Top first or back first?

[watergunn]

I am on my fourth build and have always glued the top on before gluing the back on.

Does it really matter which one is glued up first?

Is there a preferred way?

Just curious.

Thanks

[tippie53]

I do the back for 2 reasons , 1st is that you see the back from the sound hole and it is easier to clean the glue off the back with the top off. also using a concave dish helps to keep the body from being racked.

[watergunn]

Makes sense.

Thanks John.

[Ben-Had]

There are those (not me but I've tried it) that glue the top on first so they can fine tune the voicing. If the back is on you can't get to the braces to do that. Don't know that my ear is good enough to tell the difference so I go back first to clean it up.

[Kevin Sjostrand]

I have also always glued the back on first so I can clean up any visible glue. I don't know that I would know what I was doing to try and shave braces after the top was on anyway. This has worked for me so far.

Kevin

[Ken Hundley]

I have always glued the top on first. No particular reason. It's worked so far, and I have never worked the braces after the plate has been glued to the rim.

[deadedith]

I like doing the top first for the reason stated above - it provides access to voicing the braces for the last time before the box is closed up.
My reasoning (which is always suspect :-)) is - I braced and tuned the soundboard as best I could, but then gluing it to the rims creates a new entity - top+rims, so now I need to tune that entity as well, which I can do by paying close attention to tapping. It's not difficult.
As for glue run-out when gluing on the back, I think I saw in one of Somogyi's books that he glues on the back and then flips the whole thing over so that the glue does not have a chance to run.
$.02

[Darryl Young]

I go back first to clean up gllllue easier. Also, the back is arched more than the top.......so I lay the back in a dish with the correct radius, place the rim on top, then put 2 or 3 go-bars in the middle portion of the back to make sure the back is against the dish where it has the desired radius, then I place go-bars on the top of the rim to push the rim down against the back.

The top will change the way it vibrates once it is glued to the rim. However, it will change again when the back is glued in place. The resonant air frequency will affect the frequency of the vibration modes. Also, if the back is not rigid and tuned somwhere resonably close to the top, the back plate couples with the top which will affect the frequency of the vibration modes. So if you do your final tuning before the back is on, things will change after the back is glued in place.

[tippie53]

I have after 150 guitars dialed in my top process and will do a little tweaking once they are strung up. In a nutshell I don't think this is all that important as long as you are comfortable with what you are doing.

[deadedith]

Darryl - here's a way around the difficulty you pointed out in my method.
Glue the top on, then tape -securely- the back on and do your testing. Tests by Brian Burns have shown that taping on the back - everything having been done properly - gives the same results as gluing it on as far as resonance testing goes.
So, that gives the sequence: tap your top, adjust; glue the top on, adjust; tape on the back, test, and if adjustment is needed, un-tape the back, adjust, re-tape and adjust, then glue it on.

The process gives you ample opportunity to tune the box at various stages, which I believe is a huge benefit.
$.04