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| Bolt on/dovetail glue downs http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=25932 |
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| Author: | Bailey [ Sun Feb 07, 2010 1:23 pm ] |
| Post subject: | Bolt on/dovetail glue downs |
Gang of mighty luthiers, I am nearing the duty of attaching the necks on 2 steel string (000 and OM) projects. One dovetail and the other a bolt on. I did NOT tape off the area before finishing where the fretboard meets the top on both bodies. Am I going to need to scrape down that finished area before gluing down the neck/fretboard the the top.?....or will the LMI luthier glue work well enough on a lacquer finish to do the job. Not a great bond...but.... Maybe a different glue? I assume, since the fretboard-to-top area is not as critical to strength and support as the heel joint itself...it wouldn't need that raw wood to wood glue prep work. Wrong? I am also a little leary of my dovetail fit.... It seems to have just a (ever so slight) pull way at the tip of the heel. If I push HARD and hold the neck all the way down into position, it doesn't move...but as soon as I release tension downward in it's position, it seems to rise a bit and then the heel end moves away a bit. Maybe the glue in the dovetail joint and soundboard/fret area will be sufficient to hold everything in place. I was actually thinking about setting a bolt through the block into the mid section heel just in case my final glue up doesn't hold under string tension. Anyone ever done a bolt on dovetail? Always making things complicated. Kent |
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| Author: | Laurent Brondel [ Sun Feb 07, 2010 1:46 pm ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
Kent, you will need to remove the finish under the FB extension. The way I do it is to tape (blue masking tape) around the FB extension when the neck is on, remove the neck and cut through the finish with a 6" ruler an x-acto knife (you need a brand new blade that tracks well), leaving about 1/16" of finish around the edges. Then lift the finish with a sharp chisel and scrape, or sand lightly with a small block, until bare wood is exposed. Wood glues will not adhere to finishes, not well enough anyway. For the dovetail it is not unusual to have to shim them (glue a piece of mahogany veneer on one side of the neck dovetail, or both), and rework the fit, so there's no shame in that. Chalk or carbon paper are your best friends. I think Sergei DeJonge uses one bolt with his dovetails. |
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| Author: | bluescreek [ Sun Feb 07, 2010 4:05 pm ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
Todd is 100% correct , you don't bolt a dovetail unless you want problems . Laurent has given solid advice also on getting the finish off. The only thing I do different is I use safety razor blades to scribe and scrape . Same church different pew. |
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| Author: | Barry Daniels [ Mon Feb 08, 2010 9:56 am ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
Might want to reconsider the blue masking tape too. That stuff will damage new finishes pretty quickly. |
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| Author: | Rene [ Mon Feb 08, 2010 10:08 am ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
Barry, tell more about the blue masking tape damaging the finish, I thought it was universal for what we are doing. How do you do it? René |
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| Author: | bluescreek [ Mon Feb 08, 2010 10:27 am ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
I have used the blue tape without issues for years. One thing you need to do , is be aware of the grain direction. Any tape if pulled off against the grain can lift the wood fibers. |
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| Author: | Bailey [ Mon Feb 08, 2010 11:12 am ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
Well that probably explains why my dovetail doesn't seat like it did before finish. I have 6 coats of lacquer under the fretboard. I take in info. from multiple sources and 2 sources DO apply finish to the entire body and didn't mention taping the fret area.....and even mention leaving the neck slightly proud of the body to allow for finish. So......what's a guy to do. Thanks for the replies. Gluing to a finished surface (even roughed a bit) just didn't seem right. It'll be a scraping finish morning. Kent |
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| Author: | bluescreek [ Mon Feb 08, 2010 1:24 pm ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
I use blue painters masking tape from lowes and the green tape from 3m at uline. I use them both for masking and binding . Some tapes are not lacquer friendly as Todd points out . When I am masking off lacquer to rout out the bridge area , I use the tan masking tape only. |
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| Author: | woody b [ Mon Feb 08, 2010 6:04 pm ] |
| Post subject: | Re: Bolt on/dovetail glue downs |
I use the 3M green (233+) If I'm afraid of it's strong tack I stick it to my pants leg and remove it before sticking it to the wood. This makes it a little less sticky. |
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