.  And then I had a think about it.  Assuming that the binding is going to be deeper than the strut ends, this will be routed away anyway.  I may well steal use this approach on my next acoustic
• I generally use spool clamps to fix the top and back - but that's more that my go bar bars aren't really strong enough for that job.  Again, this might be stolen
• Personally, I don't add stiffeners to the sides, although they can't do any harm.  The sides are only there to keep the back and top apart
• 'Wiggle room' for the neck bolt holes - absolutely!  On a couple of my builds, I have more like 'room to swing a cat clearance' 

 

Neck angle!  Yes - critical to get this right and, as I'm sure you know, you cant do it by just measuring it.  You basically need the bridge on - or at least in place - and work off the actual geometry of your specific guitar and height of your actual bridge.  The ObrienGuitars 'Luthier Tips du Jour' is a great source of info for such matters  

Great build!

[Bizman62]

2 hours ago, Andyjr1515 said:

I was intrigued that you actually cut through the sides on those braces you lock in.

Thanks for verifying! I've never built an acoustic but the hundred videos I've seen on the subject made me wonder - and as you said they will be routed away for the binding.

Same with the go bars instead of spool clamps. If they work, they're good! Plus that using go bars allows for leaving the top or bottom oversize which can be of big help in getting the edge just right.

[ADFinlayson]

7 hours ago, Andyjr1515 said:

Well - there's an adage that 'if it looks right, then it probably is right.'  And those top braces look nicely carved.

I was interested in your approach in a couple of areas (consider them stolen  ) which is different to how most builders go about it and there are a couple of things I would have done differently, though none are likely to make a huge difference.

In no particular order:

• Yes - I'm not much further to where you are with tap tuning.  I know what it does, I know what I'm listening for, I can hear it when I get it right, but I'm darned if I know exactly which part of which strut is going to get me the missing harmonic!
• Don't worry too much about the stiffness.  I've just given my dreadnought a mighty push and it is very stiff...and that is balanced, has great projection and a bass tone to die for (pure luck, I promise you)
• That said, the only top braces that I would normally lock into the lining are the X-braces and front cross brace.  The two long offshoots in the main bout would normally thin to nothing before they reach the linings, maximising the flex of the top.  But there are so many other things that will affect the top vibration, I don't think that is over-critical
• I was intrigued that you actually cut through the sides on those braces you lock in.  I generally just cut the linings - which is a pain because it is difficult to get all those joins spot on.  And then I had a think about it.  Assuming that the binding is going to be deeper than the strut ends, this will be routed away anyway.  I may well steal use this approach on my next acoustic
• I generally use spool clamps to fix the top and back - but that's more that my go bar bars aren't really strong enough for that job.  Again, this might be stolen
• Personally, I don't add stiffeners to the sides, although they can't do any harm.  The sides are only there to keep the back and top apart
• 'Wiggle room' for the neck bolt holes - absolutely!  On a couple of my builds, I have more like 'room to swing a cat clearance' 

 

Neck angle!  Yes - critical to get this right and, as I'm sure you know, you cant do it by just measuring it.  You basically need the bridge on - or at least in place - and work off the actual geometry of your specific guitar and height of your actual bridge.  The ObrienGuitars 'Luthier Tips du Jour' is a great source of info for such matters  

Great build!

I understand what you're saying re neck angle and bridge height, from my calculations and meddling, I currently have 11.5mm clearance at the bridge saddle calculation, but I issues on the X to sort out before I get to Y. I think the next few pictures are worth 1000 swear words... Any ideas how to correct this? Essentially the reason the sides didn't go back into the mould comfortably (I now know) is because they became slightly offset, the bottom half is further ahead of the top half.

[ScottR]

I've never built one of these, so this suggestion may be crap.... but I'd be tempted to finesse the mating end of the neck blank to allow it to sit flush while keeping the centerlines  in line. Once your fretboard is in place, it will be invisible.

SR

[Bizman62]

I'm as experienced as @ScottR in building acoustics but I can't help thinking about the reasons why a tenon joint is so common in acoustic guitars - and Les Pauls for that matter. The shoulders can be fitted seamless no matter how slanted the actual joint is. I can see no reason why the same principle couldn't be applied to a bolt-on neck. Just align the centerlines and reshape where it can be done with least effort.

If my thinking is way off, please chime in before something irreparable has been done!

[ADFinlayson]

9 minutes ago, ScottR said:

I've never built one of these, so this suggestion may be crap.... but I'd be tempted to finesse the mating end of the neck blank to allow it to sit flush while keeping the centerlines  in line. Once your fretboard is in place, it will be invisible.

SR

That isn't far off what I've been thinking Scott, I might try taking a bit off the body (not much because the sides are 2.2mm) and a bit off the tenon to reduce the amount I need to take off both parts. I'm hoping that when the bolts arrive, I'll be able to at least bolt it on straight and then scribe then tenon to give me the right shape. If it doesn't bolt on straight then I'm shit out of luck.

I've learnt a couple of things the hard way regarding ordering of tasks on this kind of build. 

1. I won't rout truss rod, shape headstock or stick headstock veneers on prior to getting the neck set right
2. I'll pre drill the holes for the bolts in the heel block prior to gluing in the block so I can be sure the holes are plumb with the block

Fortunately I didn't rush in to routing binding channels. 

[ADFinlayson]

9 minutes ago, Bizman62 said:

I'm as experienced as @ScottR in building acoustics but I can't help thinking about the reasons why a tenon joint is so common in acoustic guitars - and Les Pauls for that matter. The shoulders can be fitted seamless no matter how slanted the actual joint is. I can see no reason why the same principle couldn't be applied to a bolt-on neck. Just align the centerlines and reshape where it can be done with least effort.

If my thinking is way off, please chime in before something irreparable has been done!

If I had gone with a mortise and tenon joint (which I was really close to doing), the mortice route would have been square with the front of the guitar and not square with the centre line and I don't think I would be able to correct the x axis. I think there is a way back from this with the butt joint providing my bolts will allow it to go on square, but they may not.

[ScottR]

1 hour ago, ADFinlayson said:

I might try taking a bit off the body

Actually since there is a block inside the body at that point, you could cut away the side material and join the neck directly to the block. Your fit and trimming of the sides would have to be precise--it would be like inlaying the neck joint into the sides there.

Sounds like a lot more work to me.....

SR

[ADFinlayson]

7 hours ago, ScottR said:

Actually since there is a block inside the body at that point, you could cut away the side material and join the neck directly to the block. Your fit and trimming of the sides would have to be precise--it would be like inlaying the neck joint into the sides there.

Sounds like a lot more work to me.....

SR

That is a cool idea, I'd have to shim a router or something to get the taper right or I'd just be repeating the same angle. although I suppose if it's inset, it doesn't actually need to be that tidy as long as the shape is bang on what the neck heel is. I'll see how I get on with my bolts first and if I can get it to line up

 

[ADFinlayson]

Modest progress tonight, I drilled the holes for my inserts into the heel, using the square to make sure my holes are plum with the 2º off 90 that the heel is cut to. Notice the arrow on the masking tape (exaggerated)... I poked a drill bit of the exact size through the holes in the heel block and could see that the holes were indeed on the piss by a small amount because of the heel block being offset slightly. But drilled those holes plumb on the drill press from the outside in, so they start on centre of the body, so I drilled plumb along the Y axis on the heel but I leant the drill over a hear to attempt to follow on. That will either turn out to be a miracle of magic or utter failure.

My inserts are 20mm m8 steel threaded but I drilled my holes to 25mm depth because I wanted to recess them, I then routed a 2.5mm channel inside the the above pencil line and squared off with the same chisel I skirmished with last weekend, it did a much better job on me than it did on this end grain mahogany, thats for sure. Anyway the idea around recessing the inserts and leaving some clearance is that I can do a bit of sanding while the neck is bolted all the way down to try and correct the issue. I'm hoping shaping the neck heel will reduce the amount of sanding I need to do with all that extra wood removed because I don't know how well that method will work with threaded bolts 

I've shaped my fretboard because I need to start thinking about the other neck angle! This is a dirt cheap fretboard from Maderas something like £2.50 because at this point I don't want to invest any of my nice Indian into this build, in fact that dark spot in the middle is a knot with some small craters that will be filled with ebony dust and glue when it's radiused.

So figuring out my neck angle. My fretboard is currently 7.4mm high which is around what would shoot for (6mm thickness in the centre after radius and small fretwire), clamped very slightly so it doesn't lift the soundboard, just enough to stop it spinning off. The bridge blank is currently 13.5mm thick which is around what I would be shooting for once it's all shaped and the saddle is in place.

and the clearance looks bob on (that's british for good). I did also try this with the fretboard clamped to the neck and holding it butted up to the body to confirm but that was too much of a pain to photograph while I'm still cack handed. If you look closely there is a tiny gap right at the end of the board by the rosette, that could be that the underside of the fretboard isn't perfectly flat yet. If that isn't the case then I think I can correct that by sanding the top and neck in situ with a levelling beam.

At least one thing as gone right.

One last thing, you may notice the top has an outline now - I read in a couple of places that wiping a bit of teak oil (because it penetrates) protects the edge and helped to prevent tearout while routing binding channels. I don't have any teak oil but I do have some Crimson penetrating oil so I thought I'd give that a go. I might just give this one a coat or 2 of oil for a finish anyway. 

[Bizman62]

7 hours ago, ADFinlayson said:

the idea around recessing the inserts and leaving some clearance is that I can do a bit of sanding while the neck is bolted all the way down to try and correct the issue.

Not only that, the recess also is a cup which adds tension to the edges of the neck end which helps in getting any gaps closed. You could even bevel the edges of the neck end towards the recess but I'd leave that until you've got the angle right.

[ADFinlayson]

bolts arrived this afternoon so I made some "progress" this evening amazingly my dodgy drilling actually worked and the neck goes on fairly straight after a bit of fettling. I sanded the body sides at the heel joint with sand paper on a marble plate I have with 80 grit, carfeully pushing forward hold it so the centre line was as vertical as I could make it to flatten the area out a bit. I also did a bit of selective sanding on the neck heel. After doing all that, running the rule up the body centre line and neck at the headstock the rule was just under 2mm off centre and I think thanks as close as I can get it. 

I also did some rough carving of the neck heel, less material = smaller flat surface required and less sanding.

The joint is not perfect, but I think it's as good as I'm going to get it. I've already thicknessed the sides for attempt #2  I'm sure I could trim down the heel some more to but the only obvious looking gap is near where it meets the fretboard and I cant make that area much thinner.

The Mrs popped in and I asked her opinion on the heel veneer. Her options were walnut to match the back or ebony to match the headstock veneers, she chose ebony. So I trimmed the heel down a bit so it sits just under the back stuck some ebony on with a generous helping of superglue. I've got some ebony bing strips to go on and they should meet that veneer nicely. So that's the next job, binding.. shiiiiit

[Andyjr1515]

I'm away from my desktop photos at the moment so I can't show you what I mean, but one thing you can do at the heel is carve a relief between the bolt insert area and the edges....it's only the edges that actually need to seal against the guitar body.  Makes for a lot less sanding and flossing.

[Andyjr1515]

There's a photo of what I mean just down from the top of the page 2 here:

 

[Bizman62]

29 minutes ago, Andyjr1515 said:

it's only the edges that actually need to seal against the guitar body.

You said it better than I did.

[ADFinlayson]

8 hours ago, Andyjr1515 said:

I'm away from my desktop photos at the moment so I can't show you what I mean, but one thing you can do at the heel is carve a relief between the bolt insert area and the edges....it's only the edges that actually need to seal against the guitar body.  Makes for a lot less sanding and flossing.

Thanks Andy, I watched one of those Tips du jour videos you mentioned last night and he did just that. Seems I had the right Idea routing a bit of a chamber around the bolt area just didn't go as far as I could. Another thing I've learnt for the next one here, do that but also shape the heel prior to attempting to fit the thing!

[ADFinlayson]

Made a start on binding this evening. After exhaustive research on how to do it, every video I watched involved a fancy binding jig that kept the body square and/or a binding trimmer jig where the router slide sup and down for perfectly square binding, or painstakingly by hand with a purfling cutter. I have none of these tools or jigs nor the patience, so I went at it with the Makita trimmer, I just carefully routed with a 2mm rebate bit from Radian tools. 

I don't know if it was down to the good quality bit, the careful climb cutting or the pre oiled wood, but the channels came out pretty much flawless   I had a bit of fluff on the back, surprisingly more so than on the spruce

so I carefully pulled back in from the edge with 220 on a block and that tidied it all up nicely.

I routed the channels as deep as I could, just a hair under the binding height because I was a bit hap hazard with the height the transverse brace, just about managed to hide it

Then I fired the bender up and had a go at bending some ebony. The strips from Stewmac weren't much longer than what I needed so I need to get the waist bend (first bend) in the right spot, so I stick a bit of masking tape round the channel and marked where he bends were, arrow direction denoting which way the bend needed to go. Then transferred the marks on to the binding strip.

The first strip started off really well, the waste went in perfectly bending at 225ºC and spraying the strip with water, I thought I had this nailed then it snapped on the next bend   so I superglued it back together for later, let the other 3 soak in the bath for 20 mins and jacked the iron up to 280º. The second one went fine, I broke the 3rd one so reused the first broken one which went fine then the next one went fine too. 

The taping up however did not go very well. I had them bent pretty close to the shape but struggled to get them to conform perfectly and the ebony is so damn hard that the tartan tape didn't want to hold it. I was thinking about using some garden twill to tie it on but I'd already routed both channels and didn't want to damage the other. So I just superglued it all on. Used some accelerator and medium thickness superglue to tack it on in places, then taped it up and wicked in a load of fine superglue.

I don't know what the longevity of superglue will be like, but it certainly seems to have worked quite well, apart from the mess. I've got a few hairline gaps, but the beuty of ebony being that I can use the ol' dust and superglue trick.

Got one more piece to get on there tomorrow, then I'll start scraping it all back. Starting to look like a real life acoustic!

[Andyjr1515]

Lovely job with the binding

[ADFinlayson]

3 hours ago, Andyjr1515 said:

Lovely job with the binding

I wouldn't go that far   but it's on, I'll check at lunch time and see if it's actually still on there. I reread your limba dreadnaught build thread last night. If I'd have remembered your comments about binding, ebony and richlite, I will have made different material choices because it was a PITA to bend compared to other woods and horrible to true to glue up. I'm quite tempted to get make myself a LMI style bending jig with heat blanked for the next one. Certainly not buying one, not at nearly £500!

[Andyjr1515]

3 hours ago, ADFinlayson said:

If I'd have remembered your comments about binding, ebony and richlite, I will have made different material choices because it was a PITA to bend compared to other woods and horrible to true to glue up.

Yes.  The surprising thing is that Tonetech (for  non UK, these are one of the major suppliers of these kinds of things in the UK) have moved 100% to Rocklite (Ebanol and Sundari) for binding and it is majorly flawed for this job because of the short fibres.

I think that now I know it's not just me, I might contact Rocklite to let them know it's an issue for hand benders.  I still own and am happy with the 'first in the world all-Rocklite guitar' so hopefully they'll know it's a friendly comment and not just a bemoaner one...

 

[ScottR]

12 hours ago, ADFinlayson said:

Starting to look like a real life acoustic!

Indeed it is.

SR

[ADFinlayson]

Funny story, I was bending the last bit of ebony binding on Friday night (my last piece of binding) and it broke in 3 places, bollocks.

So I ordered some more but it's going to be a 10 days at least before it arrives. Seeing as the mold was now free. I thought I'd strike while the iron was hot (pun intended) and practice bending some more sides. One thing led to another and I seem to have another OM build under way.

Black limba back and sides this time, another German spruce top, again cheap stuff from Maderas Barber, and I have a sizable offcut from the neckthrough bass of last year that would serve for back and sides braces and the heel and end blocks.

So I bent the sides, first one took well over an hour to get right and I was about to throw the towel in then it all just kind of smooshed into shape, second one took about 20 minutes and was much easier, probably because it had been soaking in the bath the entire time I was warring with the other one.

Overall, much better result than the walnut, I had to cut these down to 13cm wide in order to fit them on the bending iron, but unlike last time, I didn't cut the taper, I kept them square which made it A LOT easier to bend them square. It was still hard work though, I've decided I don't like bending wood much.

I cut them to length, put the whole thing in the vice and used their shape to sand the end block that I had just cut out of the limba offcut before glueing those in. Something I didn't do last time was pay any attention to grain direction. After a bit of research I opted to have the grain oriented so end grain was coming out of the side, so the sides are glued to face grain, the top and back and glued to side grain and the end grain is glued to nothing, I expect the reduces strength with bolting through them, but improves strength on the top and back.

These are my blocks/braces - forgot to photograph the heel block, but I shaped it and drilled the bolt holes along the centreline prior to gluing up and made sure it was bang on centre with the mold on front and back, something I'm not convinced I did well on the walnut build, which could explain some of my later problems. The thin strips are my back braces, 15mm x 7mm, middle is the end block, and the piece on the left will be cut up to make 3mm side braces.

I didn't much like the figure pattern on the back set, so I moved the joint around a bit. Made it more awkward to glue up but I like it.

I moved some tools around and now have a copy of the plan on the wall, much easier to see those dimensions!

Then I got all the back braces on, slightly different method this time - I cut the back into a wedge before glue up so I only had pieces of offcuts, I glued in the back braces first, then cut the perpendicular braces to their length and filled in the gaps

With that lot drying, I got to dimensioning the sides. Borrowing @Andyjr1515's method, I put the mold top side down and slipped my side profile template in and scored round it with a pencil line. You can see I've got a bit of a scorch mark at the waste, I'm hoping that will scrape out without losing too much material. That was the first bend and the iron was too hot from where I'd been breaking ebony. I went from 290ºC down to about 250 and had much better results with the limba.

Then I went at it with a chisel followed by a block plane. Quite satisfying!

Glam shot

I tried to remain just a hair above the line and blocks to account for the radius sanding

Then I got to work on glueing in the kerfed lining. This is the back, one side glued and second side a dry run.

It was at this point I realised I must have lost a kerfing strip and was one short, bollocks.

So rather than wait a couple of weeks for some more and risk it looking different to the stuff I bought 18 months ago. I came up with a "work around". I've followed Driftwood Guitars method for cutting the bevel, drew the profile I wanted, notched it out close to depth on the spindle sander, but blind so had to check progress frequently. 

Then very carefully chiselled downhill from both sides until it looked right.

This was a PITA to get right, I put the offcut under the side, drew round it, bandsawed as close to the line as I could then finessed on the spindle sander, this took a lot of back and forth checking the fit. It's not perfect but it's not bad, good enough!

And now it's glued in. I don't know how this is going to go,  I may well have bitten off more than I can chew  luckily it's all cheap woods and offcuts

I don't know what to do about binding material for this one. My taste tells me that nothing goes better with limba than ebony, but ebony is such a nightmare to bend. Flamed maple could be cool, but if the joints aren't much to much, there is no hiding it with dust and glue like ebony. Any suggestions? 

[Andyjr1515]

Wow!

 

On so many levels...

[ADFinlayson]

2 hours ago, Andyjr1515 said:

Wow!

 

On so many levels...

Thanks Andy, I was chuffed with my output for a weekend, I didn't even get out there until gone midday on sat and I made a chilli and watched 2 Disney films with my 3 year old today. I think some of this stuff could go quicker though. I'm pretty much sold on making a side bending machine and I could do with making one of those LMI style plate joining jigs so I don't have to MacGyver something on the workmate or the floor every time I do a glue up. This was this evenings glue up of the top.

And here's the arm bevel out of the clamps. Came out pretty good, just that spot right by the heel block it isn't perfect, but no worse than some of my kerfing. Speaking of which, that's something I could do with getting better at. I always manage to break it right at the waist and that's the one spot that it can be seen from the sound hole. 

Need to have a scrape around under the bevel to clean up and see if I can reduce some mass before I glue the vertical braces in.