Bindings, Purf's and CA glue

[kencierp]

There is a commercial CA de-bonder -- I've used Acetone to loosen CA joints (now minus many brain cells) it breaks down CA in a flash, my guess is that the commercial stuff is really Acetone.

[Ken C]

Saturday afternoon and evening I bound a claro walnut J-185 with curly maple, BW side and bottom purfs, and herringbone top purf/inlay. CA works so slick as all the pieces can be dry fit, taped in place, and once properly positioned, glued in. Once in, I took my wife to dinner, then came home and cleaned up the bindings with a scraper and sanding block.

Ken

[deadedith]

Ken C - would you take a look at the attached file and let me know if I have the procedure correct?
Thanks
DaveB

[Kevin Sjostrand]

Yeah, I used CA on the back binding/purfling on the Coco guitar cause I was afraid of the AR glue not holding well enough, however I used AR on the top since I was gluing mostly Spruce to mahogany. I liked it.

Kevin

[Ken C]

Ken C - would you take a look at the attached file and let me know if I have the procedure correct?
Thanks
DaveB

Dave,

Pretty much that easy. You only need to seal the edges of the soundboard, don't worry about the back. I typically don't have my purflings pre-glued to my bindings, so I dry assemble everything. I have a procedure I follow that works pretty well. I'm sure others vary their approach slightly.

I route my binding channels then the cavity for my end graft. Some like to install the end graft first then route the binding channels, but doing it in the order I do allows me to really dial in the miters around the end graft. Prior to installing bindings, I install the end graft with the edge purflings mitered and ready to be joined to the rim purflings. The end graft purflings and side purflings are all mitered and dry fit to make sure the joints are good. Once happy, I glue the tail graft purflings in place. Actually what I do is make the end graft wedge a little long then use it as a wedge to hold the purfling in place. I miter to the purfling, hold it place with the end graft, then check the length--removing as needed to adjust the purfling length. Once one end graft purfling is perfect, I'll use the end graft wedge to hold the purfling in place, tacking with several extremely small drops of thin CA along the rim side of the purfling. I then hit it with accelerator to hold it in place. I don't put enough CA in to wick under the purfling and bond the end graft wedge as I want to remove the end graft wedge, so I can work on the other end graft purfling. I only want to tack the purfling in place, and using the end graft wedge ensures the purfling is tight against the rim as I tack it in place. Once one end graft purfling is in, I remove the wedge and work on the other side, tacking it in the same way. At this point the end graft purflings are in and mitered. I have also mitered the purflings that will go around the rim and join at the end graft. I remove the wedge, and cut it to the correct length, checking the length by holding the rim purflings in place and placing some binding material in the channel. Getting the end graft length correct can be tricky, but with patience and a lot of dry fitting, it can be dialed in perfectly. Once happy with the end graft, I tack it in place with a few drops of CA near the center of the wedge. I don't want any CA working its way up into the binding channels yet. Now I'm ready for bindings.

I typically install the back bindings first. Using a very small amount of CA, I tack the side purfling miters on the back side of the rim in place using a scrap piece of binding to hold the purfling in place along the rim. I put on the smallest amount of CA and set with accellerator. I only want to glue the miter, I don't want to glue the purfling to the rim nor glue the scrap piece of binding to purfling or the rim. If you are not careful, you can have CA run along the purfling and cure, preventing your binding from snugging up tight or holding your purfling away from the rims. Once that miter is tacked, I work on the binding butt joint and back purfling joint, using no glue, but making sure ends join tightly. When the fit is perfect, I tape everything in place, using tape every inch or so or where needed. At this point, both back bindings, side purflings, and the back purflings are taped on. I check the joints along the rim for gaps and retape as needed. If there are small gaps visible from the front or the back, I check to make sure any gaps can be closed either by hand or with a little focused effort from the back of screwdriver handle. When I am happy with the fit, I work my way from the end graft to the neck end, push the binding up snug towards the back as I wick in CA from the narrow edge as you show in your picture. CA can travel several inches along the rim, so if you have a gap a couple of inches away from where you are working, be careful or you could get CA in there and fix that gap in place. You can use accellerator, but be careful not to use it if you have a bunch of CA on the surface as it could turn a milky white. Once that edge is glued, I wick in CA from the rim side. Then after I am sure the CA is cured, I'll remove tape and wick CA in all seams again all the way around the perimeter. The same process is repeated for the top bindings.

The process goes fairly quickly, and what I like about CA is that you have no surprises when removing the tape or scraping away glue squeezeout. You see clearly the gaps as you wick in CA. If you do a good job dry fitting, there is no reason you should have major gaps when you are done.

Good luck!

Ken

[deadedith]

KenC - thanks for the clear and detailed advice!
DaveB

[Doublearon77]

Are you using thin CA glue??

Thanks

[Ken C]

Are you using thin CA glue??

Thanks

Yes, fresh, thin good quality CA.