Archtop build number 2.

WezV

starting to get into the technical bits of tone shaping an acoustic chamber and taking some measurements as I go.  I now have parallel braces glued in

The top now has 2 braces in it.   On my first archtop i went for big sturdy braces as i primarily considered it an electric instrument. It worked well, but I was more focused on structure than tone.  This time I will be tap tuning as I go, starting with the top and braces

I am tap tuning.  So hold the guitar by a node where it will move less, then tap with a knuckle in the bridge location.  I am measuring using a strobotuner with contact pickup plugged in.   Also using Spectroid app on my phone to doublecheck  the readings.

The peterson tuner shows a C# in the 4th octave.  Spectroid shows the strongest peak at 278Hz.  That's pretty much a match on the readings.   Good to know my methods are giving consistent measurements

I can now control the tone with a few changes on the top.
-Increasing F-hole size will raise the pitch, but too much will start to lose warmth and projection
- shaving the braces will  lower the pitch, but need to make sure structure isn't compromised.  The sides of the braces can be shaved to mimimise loss of stiffness
- tapering the plate from thick in the center, to thin at the edge and adding a recurve will lower the pitch, but increase projection.

That's the top. It will change again when glued to the sides and when the back is on, getting higher with each addition.  Frankly I'm not totally sure what I am aiming for at this stage, just keeping track to see how it turns out.  I'm not going to touch the recurve until its a complete box

Jalapeno

WezV said:

davros said:

They are some really elegant f-holes!

I do like to keep them quite slim and elegant, but there are a few things to consider that may still see them open up a bit more.

the main considerations, according to Benedetto, are : 
1 - space between f-holes.  too close will reduce the main are of the top
2 - narrow f-holes can choke the acoustic sound and reduce its responsiveness
3 - Wide f-holes can reduce protection
4 - the mid points should line up with the bridge

I think I have the positioning pretty good on this one. There is a risk they are too narrow at the moment, but I would rather that, and be able to tweak as I go than have them too wide already.


I am not going to bind them. i much prefer un bound f-holes on this kind of thing.   I'm also not going to do them big enough to pass pots and wiring through... so will need an access port on the back

Black marker pen is useful for finishing unbound f-holes

Progress looks ace !

WezV

I like to see the grain in the F-holes - but black marker pens are certainly useful for lots of things

WezV

Not updated in a while, but it is progressing.

Top has been glued to rims.   Routed a neck pocket, cut the tenon etc.


Fretboard has been glued to the neck, which I like to do whilst it's flat., so today I added the radius and made sure we still had plenty of depth on the fret slots.

I have just added the binding, which is strips of walnut with black purling underneath.

I'm switching to hot hide glue for some stuff.  I haven't really used it much in my builds before, just on restoration  work.  Worked really well for wooden binding and a purfling strip... its a 3 handed job

WezV

Neck






Body.  Pretty much ready for the back to be attached

 
Mockup

SteveRobinson

Those f-holes do look very elegant

WezV

I'm leaning a different way on this build, so might not use the pickup above.

I like the idea of spraying the top gloss black and leaving the rest natural to show the fancier woods, so it's probably going to look a little more modern than the original plan.

Still want to build something around that pickup, but i have other ideas there.

vanlooy1

A Charlie Christian would look pretty cool in that!

davros

Blacktop would look lovely on this but I agree the pickup wouldn't suit a more modern vibe. Those f holes, like on Paulette are super tasteful!

longjaw

Beautiful guitar but that pick-up looks too big and clumsy for such a traditional looking instrument to me - agree that a Charlie Christian one would be much more appropriate.

WezV

the problem with a CC type is the mounting.   Might need a ring and end up a similar size to the PAB pickup.  Although Mojo's P-90 size CC type is rather pretty and would definitely look classy on a black top 

longjaw

Yup - that looks perfect to me!

Andyjr1515

What made you move to starting hot hide glue, @WezV ; ?

WezV

Andyjr1515 said:

What made you move to starting hot hide glue, @WezV ; ?

I'm not totally sure.   I don't believe it makes much of a tonal difference, but I have always enjoyed working with it for the small amounts I have used before.

But I do think its going to work better with the wooden bindings here.   

Firstly, ease of cleanup.  If I was using titebond i wouldn't be able to clean up whilst its got tape on, and there would inevitably be some heavy scraping back to get rid of the dried glue afterwards.  previous attempts with superglue on wood binding have been frustrating to say the least, the risk of white marks is too high.   

Secondly, I can iron them in place if I get any areas I need to fix

just doing the straight bits of neck binding, hide glue made it easier to do the walnut binding and black purfling at the same time as everything pulls together.   I will be doing 3 strips at a time with the body

WezV

back is on and trimmed

Andyjr1515

Looking good, @WezV ;

Ref the hide glue, bindings and ironing gaps, actually that's how I fix bindings nowadays in the first place...but with PVA.

I do it the same way as doing veneer - thin coat on both sides, let it dry, then iron it on.  Like you, I never really got on with superglue and if there was a gap, you were stuffed.  The titebond, glass reinforced tape and cycle-inner-tube binding was messy and time consuming and - however well I tried - there were always gaps when I unbound it 24 hours later.  

Ironing on, I can do a whole side in around 40 minutes total (including the glue dry time) and I know instantly whether it's right and properly seated as I go round.

But - I've never tried hide glue.  Hmmm...might experiment and see what its like.  

WezV

I got myself an old cast iron glue pot of ebay. Although I've also picked up a load of glue bottle/syringes.  So I have boiling water in the main pot, then warm water in the inner pot, and a glue bottle sat in that.  Still playing with ideal temperatures, but its quite forgiving.      I can just mix up the amount I need in a small glue bottle so very little waste

My grandad  just used an old bean tin suspending in a saucepan of boiling water... although his always smelled rancid so I don't think he changed it often... 


Anyway.  I got to use my binding channel cutting jig properly today, and it worked great


But I also realised a mistake with the binding.  

I'm doing walnut, with a single black stripe below and a single black stripe on the inside, which will be done with dyed sycamore veneer.

I bent the walnut strips a while back.   I should have glued the black veneer onto them and bent them altogether.. 

No bother though, just means I need to do things a little differently.   First stop will be to rebend the walnut strips with the black inner layer.   I need to correct them slightly anyway due to spring back.

The strip underneath is more difficult, but once the album it at its final shape I will glue the curved strips directly to a sheet of the black veneer, then trim back.   It's a bit arse about tit, but gets us to the same place.

I also have some areas in the cutaway where the top and back wood would peep under the binding.   I like this on a normal les paul, but not sure it will look right here.   If not, I will blacken it so it matches the veneer 

WezV

Today's job is to get all the binding installed on the body.

So in preparation I made up a bottle of hot hide glue last night. (The bottles get hot to touch!!)

I start by adding the glue directly to the bottle I want to use

Top up just above the glue with water


And wait an hour or so until it becomes one solid gelatinous mass

The glue gets cooked off the night before.   Debatable whether it's needed or not but I do it anyway.   Apparently it creates a stronger bond, but I think the glue I get same day would probably be fine for binding.

This is my setup 


I start with boiling water in the bottom.   Tap water in the inner boiler, and the glue in its bottle.   I bring it up to about 74oC on the thermometer.   The glue will be slightly cooler.   Stays like that for a bit.  Then turned off ready for use the next day.   

I'm aiming for a glue temp of 65-70oC.   Apparently too long about 80oC will kill it off, but it is forgiving to these things.  I keep thinking about getting a hotplate so I can maintain temperature easier, but this is working for me at the moment.


The important bit is that it's proteins arrange themselves in such a way that it starts to form long chains.   You can check this by rubbing between your fingers as it cools. 

WezV

So onto binding.

First job is to add a black strip under the pre bent binding.... this is a pretty wasteful way of doing it.  I am putting some hide glue onto the bottom of the binding and pushing it straight onto veneer sheet.  No need to clamp a join like this with hide glue. Just push it down well.


And I will trim all those back shortly


I've also bound the cavity cover to match


And that has now been gluedand is in clamps


 Note the splice join on the outer strip. 

WezV

And binding is on.


Both top and back had a coat of sealer before hand as this tape can pull wood fibres


I've also left the plates thicker near the edge for now, they will be taken down to the top of the binding in the next steps.  It will stay in tape a day or two  them I will take it off and assess if I have any corrections to make

So we can have messy tap shots for now





But you can see a peek of how it's going to work out