Classical Guitar Construction

[zendo]

I am an independent sort of bloke which is why I stubbornly make this guitar by myself However I am stuck with how to effectively and more quickly shift the Indian Rosewood classical guitar back down to a reasonably good sounding thickness. No doubt when I get to the sides I will have the same problem. The wood is currently about 3mm and according to my notes should get to between 2.5 and 2mm no less. I have tried sanding (hopeless), scraping with scrappers in a veritas holder (much better), planing took out chunks.. I have just bought a Veritas Scrapper Plane but have baulked at the honing stage which I always find difficult (given the cost I will eventually make good use of it) ... it seems shaving from 3mm to 2mm is a very slow process.... I could use a thicknesser at a workshop I can use but I don't dare go there.... help... any ideas welcomed... hello Kiwigeo... how's the Lute going? I am playing mine and sometimes wish I had stayed playing classical guitar as well.

[Paul B]

Sounds like you need to construct a thickness sander, or find someone locally who will either let you use theirs or do it for you.

[charangohabsburg]

[...] Indian Rosewood classical guitar back down to a reasonably good sounding thickness. [...] planing took out chunks..

Hi Zendo, planing across (or at least diagonally to) the grain helps and lets you get down close to target thickness quite quickly. Be careful though to get the thickness reasonably even, I find it easy to get it too fast uneven!

[...] I have just bought a Veritas Scrapper Plane but have baulked at the honing stage which I always find difficult [...]

I also have the Veritas scraper plane (the "big" one) and never bothered a lot with honing, I find it much less critical than a normal plane blade to produce a nice surface.

[...] it seems shaving from 3mm to 2mm is a very slow process.... [...]

Using only the scraper plane would not be the fastest way, but doable. If your scraper plane is not the one with the wooden handle it certainly will not be much fun and previously planing across the grain with a normal plane would be almost a must, in my opinion.

[...] I could use a thicknesser at a workshop I can use but I don't dare go there....

A thickness planer or a thickness sander? I think thickness planers have been used for such tasks, sticking the back respectively side veneers to a backing panel, but I believe this can still be risky or even dangerous not only for the wood. If I were you I would not try to mess with thickness planers and thin wood. If it is a thickness sander I have not said anything.

Cheers,

[Bruce McC]

Zendo......principles are fine but they get you nowhere.
A thickness sander will save you lots of stress and grief.
You can use your hand scrapers to finish off the job.

[kiwigeo]

I am an independent sort of bloke which is why I stubbornly make this guitar by myself However I am stuck with how to effectively and more quickly shift the Indian Rosewood classical guitar back down to a reasonably good sounding thickness. No doubt when I get to the sides I will have the same problem. The wood is currently about 3mm and according to my notes should get to between 2.5 and 2mm no less. I have tried sanding (hopeless), scraping with scrappers in a veritas holder (much better), planing took out chunks.. I have just bought a Veritas Scrapper Plane but have baulked at the honing stage which I always find difficult (given the cost I will eventually make good use of it) ... it seems shaving from 3mm to 2mm is a very slow process.... I could use a thicknesser at a workshop I can use but I don't dare go there.... help... any ideas welcomed... hello Kiwigeo... how's the Lute going? I am playing mine and sometimes wish I had stayed playing classical guitar as well.

Hi Robert,

On my way to work but just saw your post while sitting here at the airport.

Nothing happening with the lute as I still need to procure/make pegs. The project is on the back burner at the moment.

Re working IRW before I got my drum sander I used to rough work IRW backs a sides with a bench plane. IRW tears out badly if you plane in the wrong direction but usually you can plane it in the other direction with success if you use a really sharp blade in your plane or even using a toothed blade. I also found planing at an angle to the grain direction often worked best. Note that when working a glued up back set youll need to work each half of the back in opposite directions.

Cheers Martin

[zendo]

ok so I bought the carbatec drum sander and I like what it does very much as you can imagine after all that scraping. Getting it set up is an ongoing concern and eventually it will be ok because I am learning a lot about the machine. My first sanding effort with an Indian Rosewood back didn't work so well, I think because the drum is still not level and also because I took too much off too quickly and unevenly (1.3mm more or less around the outside to 2.5 more or less near the centre - although not consistently the same thickness across the wood). I notice in my book thicknesses on classicals from 1.0 to 2.5mm although I am supposed to be making a Fleta copy which is 2 to 2.5. However I am going to keep going and make up a guitar which will show all my errors. Even though it's using my reasonable stock of wood. I just want to get the "prototype" done because I can see the valuable learning involved. I will post a photo of efforts so far. Any comments welcomed as usual.

[graham mcdonald]

The trick to the Carbatec 16" sanders is not to try to do too much at one time. On a glued up guitar sized back (or soundboard) I would adjust the wheel no more than 30° per pass, and less if it is an oily piece of rosewood. I suspect they don't come from the factory with the feed belt and drum exactly parallel. I shimmed the outside of the feed belt support about 1mm originally and probably should do it again. I think even when they are well set up there will be some flex in the drum and some fraction of a mm difference in thickness from inside to outside. I never really expect them to sand a back or soundboard totally evenly. For each adjustment of the wheel I run the piece through twice, turning it around for the second pass so the sanding to each edge is even, but the centre will be a bit thicker, which I figure is usually not a bad thing anyway.

wouldn't do without it though!

cheers

g

[ScottC.]

A Safe T Planer makes quick clean work of EIR
https://store.schoolspecialty.com/OA_HT ... tem=349134

[zendo]

The trick to the Carbatec 16" sanders is not to try to do too much at one time. On a glued up guitar sized back (or soundboard) I would adjust the wheel no more than 30° per pass, and less if it is an oily piece of rosewood. I suspect they don't come from the factory with the feed belt and drum exactly parallel. I shimmed the outside of the feed belt support about 1mm originally and probably should do it again. I think even when they are well set up there will be some flex in the drum and some fraction of a mm difference in thickness from inside to outside. I never really expect them to sand a back or soundboard totally evenly. For each adjustment of the wheel I run the piece through twice, turning it around for the second pass so the sanding to each edge is even, but the centre will be a bit thicker, which I figure is usually not a bad thing anyway.

wouldn't do without it though!

cheers

g

Hello Graham, Actually my new machine should have a shim on the other side because B (terminology from the manual) is about 1 or 2 shims width greater than A but the method of adjusting is to loosen up the unit and try it without shims, which would be impossible to get in on that side anyway. I still haven't mastered it but I am taking your advice about passes and having the knowledge that a glued up back is best thicker in the centre anyway. Great advice.

[kiwigeo]

A Safe T Planer makes quick clean work of EIR
https://store.schoolspecialty.com/OA_HT ... tem=349134

Useful for sides but not so useful if you're thicknessing a glued up back.

[ProfChris]

I found a toothed blade for my plane made a huge difference. Probably the best solution for thicknessing with hand tools. I also have a Record scraper plane, which works well but is much slower.

Toothed blade down to nearly the thickness, scraper plane or card scraper to finish off. Mind you, I only do soprano ukes, so there's far less work involved - 20 mins or so to thickness a back.

[simonm]

I found a toothed blade for my plane made a huge difference. Probably the best solution for thicknessing with hand tools. I also have a Record scraper plane, which works well but is much slower.

Toothed blade down to nearly the thickness, scraper plane or card scraper to finish off. Mind you, I only do soprano ukes, so there's far less work involved - 20 mins or so to thickness a back.

+1 for this.

A toothed blade in a block plane plus a cabinet scraper is amazing. I suppose in a no 3 or 4 it would be even quicker.

[Dominic]

I hate doing IRW in my sander. I go 1/8 turn each time and put the board through twice before lowering the drum but still have trouble. After gumming up two belts on 2 B&S sets the other day I still had one 4.5mm back to finish. So I spent time and set up my planes really well and hit the back across the grain and it was actually faster than using the sander. I can pass it through the sander when I am closer to final thickness to take out any bumps and lumps but it may not need it.

I am happy to put tops through the sander or most other B&S woods but IRW is a belt killer.

Dom

[Trevor Gore]

I've tried toothing planes...nowhere near as quick and clean as cross-grain planing. Use a standard angle plane, preferably a #5 or larger, sharpen the blade so it has a crescent shape (scrub plane mode, as per "the book") and off you go. If you have a #5 1/2 it's quicker still. If you want to do sides the same way, place them side by side and use a #7 and plane across them both at once. The length of the toe on the #7 is sufficient to hold down the second (far) side. Plane a small bevel on the exit side of the panel to prevent split-out. With a bit of practice you can get both backs and sides really flat and even, which is easier with a wider plane. If you want, you can finish in-line with a high angle plane. I use either my special high angle #6 (60 degree) or the Veritas low-angle jack with the blade sharpened to a 50 degree bevel to give a 62 degree cutting angle.

And yes, I do have a few planes (and spare blades).

[EricDownunder]

If anyone is interested I tried an adjustable panel beaters body file today used across the grain on tasie blackwood
with a join in the centre for a solid guitar, the grian was in all directions making it very hard with a very sharp plane, You know what I was impressed, no problems as long as I took care, I then left the job to my son-in-law who kept up the good work and finished with a panel beaters long 18" x 2" sanding plane and got a pretty good job and the final finish later.