Adventures in amateur luthery - another one.....

[sebastiaan56]

My latest effort. King Billy Pine top, Qld Walnut back and sides, Tassie Oak neck, Pacific Blackwood (Sollys Ebony) fretboard, bindings and bridge, Eucy burl for the headplate. 635mm string length, joined at the 13th fret. It is a bent top (not a pliage).

The guitar is a test of a number of ideas. Ive been making Mandolins and Mandolas with bent tops for a while and I thought it would be good on a guitar. Is it not a Maccaferri style pliage in that that soundboard has a much lower radius (28 feet). The QLD Walnut came from the Sydney WWW Show and so I had to resaw etc. It is beautiful stuff, It bends beautifully has a unique smell and the photos dont do the chatoyance justice. I was curious if I could bend the spalted bits. I can The top is 4 piece King Billy, I love the smell of this stuff. The Solly's Ebony is also from the WWW Show, it is much easier to work than African Ebony.

The soundhole placements were an attempt to get more sound out of the whole soundboard. It is braced with three transverse braces, the lower two are reinforced with CF tow. This has led to an unexpected problem in that instruments neck is pulling towards the body when it is strung. ie the string height at the 12th fret moves from 2mm to about 4.5mm. The soundholes weaken the sides and I thought the top would be able to handle the tension. It is 4mm all over but it flattens in the area between the first and second braces under tension. It seems KBP doesnt have the cross grain stiffness to hold the tension. I'll use a ladder brace for the next one. Ive tried patching inside with CF tow. It will be cured tonight so I will restring and see how it goes. If it doesnt work I'll give it nylon strings.

It still sounds very "new stringy" but has great volume and seems balanced across the register. I think this a half proof of concept. With a better bracing scheme and a Spruce top I think this will work really well. It think the concept will make a killer Mandocello.

[Allen]

Great looking instrument. Do you have any pictures of the insides during construction. Always good to see a bracing pattern even if it's not up to the job on the instrument in question.

Did you do the resawing on the Qld walnut? Most people won't even let it in the same room as their bandsaws. Takes the edge off tools quicker than anything I've worked with before.

[sebastiaan56]

Hi Allen,

I looooooove QLD Walnut, the colour, the grain, the chatoyance and I dont mind the smell. Its a bugger to cut but works well with very sharp tools. The B&S came from a 10mm slice off a slab. The sides were split on a table saw and I hand planed and used a cabinet scraper (Stanley #80, god's gift to woodworkers) to get it down to thickness, 2.5mm. I though the sides would crack as there are knotlets/eyes in there but they bent like butter. I bought up on slabs that were around and have an outdoor setting underway as well.

No bracing pictures, three transverse at the top of the lower, middle and upper bouts. 10mm high x 5mm wide, sitka spruce. Same on the bottom BTW.

[woodrat]

Well Done Sabastiaan, beautiful guitar and beautiful wood too... Allens right it is terrible on tooling but I have made one guitar out of it and it the best sounding guitar that I have made. I cant say that I especially like working it but the rewards are certainly there for perseverance. My walnut guitar had a 4 piece back because the wood just wasn't big enough. The shimmering figure was too nice to pass up so a 4 piece it was.

John

[John Maddison]

Hi Sebastiaan ... nice design & execution .... do you have a preferred supplier of the metal tailpieces in Oz? Thanks!

[DarwinStrings]

Regardless of the structural problem it looks a treat, that lack of hole in the board always give a guitar a interesting look and when it come to experiments, you don't get anywhere if you don't try. The fact that you are happy with the sound so far must be a rewarding feeling. Well done for walking out on that limb Sebastiaan.

Jim

[sebastiaan56]

Hi John FM,

I got the tailpieces here: http://luthierssupplies.com.au/product_ ... ts_id=1030 they are currently out of stock. Being Allparts it should be widely available.

Hi Jim,

I post learning experiences so that others can learn. Bob made a comment on KBP a while ago about it not being ideal for steel string guitars, on Steve Kinnaid's KBP thread I think. Anyway I thought a bent top would solve the issues, it doesnt, but that doesnt invalidate the bent top design.

Thanks John, QLD Walnut is the ducks nuts, I know Maton have used it a lot as well. Nice guitar!

[Bob Connor]

I didn't say it was unsuitable for steel string guitars Sebastiaan.

I don't think it's suitable for large steel string guitars ie dreadnoughts because it's not strong or stiff enough to span such large guitars. Once you start scaling things down everything changes making it very suitable for smaller bodied instruments.

I played a King Billy/Blackwood 0-18 down in Tassie a couple of weeks ago that is now sounding gorgeous three years on from when we built it.

I've built some lovely little 0 models with it and I'm about to start a KB and Huon Pine Terz.

So I love the stuff for steel strings - just not on a J-200

[Nick]

QLD Walnut is the ducks nuts,

What? it gets wet occasionally?

Nice job Sebastiaan, particularly interested to see the bent top, Maccaferri came from a Mandolin making background too, hence his use of the bend in the top (because that's the only thing he knew to do with a top). Pity your experiment didn't work as you had planned it. I know it would have ruined the thinking behind the top, but perhaps putting the old bigger transverse brace under the fingerboard end might have stopped the neck pulling up? Would have spread some of the load back past your soundholes & into the more 'solid' area of the sides (would have triangulated the loads). Or perhaps, as a few have been employing of late, some CF flying butresses back to the waist.
Anyway, certainly doesn't detract from the looks, may be worthwhile revisiting it at a later time & getting it behaving properly as it would be a worthy part of the collection.

[sebastiaan56]

Thanks for the correction Bob, thats the way I remember it now.

Nick, I reckon the buttresses will be the way to go as well as beefing up the sides, particularly around the soundholes. Rick Turner has mentioned using CF tow in purfling and around the kerfing. I have a couple of hundred metres so I may as well use it I want to keep the top a bit light on.

[Kim]

She certainly is a killer in the style department Sebastiaan, the QLD walnut is really beautiful.

Are you sure the problem is the soundhole/holes (you mention plural but I only see one) weakening the sides????

One comment from a novice about the bracing: 5mm x 10mm seems far too fine to me for the UTB. I would imagine it is doable with CF capping for the lower 2 but the upper transverse really takes a load in a steel string so I would think even more robust like 7mm x 12mm 'and' CF for that brace would be a good idea. As I understand you had left the top at the upper bout thicker to take the load. But even if the top were spruce (exception may be red spruce with lots of hard brown winter grain) I think you may have struck trouble. IMO the upper transverse brace needs to be considered as the most structurally important of all the braces, especially in a ladder brace configuration.

Fingers crossed that the tow reinforcement you have applied solves the problem for you.

Cheers M8

Kim

[J.F. Custom]

Hi Sebastian.

Late on the uptake here I realize, but that's certainly a stylish guitar. Worth the experiment and, as is sometimes the nature with experiments, worth the effort to 'refine' and get 'right'. Well done.

+1 here for Qld. Walnut too...

Jeremy.