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Tape or scrape?
Posted: Wed Mar 02, 2016 9:51 am
by John J
Wondering what the preferred method in regards to the bridge placement prior to finishing. Do you finish and then scrape? If so what are you scraping with? If you tape are you using any particular tape and how are you dealing with the edges of the finish along the masking?
So far I've masked, but just wondered what everybody else is doing and why.
Thanks
John
Re: Tape or scrape?
Posted: Wed Mar 02, 2016 11:56 am
by ken cierp
With either method its important to make sure there is a tiny bevel of around the perimeter of the bridge to help avoid placing the glue surface on the applied finish and degrading the glue joint contact.
As for scrapping off the finish --- if not using a CNC machine for this procedure and even then, to my way of thinking it is totally counter intuitive --- protecting the area and maintaining the pristine surface is far more logical than going back trying to "re-create" a pristine glue surface. Plus the stress and challenge of not damaging the sound board.
For me the choice is very easy.
Re: Tape or scrape?
Posted: Wed Mar 02, 2016 12:53 pm
by John Parchem
I am not saying it can not be done and I have seen many successful examples on this site of people taping the bridge area and gluing on a bevel bridge. Ken's documentation has a good description of how to make and apply the mask. But since the OP asked for reasons why others do not tape ...
I personally have tried but have not successfully taped the bridge area close enough where I could eliminate scraping to the perimeter of the bridge. Worse still I have over taped the bridge leaving a gap between the bridge and the finish.
So I mostly leave the bridge area un-taped, I scribe the finish carefully with a fresh scalpel blade, I use a utility knife blade or a razor blade to scrap out the bulk of the finish and finally use a chisel to knock the last bit of finish off to the scribed line. I am sure there are errors I am making in the taping process, but I have found in nearly every application where I use tape as a masking I fail.
Re: Tape or scrape?
Posted: Wed Mar 02, 2016 2:05 pm
by John J
I had just been browsing and come across a build log where a small "router plane" from Lee Tools was used to scrape the finish off. It looked interesting. Just wanted people's thoughts.
Re: Tape or scrape?
Posted: Wed Mar 02, 2016 2:24 pm
by Jim Ebert
John, do you happen to have a link to the build log using the router plane. I would be interested in seeing it.
Jim
Re: Tape or scrape?
Posted: Wed Mar 02, 2016 2:46 pm
by John J
Jim Ebert wrote:John, do you happen to have a link to the build log using the router plane. I would be interested in seeing it.
Jim
Here you go:
http://www.acousticguitarconstructionfo ... =30&t=108a
Re: Tape or scrape?
Posted: Wed Mar 02, 2016 3:08 pm
by Dave Bagwill
There is a 3rd option - sand. On a few instruments, I have accurately cut the shape of my bridge out of a piece of stiff material, taped the resultant outline onto the guitar and lightly sanded the finish off. It works fine, no downside that I have noticed. Sure, one has to be careful, but that is the case for any of the 'removal' processes.
Now I mainly just tape off the bridge area first and avoid having to sand or scrape.