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Norman
(@norman)
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30/06/2020 5:17 pm  

Hi, I am making my first guitar, a classical one. I have Bogdanovich's book but his guitar is far too complicated except for a masochist! I am basing mine on his but leaving out all the fancy bits.

I have got the body closed in and after trimming the front and back I will be doing the binding.

I do not want to spend a lot of money on tools as I may not make another, I'd like to see how this one goes first.

I need to cut the rebate for the binding but a rebate cutter for a router [I have access to one) is rather expensive. Can anyone suggest how I could do this? I am thinking of making a cutting gauge but the wood of the guitar front is quite hard and I cas see myself struggling with this. Any suggestions would be gratefully received. Thanks, Norman


mark bailey
(@markbailey)
Guitar Making God
Joined:2 years ago
Posts: 455
30/06/2020 5:39 pm  

Hi Norman - welcome! Sounds like you are on the right track -

I always route the channel with the proper binding cutter as I am rather spoiled and fussy - I cannot really recommend another way as to me they are very tricky and take way too long...

The best advice I can offer is probably just to simply skip the binding...

No binding it is quite trendy nowadays...and saves a lot of hassle!

Here is an offer: If you join up as a Premium Member I can lend you one of my old binding cutters (I have 3 acquired over the years!) - I have extended this offer to some other of my students - it is something I have done before. We did hire out some tools for a while but there was not enough uptake...

Hiring the binding cutter set is one the ideas...

Let us know what you think?

Anyone else got any suggestions?

Measure twice, cut once...


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Norman
(@norman)
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30/06/2020 8:33 pm  

Hi Mark, thank you for your reply. I quite like your idea of no bindings but I have two problems. My daughter, who may well end up with this guitar as I can't play, asked about the bindings as she obviously feels that they are important. Secondly, my kerfing stands a little proud of the sides leaving a small gap between the top and the sides, so I have to do the binding to eliminate the gap. 

I made the sides using 4 layers of .6mm veneer. The outer layer is black walnut. When I took the first one out of the mould it had black stains on it. I thought that this was mildew but when I got a spot of pva glue on the back, fortunately the inside, I found that that also stained black. I have never come across pva staining wood before.

Norman

 


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mark bailey
(@markbailey)
Guitar Making God
Joined:2 years ago
Posts: 455
01/07/2020 8:55 pm  

@norman Yes PVA can stain the wood...I'm not sure why this happens. We use a different glue for laminations...I will check the details and add it here tomorrow...meanwhile did you see the livestream today? I did some info on binding you might be interested in:

 

Measure twice, cut once...


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Norman
(@norman)
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02/07/2020 8:08 am  

Yes, I watched the livestream. Very informative, thanks,


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darrenking
(@darrenking)
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04/07/2020 10:39 am  

Hi Norman,

I haven't seen PVA stain walnut before but it is an indication that, whilst most PVAs are white (unless they are dyed yellow ie Titebond) and smell pretty much the same, they can have significantly different chemical properties. The main one which tends to crop up with wood working, especially veneering, is the pH. PVA is acid and the pH value is normally somewhere between 4.5 and 6. At the lower end of this range PVA will react with the sugars in some wood such as maple, sycamore etc and produce a pink or even purple discolouration. It could be that your adhesive is at the extreme of acidity and this is causing the problem.

As Mark mentions, the adhesive that we have been using for laminating backs and sides is a urea formaldehyde resin which comes in liquid form and is mixed with a powder hardener and a powder mineral grain filler to prevent any bleed through to the surface of the veneer. The key advantages of this over PVA is that it does not have a high water content and that the cure process is entirely a chemical reaction within the glue line rather than the process relying on the water in the glue line being absorbed by the veneer. This means that once the adhesive has fully cured the process is over whereas with PVA you should still wait for all of the additional water that has been absorbed by the veneer to evaporate. This can take many days and is very difficult to monitor accurately. UF resin will take 24-48 hours to fully harden (6-8 hours in the press) but during this extended cure the veneers are going through far fewer changes than if they were giving up 20% of their weight in water. The other advantages of UF resin are its long open time, which means that the lamination has plenty of time bed down nice and tight before the adhesive starts to grab, and that it dries VERY hard, so hard in fact that you have to be really careful of any squeeze out as it can form scalpel-sharp edges and cause human body leakage!

I have tried numerous different lay ups of veneer and I am now using five layers with only the central one going cross grain to give additional strength and stability to the construction. It is also noticable that using similar, if not the same, species for all layers does produce a more pronounced 'ring' to the finished component. Now, whether this is desirable or your preference is for an acoustically neutral body construction is another thread all together I think! I know of one German guitar maker who laminates his sides to between 4mm and 6mm to ensure that they add almost nothing to the resonance of the instrument so as to concentrate all vibrations to the soundboard.

The adhesive that we use is Prefere 4152 resin, 5602 hardener and 5912 filler powder. I you PM me I am happy to send you a sample to try out.

Cheers and good luck

Darren


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Norman
(@norman)
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04/07/2020 3:47 pm  

Hi Darren, thank you for you offer but I won't take you up on it right now. I used pva because that is what I have and I always use nowadays for wood projects and have never had a problem before. Many years ago I tried Aerolite glue with little success, I don't think that I clamped it well enough. What about cascamite? I have used that and it always proved to be good.

I have been thinking ahead and if I do make another guitar I might try making the sides with a single thickness of 2.5mm veneer.  I will have to make a bending iron, that will be fun!

I got around the problem of the staining by using an ebony stain to hide the marks. This guitar is not going to be perfect but I am getting better at it as I go along. I have no machinery and have to do everything by hand. I have just come in from planing the head of the neck to thickness and am pleased at how I am getting better at it. Thanks for your tips. Norman


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