Fretboard / bridge glue down

Another newbie bone head question:
When building with a bolt on neck and a string through bridge, can the finish on the box be left on under the area under the bridge and fingerboard extension ?

Quick answer: No

I consider that bare wood to wood gluing is mandatory for the bridge, even for screw-downs.
For bolt-on necks, some builders glue, others do not. I like to put a fine bead around the perimeter of the neck joint and FB tongue as insurance against twisting and buzzing. If you want to persist with a completely glue-less neck and FB join (readily removable), you should consider using two finer guage neck screws instead of a single.
This method keeps the gap tight and sightly. I have settled on two screws into an implanted hardwood (Tasmanian Oak) heel dowel for larger sized bodies. Providing that the screw holes are drilled to the right diameter, this is a very secure method. I still sparingly glue the perimeters with this method.

I'm happy to glue the fingerboard extension to finish. On a uke, the main reason is to prevent buzzing if the inevitable gap (perhaps invisible, but still unglued) is just the right size to buzz on particular frequencies. It'll stick well enough for that.

But I'd never glue a bridge onto finish. The tension of the strings is still trying to topple the bridge forward, even if it is strung-through. And the string tension also domes up the top, which therefore tries to peel away from the bridge. So I want a good glue joint, which therefore must be wood-to-wood.

To expand a bit on my short answer: Yes, the fretboard "tongue" probably could be glued to finished woods since it is really not holding the neck in place. However, the bridge is a different story and I agree with the above answers. The OP never said what type of finish was applied which is sort of important. If it was an oiled finish there really isn't much you can do at this point since the finish has soaked deeply into the wood. If it is a shellac, nitro, poly finish, etc. there are things you can do:

Find the proper placement of the bridge. Put masking tape around the bridge. Remove bridge and scribe a line 1/16 of an inch inside all around the tape edges. Remove finish with razor blade/scraper whatever until bare wood is reached. This will create a slight (depending the depth of the finish material) rim around the bare wood. In my experience this has not been a problem, however some prefer to use a router right to the edge which takes skill. Glue bridge on as usual and next time mask off that area before finishing.

I have always scraped away a shellac or shellac/Truoil finish at the bridge. I have always masked off the bridge location on a lacquer or Tru oil only soundboard finish.

I don't normally pore fill but recently have done so on the back and sides only using either CA or Z-poxy. To expand the original question, what do makers do if they pore fill the soundboard?

Would you ever glue a bridge to a soundboard with a continuous pore fill coating or would you ensure there was wood to wood contact at the bridge? I say 'continuous' because I know some sand back so that only the pores are filled whilst others will apply a final continuous wash coat of the filling medium ( CA, Z-Poxy etc) before applying the finish. The implication here is that the bridge location may need to be masked before any pore filling is commenced. Is this so?

I hope I have adequately put the question.

I mask both the fingerboard tongue and bridge location with brown parcel tape, which then stays in place throughout the epoxy pore filling and finishing process. Epoxy and finish are applied over the tape. The tape is first cut to size in-situ using a new scalpel blade to cut around the bridge & fingerboard using them as templates. After finishing, I pop the bridge back in place and temporarily fit the neck before repeating the scribing process with another new scalpel blade.The tape is then carefully removed and if necessary any adhesive residue cleaned off with appropriate solvent. I then have a perfectly outlined bare wood surface to glue to with no need to scrape back any finish. The reason for using parcel tape rather than conventional masking tape is that it is so thin there is no meniscus build up around the edges, and it can freely be sanded straight over without damage. The only downside is it can be a pain to remove as it tends to come off in small pieces.

greenscoe said:

I have always scraped away a shellac or shellac/Truoil finish at the bridge. I have always masked off the bridge location on a lacquer or Tru oil only soundboard finish.

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Not sure I understand what you saying. If you masked off the bridge location, why would you need to scrape away any shellac/Truoil? There shouldn't be any there...

As for masking prior to pore filling on a soundboard? Yes, you need to mask as you want bare wood to glue to. I assume you are talking hardwood soundboards because spruce does not need to be filled.

Thanks for the replies. Getting frustrated with figuring out how to use this message board. So gluing the fretboard tongue without removing finish appears to be ok. The original bridge idea is scrubbed. On to the next bridge ider. Making the bridge movable, without using a tailpiece. The ider is to locate string holes near the tail block since the top has a skin brace. Any takers? Thanks again.

Wildestcat said:

I mask both the fingerboard tongue and bridge location with brown parcel tape, which then stays in place throughout the epoxy pore filling and finishing process. Epoxy and finish are applied over the tape. The tape is first cut to size in-situ using a new scalpel blade to cut around the bridge & fingerboard using them as templates. After finishing, I pop the bridge back in place and temporarily fit the neck before repeating the scribing process with another new scalpel blade.The tape is then carefully removed and if necessary any adhesive residue cleaned off with appropriate solvent. I then have a perfectly outlined bare wood surface to glue to with no need to scrape back any finish. The reason for using parcel tape rather than conventional masking tape is that it is so thin there is no meniscus build up around the edges, and it can freely be sanded straight over without damage. The only downside is it can be a pain to remove as it tends to come off in small pieces.

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Thanks for that Paul. You have confirmed what I thought was the case. I know what you mean about that parcel tape it can be a pain to remove.

Where have you been recently? Hope you are still making guitars and ukes.

sequoia said:

Not sure I understand what you saying. If you masked off the bridge location, why would you need to scrape away any shellac/Truoil? There shouldn't be any there..
.

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I don't mask if I use shellac or shellac with a Tru oil top coat. In these cases its easy to scrape.

greenscoe said:

Where have you been recently? Hope you are still making guitars and ukes.

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Yes, still building ukes though I haven't done a guitar for a couple of years now. I have a Facebook page where I post updates and the occasional video https://www.facebook.com/pg/Wildcat-Ukulele-244589976311353/posts/?ref=page_internal