Making Master Guitars

[needsmorecowbel]

Just started Reading Courtnall's Book: Making Master Guitars...

I have already joined some Indian Rosewood. Overall Very happy with the join...However i did not wipe the join with acetone prior to joining. I just very carefully wiped it with an old (but clean) bonds singlet when it was fresh off the shooting board. Should i Cut down the join and rejoin or leave the join? I did not join the book matched Rosewood in the traditional way (Grain Curving inwards and meeting at the centre). I chose the less traditional grain configuration because doing it this way left less wastage:

What would you do?



Stu

[Bruce McC]

Stu

You should be ok mate, I think the Bonds singlet will save you
but I can't follow your logic on the wastage, are you trying to wind
us up?

[Dominic]

Stu, I'd redo it just for the look. I wouldn't sacrifice aesthetics to save a few bigger off-cuts. A guitar is far more valuable than a few head-plates or other trim. I usually glue up my panels right off the plane and rarely use acetone.

However before you redo the join, reading in the Gore/Gilet book, they recommend leaving a slight gap in the middle of the panel when jointing and not a seamless light free joint. The reasoning being that the wood absorbs water and swells when being glued and causes a slight convexity in the panels which can pull the ends apart if the plates are jointed seamlessly. The process is to get a seamless gap and then take a couple of very light passes in the middle 3/4s of the plates. This makes sense to me so I thought I would try this technique next time I glue up plates.

Good luck with it.
Dom

[charangohabsburg]

I like the "reverse" look, I don't find the one or other way would be unaesthetic. If you don't like it just redo it as Dom said.

There's a controversy. There are luthiers who even strongly recommend to not wipe the surfaces with acetone prior to gluing but rather join freshly exposed surfaces. Others strongly recommend to wipe joins with acetone.

Most luthiers never wiped down their (Indian) rosewood joins and everything holds together just fine, but some had bad luck or did not glue up the panels right after planing.

[needsmorecowbel]

Thanks for the responses guys. That is an interesting idea Dom! I have barely had a chance to have more than a flick through the Gore/Gillet books. I really actually don't mind how it looks in reverse but it could really be something to regret down the line. Asfar As I am new to hand planes and wood working I wanted to leave a lot of room to move as I still don't have the complete confidence to say i will be able to join the wood with a flawless join within 6-8mm of planing haha. My first highly figured back was Dreadnought size to start with and by the time i was happy with the join it was down to classical size (WHOOPS). I have not made the same mistake since and do not intend to any time soon. Cheers Markus!

[J.F. Custom]

Stu,

Aesthetics aside, EIR will vary piece to piece in it's oil/resin content anyhow - are these particularly oily to the touch?

Don't forget you will have a bracing strip running over the join, as well as transverse braces that will all support it further. Perhaps you could wipe the area under these just prior to gluing.

As mentioned though, some do some don't.

Jeremy.

[Dominic]

Stu, there is a really good video showing how to control the plane while jointing tops and backs. I am pretty sure it was the Kent Everett dvd. Was a light bulb moment for me watching and I can now do very quick flat joints.

So the trick is that if you have slight gaps at either end which is usually how it goes wrong, you put more pressure on the toe of the plane going into the cut and then shift back to the tail as you exit the cut. You are effectively trying to make the plane move in a curve opposite to the convex plates but of course your blade stays in contact with the plates. It sounds weird but try it on some scrap and you'll see it is very easy to go from a convex to a flat join.

And make sure you plane is very sharp and dead flat, I stuffed around for ages when i first started with a new Stanley #5 that had a concave sole. I couldn't work it out until I noticed it didn't sit flat on the bench. When i got a decent plane and learned how to sharpen it I had no more problems and now with this technique I find it very easy and fast to make adjustments and get a good join.

Hope this helps you save your precious tonewood from turning into a pile of curls on the floor and forcing you to make more parlour guitars.

Cheers
Dom

[ernie]

The camp that believes in a slight gap before jointing must have been a cabinetmaker in a previous life , that is typically how wooden boards are joined . I always opt for a seamless flawless joint with no gaps using a large LN shoulder plane and a shooting board. I don/t think introducing stresses into the joint will help in the future for the center seam especially if it is a domed EIR back that is only 2.5mm or less. Cycles of dryness and humidity can wreak havoc on a stressed join. . My 2 cents.

[Mark Fogleman]

Some good advice I follow is here:
http://www.smithandcompany.org/Tropical ... gTrop.html

Pearls:
Allow the adhesive enough time to soak into the edge before joining. This prevents glue starving when it happens after the joint is clamped.

Too much clamp pressure can weaken the bond. A near perfect joint needs very little clamp pressure.

Don't use a solvent prior to adhesive. It soaks into the wood and can weaken the bond. In some woods, solvents can actually increase the amount of oil present on the edge. Freshly machined surfaces are best. Ebony does best with light sanding prior to bond.

Don't use a solvent to clean the drips around the joint. It can weaken the bond.

[Bruce McC]

Hi Stu
If your soundboard ends up being a few mm's too narrow after jointing, just
add two small pieces (from the offcuts) on either side of the lower bout area.
With any luck most if not all of the "added wings" will be cut away when you
come to cutting the purfling and binding channels.
Part of the skill is learning how to cover up unwanted outcomes, ie mistakes.

[woodrat]

Unwanted outcomes sounds so much better than mistakes Bruce!

[ozwood]

I like to call them" forced opportunities to make a Feature "

[needsmorecowbel]

haha funny bunch!

[Kim]

Gentlemen, gentlemen please...MISTAKES!!???

As custom builders our instruments represent a collection of spontaneous freestyle progressions carefully orchestrated to inspire a symphony of innovations in aesthetic design and functional development captured in unique sculptural expressions of passion, style and distinction which reflect the individuality and astute judgement of those who chose play them. burp!

(I also do wine labels and greeting cards if anybody is interested...)

Cheers

Kim

[Cookie man]

Wow Kim....where did you say you worked? Sounds like politician material there....

Although, that is a good point... one might say they are slight alterations in your/the customer's vision of what the instrument is going to be!

[kiwigeo]

Some good advice I follow is here:
http://www.smithandcompany.org/Tropical ... gTrop.html

Pearls:
Allow the adhesive enough time to soak into the edge before joining. This prevents glue starving when it happens after the joint is clamped.

Too much clamp pressure can weaken the bond. A near perfect joint needs very little clamp pressure.

Don't use a solvent prior to adhesive. It soaks into the wood and can weaken the bond. In some woods, solvents can actually increase the amount of oil present on the edge. Freshly machined surfaces are best. Ebony does best with light sanding prior to bond.

Don't use a solvent to clean the drips around the joint. It can weaken the bond.

Reading through the link I think it applies more to epoxy resin glue than PVA/AR or hide glues which are more commonly used on back and top joins...they specifically mention using solvent to clean up drips...applicable only to epoxy glues. Hide and AR/PVA glues are water soluble.

[Kamusur]

Ahh Kim



Steve