Thinking of building an acoustic ---> It's done!

SteveF

Very inspiring build! 

Misterg

^Thank you!

Misterg

Bridge(s) of sighs.

In order to finally set the neck angle, I needed a bridge:

 Mark I

Mark II

Mark III

I cheated and made the bridges on my small CNC router:

I designed the MKI to be aesthetically pleasing to me - I quite like having the bridge pins in an arc. While I had considered the break angle over the saddle when designing it, it struck me a week later that the strings would need to pass straight through the wood in front of the recessed pins. (D'oh!)

Enter the MKII which was a re-work of the MKI with recess in front of the pins.

I used these ones to set the neck angle which (surprisingly to me) was still too high at the bridge. After chasing my tail somewhat, I realised that taking the guitar from storage at ~50% humidity to the utility room at ~65% humidity or the shed at even higher humidity was causing the top to rise and fall a surprising amount.

I eventually ended up with a gap of ~1.2mm between the bridge and a straightedge over the frets (it's 1.6mm in the photo above) with the guitar in 50% humidity - the book says 0.4 - 1.6mm (1/64" to 1/16"), and I thought I was done.

So: time to accurately position the bridge. Only then did it dawn on me to check where the holes would fall on the bridge plate...

Thus the MKIII!

This has the holes in a straight line, quite close to the saddle. The original Grellier plan does show the bridge pins in a slight arc, but even these come quite close to the edge of the bridge plate. My arc was more pronounced, and I also managed to lose about 2mm from the neck length when adjusting the neck heel (I was really surprised, as I didn't seem to be taking off much material) so I'd ended up with the middle four pins well clear of the bridge plate. (Double D'oh!)

I did get a fit I was pleased with on the neck/heel :

 

There's a very slight gap under the last ~three frets which I'm just going to clamp down when I glue it on - those frets are for ceremonial use only for me.

I had one other minor disaster:

When I was checking the neck angle, the straight-edge picked up that there were a couple of high frets. I put the neck on to bench and tapped them down, no problem. Or so I thought until I tried to refit the neck - the metal insert that the neck bolts thread into had moved out of position when I was tapping the frets down. I had to drill a hole in the bottom of the heel to get it back into position. Luckily this will be hidden by the heel cap (which I still have to make).

After that, I think it's on to finish sanding and finish... 

My current plan is to use Tru-Oil (which I've used previously) on the neck and to try and French Polish the body (which I've never done before!). I've been experimenting on a scrap of rosewood and I think I've gained enough confidence to give it a go - I can always wipe it off again with some meths!

Thanks for reading

Roland

Silent admiration 

fastonebaz

I admired loudly but privately.   Even the thought of creating one bridge to that quality makes me pinch myself awake from a dream 

Misterg

Thank you!

 Even the thought of creating one bridge to that quality makes me pinch myself awake from a dream

I can't take much credit - the CNC does most of the work and produces an almost a finished part - just needs a light sand and it's done.

grappagreen

Still amazing.. brilliant

Misterg

I am still here and slowly making progress. 

 A few little jobs needed to finish off the construction phase... 

Sanding the bottom of the bridge to match the curve of the top:

Then some very careful measuring, checking, and checking again to try and set the bridge in the correct(?) place.

With a double check using string lines

Then it was squeaky bum time as I drilled the top through the outer holes in the bridge:

(^Dramatic reconstruction - I didn't try and take a photo while I was doing it!)

I pressed the clamping caul (that I'd made before closing the box) under the bridge plate while drilling to try and avoid tear-out, and it seemed to work.

Time will tell whether the holes are in the right place.

Making the neck heel cap was one of those jobs that just took much longer than I was expecting. I found it very fiddly to try and get it to fit well against the body, but eventually I was happy, so I fitted the neck and glued the oversized cap on in-situ, followed by carefully removing the neck to stop it being stuck to the body:

Carving it to shape was OK and I was pleased with the eventual fit, but wish that the glue lines weren't quite so obvious.

I also decided to mark and drill a hole for the end pin at this stage (I will still need to ream it out). I pushed the long stick you see in the photo against the tail block as I drilled the hole to discourage tear-out.

I couldn't resist putting it all together to get an idea of how the finished item might look:

Stoked.

fastonebaz

I was getting worried you'd stopped and smashed it with the radio silence then.   But thankfully no,  the books is looking as sharp as ever.  Amazing work.   

Misterg

^Thank you

Some of the slow down in posts is because what's left is mostly fiddly bits and finishing that needs time and patience, but isn't particularly noteworthy. I've also had some other stuff going on (involving social services and my mum) that has put me in the wrong frame of mind for the sort of work that's needed. (i.e anything that doesn't involve hitting things very hard with a hammer, or dismembering corpses with an axe ). Hopefully we're back on track now.

Rest assured that I will keep everyone here informed, regardless of the outcome - look out for 'my guitar is matchwood' on youtube shortly after I try stringing it up...

SteveF

Looking fantastic. 

Misterg

^Thanks!

So to finishing...

I've used Tru-Oil previously on my Firebird and my Telecaster neck. I liked it for necks, but didn't want to use it for the acoustic body. Having never used shellac for anything other than sealing knots before, I decided that I wanted to try and French Polish the body.

There are many, many articles and videos about the process that I read and watched diligently, but the two most useful resources that I found were an article by Bob and Orville Milburn:

 https://www.guitarsint.com/article/Introduction_How_To_French_Polish_Classical_Guitars

 And a video series on Youtube by Pablo Requena: https://youtu.be/Uf4z14Vjkxk?si=GRD5cKGtSjWxPF1m

These were broadly in agreement with each other (which is something of a miracle as there are many, many different approaches!). 

I was intending to use epoxy for grain filling the rosewood, but after trying out both the epoxy and the shellac / pumice method on some offcuts, I decided that the epoxy process was a bit too committing, and sanding back the epoxy was too much like work as I find it clogs the paper badly (West System).

So... Three coat of thinned shellac wiped onto the body to seal it, using a new, clean cloth for each of the bindings to avoid transferring the colour from the rosewood into them.

After a few more coats on the bindings to protect them from staining I set to work with a cotton pad, alcohol and a small amount of pumice powder, working it into the surface to generate a wood dust slurry that stuck in the pores. (I was following the process in the Milburn article).

It's a gradual process that you can take your time over and stop at any time (unlike the race against time to spread epoxy).

After the first session:

I quickly learned that there is only so much that can be done in one session - there comes a point where the only thing you're doing is moving the slurry around without any actually staying in the pores. Far better to stop, let everything settle for a few hours, and then come back for another 10 minutes.

When you think you're done, and you spot an open pore, it's easy to come back and spend a few minutes working that area to fill it in. Altogether a more relaxed process than epoxy.

This is what it looked like with the grain filled:

The residue on the surface needs to be removed (and the bindings cleaned) before finishing. It could be sanded, but after trying that in a few areas, I changed to just wiping it off with alcohol.

As long as you don't try and do too much at once, or get the surface too wet, it works nicely. It probably leaves more of a texture on the surface than sanding would, but I'm OK with that - it's not a dining table 

So then began the cycle of French Polishing:

The first few sessions are without oil, then I started using just a drop of olive oil each time I charged the pad. The shine on the guitar starts to build quickly, and then all the surface flaws really start to show!

I sanded the top back several times in different places to steam out small dings and scratches that had gone un-noticed on the unfinished wood. The beauty of Shellac is that you can work on these areas until they catch up with the rest of the surface and it blends in seamlessly. I also completely sanded the back as it became apparent that there was a line of grain filling residue that hadn't been completely cleaned off.

I'm about half way through the 'bodying' phase of polishing and the wood in the guitar already looks superb - I don't know what it is about shellac, but it really seems to make the wood glow. No decent photos yet, but this might give you an idea:

fastonebaz

Tremendous work there.  

Jez6345789

Fantastic work
I do think the epoxy works but probably favours a commercial environment as a time saver. 
I have used Z-poxy on cocobolo as it was recommended as it stops the red elements merging out the grain pattern so keeps it more defined also the amber tint in that enhances that type of wood. I was talking to Ken Parker at a guitar show last year and he thinks the West System is French Polish for the modern luthier LOL but he is Ken Parker. 

I think you have made the right decision and the results speak for themselves keeping it old school on a personal instrument when you are not running against the clock gives a whole lot of satisfaction and as you say that glow.

thanks for sharing the journey look forward to more progress

Misterg

Thanks both

Jez6345789 said:

I think you have made the right decision and the results speak for themselves keeping it old school on a personal instrument when you are not running against the clock gives a whole lot of satisfaction and as you say that glow.

Thank you - I'm sure I could have made the epoxy work, and would have got there quicker, with a glass-smooth surface, but it didn't feel like the right thing to do (for me, at the time). Despite the apparent tedium of the French Polishing process, I actually find it quite enjoyable and, as you say, immensely satisfying to see the finish develop.

I will keep you all posted!

Misterg

Right, time for an update:

I carried on the 'bodying up' phase for a total of about 10 sessions of polishing. I was aiming to do two sessions per day but sometimes I only did one session, and a few times, life got in the way and I didn't do any.

As Pablo Requena says in his video at this point, the guitar looks really good, until you look at it closely. While very shiny, the surface has a texture to it which you can see when it catches the light. It's really highlighted here over the complicated grain pattern in the top.

I wet sanded the whole guitar back with 2400 grade micromesh (equivalent to about P1500 grit) using white spirit as a lubricant. Sr. Requena does the sanding dry, but the abrasive kept clogging when I tried - perhaps I needed to let the shellac harden for longer. Using white spirit as a lubricant stopped the clogging but did make it harder to gauge progress until the surface dried.

Before flatting:

After:

My approach to cleaning after grain filling came back to bite me a little here: There were places where wiping back after grain filling had left depressions in the surface that were too deep to sand out. The process of flatting the surface off left a white residue in these places. This was mostly just the odd spot, but one edge of the lower bout was quite bad:

I suppose I could have gone back to pumice powder and filled these in, but didn't really feel inclined. Luckily Sr. Requena addresses this issue too: A little bit of alcohol on a finger tip rubbed over each spot is enough to re-melt the shellac dust and get rid of the white colour.

This is the same area after that treatment. I'll take that!

Then it was back to adding shellac again. After another 5 or so bodying sessions, I'm starting to think that I'm approaching the finish line.

I've got a holiday next week, so I'm thinking I might get another 2 or 3 bodying sessions in, then it can harden while I'm away, ready for 'spiriting off' when I get back (then it's another week, or so for it to harden again).

While this has been going on, the bridge has been getting the same treatment.

As mentioned previously, I'm finishing the neck with Tru-Oil. The mahogany responded beautifully to the same approach that I'd used before - sanding the oil in with progressively finer grit paper and polishing off with a coffee filter. However I simply could not get a decent finish on the rosewood headplate. No matter how much I tried, I simply couldn't get a couple of grain lines to fill - on the left hand edge of the headstock:

I abandoned the sanding approach here, and just kept coating the headplate with Tru-Oil. After a dozen or more coats, I think it's pretty much there now. (I might give it a light flatting and another coat.)

While I was messing with the headplate, I managed to ding the back of the neck quite badly

It steamed out OK, but frustrating, none the less!

I'm really looking forward to putting this together.

Thank you for reading if you got this far!

digitalkettle

Very impressive...bit late but: subscribed!

fastonebaz

At first glance in the latest I panicked thinking,  oh know he put the neck in upside down, but then I quickly realised it was just a holding feature.  Phew!  Heartbeat restored.  The logo in the headstock looks perfection.  Soo looking forward to the first audio and playability testing..

Misterg

fastonebaz said:

At first glance in the latest I panicked thinking,  oh know he put the neck in upside down,

Ha ha - yes, I'll admit that the cut-out for the 'handle' should have been on the other side

fastonebaz said:

 Soo looking forward to the first audio and playability testing..

You and me both!

If it doesn't disintegrate when stringing it up, there's the question of whether it will sound any better than a cigar box and an elastic band. The suspense is killing me!

DartmoorHedgehog

Wow, that looks fantastic @Misterg ;
I'd completely missed that this had gone from "thinking of building" to "actually building"

I don't think you need to worry about the sound. My only acoustic-building effort was replacing the top on a fairly cheap 12-string that was folding up and couldn't be tuned to standard pitch anymore.  I purposely erred on the side of over-engineering for my new top because I wanted to make sure it fixed the problem but even then it sounds better than the original guitar did. You look to have done a much better job than I did so I'm sure yours will sound superb.