River guitar - Scratch build

[Ricky]

Hi All

My next build is well underway!

This time it is a resin 'River Guitar' based on the Les Paul shape.
The whole thing is an experiment as I have not worked with clear cast resin before although I have plenty of experience with epoxy resin working on too many yachts over the years.
It was watching a video of Ben at Crimson Guitars that forced my hand on this one.

I managed to find a nice plank of oak with a live (waney) edge - not the most interesting edge but it will do.
The resin I used was Glass Cast but I believe that most of the clear resins will give the same results.

First job was to cut the oak to rough LP shape and build a mould matching the shape as closely as possible (resin is expensive and you need to minimise wastage. The live edge of the oak was coated in resin and 24ct gold leaf applied.
The mould is lined with plastic tape to ensure there are not any leaks and also to make it easy to separate from the guitar body

I managed to pour it in one go but I failed to seal the oak properly first which meant I got some bubbles trapped in the river. Once cured, I drilled the bubbles out and patch filled them and they disappeared.

Shaping the top of the LP shape was hard work as the edge 5/8inch is flat and the body bulge then starts. Sanding resin is hard work even with 40 grit pads and a belt sander.

Pickups are Warman Drivetrain hb's coming in at 29.87kohm each. I have no idea what this will sound like but I am also fitting dpdt switches for series/parallel choice on both.

Bridge will be a home-made thing using a maple and walnut lamination. I will turn the studs on my lathe from brass.
So far I am undecided on trapeze or stop tailpiece.

The neck is being made from American Tulip wood (not Poplar!) with an Ebony fret board and Jescar Gold EVO frets.
Tulip wood may be an odd choice but as I said, it is an experiment in many ways.
Currently I have cut the neck blank roughly to shape and will fit the truss rod tomorrow.
Locking tuners and bone nut arriving monday.

The body is fully sanded and painted black using Aerocolour airbrush paint, ready for its next coat of resin. I will take photos tomorrow and post them.

Couple of shots of the body casting. Sorry for the quality.

Cheers
Ricky

[Fretworn]

I have zero experience with resin. Will it be easy to route for the pickups etc, especially as the routes will be both resin and wood? I know woodturners seem to have no issue, but a lathe and a router are very different propositions.

[Simon Barden]

Two similar builds happening at the same time! https://www.buildyourownguitar.com.a...ad.php?t=10921

You’ll probably need to set the bridge posts in with resin as I doubt you'll be able to simply hammer them in to an undersized hole, as the resin is likely to crack. But I’m sure you’re already familiar with these sorts of things.

[Ricky]

Yes Fretworn. routing for the pickups and neck etc will be challenging. The problem happens when you transition with the router from resin (very hard) to the wood (softer) and the router bit bites in a different way. I will just take it extremely slowly with the small router/trimmer and use a template guide. I will keep all the cable runs in wood which will mean repositioning the switch from the top shoulder to somewhere below the bridge - not sure yet.

Simon. You are right about the studs in resin - cracks are not a good look! I am building the bridge myself so I plan to make it wider than normal and will 'bridge' the resin so the studs will probably go into the wood as well. However, I do have that problem with the strap button and the screws for the pu surrounds.
Do you think I could set those screws in resin or will the screws be able to cut their own thread (with a pilot hole) or should I tap a thread and use small bolts (which I have)??

These are the sorts of issues that I enjoy! Easy would be boring.

Cheers
Ricky

[Simon Barden]

JimC knows far more about this than I do. I know he’d recommend drilling and screwing into partially set resin (and then remopving the screw so it doesn’t stick), which is a bit late now for your body. But I assume you could drill a bigger hole than the screw size, fill it with more resin and do the same when that’s partially set. I’m sure he’ll be along soon.

[JimC]

I think I would tap the holes and use machine screws if I had the tools and skill set. That's got to be the best result. Be worth casting a little bit of resin in a pot to practice cutting the threads if you haven't done it before in that material.

As far as bridge posts, yes, I think I'd drill out fractionally oversize and set them in fresh epoxy if they don't end up being in wood. A mad idea has me imagining reshaping holes in the river to an eddy shape, not round, and then using white coloured epoxy to fill the holes so it looks like white water rushing round the posts. Maybe my imagination is out of control?

I'm no routing expert, but I can think of a few occasions where I wished I'd made a jig that restricted movement in every wrong direction, no matter how unlikely, but I don't recall an occasion when I said to myself I wish I hadn't made that complex jig that made it impossible to go wrong.

[Ricky]

Thanks Jim and Simon.
I have drilled into resin soaked mahogany and then screwed in coach-bolt type screws but that was on a rebuild of a 1964 50 foot ketch.
Slightly different scale of things.
I have also drilled and tapped into resin type material but never a clear cast resin so your idea of doing a test piece first is the way to go.
It just so happens that I have a cup with about 3/4 inch of resin setting right now (left over from coating the back of the body - photo below).

This resin task is all a waiting game. Resin goes off overnight but takes a couple of days to build any sort of structural integrity.
Patience is not my strongest point!

Bridge posts.
Yes, your imagination is out of control but in a really good way. I am now considering that . Another thing to practice first!

I have found that whenever I rout and the bit bites badly, it is always in the wrong direction and never into the safe area. For this reason I will use a template. It would not be so bad if routing into wood as I would use a chisel to create a trough on the outer edge and then guide the router toward that trough if that makes sense. A chisel is no use near resin though.

The photos below show the back with a coat of resin applied. It shows as uneven as there is a different rate of soak into the wood.
The dots around the horn are bubbles which require popping every hour or so for about 4 hours. It will require at lease 2 coats of resin before I turn it over and do the same to the top.

Cheers
Ricky

[cadebengert]

Looks sharp! Word to the wise as I am doing a similar build right now: make sure you wear safety glasses and a mask while routing the resin. It will throw chips like a mother. Going slow is definitely the key. You are totally right about the transition between resin and wood. The router will tend to jump and throw itself. Made my pickup cavities... interesting. Take it slow and you should be fine.

[Ricky]

Thanks Cadebengert!
I couldn't believe it when I was writing my build diary - never seen a river guitar on the forum and then 2 on the same day - and both single river Les Pauls. What are the chances??!!

I know what you mean about the chips. I have had that on boat hulls too many times.I will remove most of the material with forstner bits or cabinet hinge bits using the pillar drill first and then use my trimmer/router slowly with a pattern clamped in place.
At the moment I am adding the layers of resin to the body top. It is arched so just poring the resin was not an option really. Slow but I have the time,

Good luck with your build - I will be watching.

Cheers
Ricky

[FrankenWashie]

D.A.N.G!!
The FrankenLab salutes you both! Wonderful stuff @Ricky, @Cadebengert!