Quote:
Originally Posted by Twilo123
2. i also glued the braces to the back (pic 2). the back braces were noted not to clamp to anything flat as it is curved. i put the flat edge of the braces lined up against a ruler and noticed that the braces themselves were indeed curved. is this normal in guitar world also? are the back braces supposed to be cut/edged curved and have something of a bowed back?
3. i am concerned about my glue job...as you can see in (pic 3) there is some space between back/side even though i am clamping them. quite possibly the sides were not level enough and as a result there is some space when gluing. does wood glue expand to fill gaps? my understanding is wood glue looks to attract to wood instead of fill gaps like say epoxy would. if when the wood is dry not all points have contact do i need to somehow pull the top off, re-sand until more level, and re-glue again? or could i patch with some epoxy or something for the part that is not fully stuck together?
4. also i know for some glues you should rough up the surfaces to be connected for there to be good contact. is this the same for this wood? for instance i roughed up the bottom of the braces with a blade so hoping it would help them adhere better to the back/sides. was this ok to do this or a bad idea?
5. gluing question: rather than wiping glue on wood all the time with my fingers how does everyone apply glue to various wood surfaces? i thought i saw a video of someone using a paint roller to apply glue to wood so i bought one. i figured the regular paint rollers are too soft and pieces would pull off with the glue so i found 1 that uses a harder plastic roller (pic 4) however upon trying to use it i found it was pulling off the glue as much as evenly spreading it out. i could not find any metal based roller end so i am not sure how people are using rollers or how they are applying glue other than finger/hand. maybe a brush? need something reusable though. any suggestions?
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Backs (and tops) are curved to act as expansion joints so your instrument doesn't crack as it expands/contracts over RH gains/losses. As the RH rises, so should the curvature of the back and top. Reverse for falling RH.
The best glue joint is wood-to-wood. Anything less and there are more chances for trouble. This instrument won't be pulling quite as much stress on the top/back joints with sides compared to a guitar, so you have more room for error. But...
I use my finger to spread glue. When I asked my guitar building master how to get the amount of glue right, he said, "Just put the right amount of glue on!" 'Nuff said! ;-) You can smooth it with a finger and wipe the excess from your finger on the edge of a garbage can.
Certain glue joints are best NOT roughing with sandpaper or whatever. For example, centre seams in top and back should be planed then glued immediately. Braces...??? Hmmm.... Different people likely have different ideas. I've done both (sandpaper preparation and plane preparation). I think the most important thing is a consistent curvature along the length and flat surface along the width.