Fitting a maple cap

axisus

This seems like a dumb question: if you are fitting a 2 piece maple cap, would you glue the two pieces together first?

TTony

Yes.

octatonic

Yup, definitely.

WezV

there are a few occasions where you might consider doing it the other way, but you will never get a really clean join line

I have only done it where the top has been unstable and bowed enough to make it hard to fit together - but its better to avoid wood like that than attempt to join on the body

clamps can be a bit much on thinner tops, you need a plate joining jig of some kind

octatonic

WezV said:

clamps can be a bit much on thinner tops, you need a plate joining jig of some kind

I just use two pieces of MDF slightly under the width of the piece that you are joining and then use some panel clamps.
I put some barbell weights on top of it to exert some downward force.
I do this with acoustic guitar tops and backs as well.

I'll see if I can dig out a photo.

WezV

there you go, there is your joining jig - no need to be fancy

octatonic

WezV said:

there you go, there is your joining jig - no need to be fancy

It was how we were shown at uni- very simple but very effective.

axisus

octatonic said:

WezV said:

clamps can be a bit much on thinner tops, you need a plate joining jig of some kind

I just use two pieces of MDF slightly under the width of the piece that you are joining and then use some panel clamps.
I put some barbell weights on top of it to exert some downward force.
I do this with acoustic guitar tops and backs as well.

I'll see if I can dig out a photo.

It would be great if you have a picture!

paulnb57

Imagine the two pieces of MDF mentioned above are arranged like an = the gap between the two pieces is just slightly less than the width of the two pieces you want to join. You glue the join an put the two pieces between the = they dont quite fit flat as the = just a bit too close together, but add weight and it forces them in, exerting pressure on the join...

octatonic

And don't forget some newspaper along the join on both sides- you don't want to glue the mdf to the wood you are joining.
You can scrape the newspaper off easily with a Stanley blade.

octatonic

Apologies but I don't have many clear pictures of this process other than this:

AustrianJohn

You can also use a piece of wood clamped to the top instead of weights. You can also rout a channel below the glue line so you don't stick the top to your jig.

axisus

Thanks all, useful stuff for current guitar build

Kalimna

Instead of using newspaper under the glue line which then has to be scraped off, i use tbe wrapper that comes with Warburtons loaves. Sounds daft, but its free (after the bread is eaten of course) and it has an almost wax-paper quality that seems impervious to PVA, aliphatic resin glue used in luthiery.

Another plate-joining 'jig' is to use a series of panel pins alongside the outer long edges of the plate to be joined. You hammer in the pins whilst the plates are held together on a baseboard with a removable support (say 7-10mm high and 20mm wide running the length of the glue line) underneath the glue line. When the support is removed and the plates weighted down, the wedge action provides plenty of clamping force for the join. Much harder to describe than show, adaptable to any shape of plate that would otherwise be difficult to accurately clamp, cheap and low tech. I may have a photo somewhere i can post up.

Adam.

P.s. if you are near Stirling at all, i would be happy to show you.