Official Luthiers Forum!

Once again I ended up with a visible seam on the top.
I made a very good joint and glued the seam with epoxy using a good amount of clamping pressure.
I glued the top to the body using Titebond.
I suspect the Titebond swelled the wood and then the wood shrunk while drying.
Any suggestions for the next one?
I thought of using a slow set epoxy rather than a water based glue.
I'll leave this one as-is, I think any attempt to cover it will not look good.
Thanks,
Dan

_________________
wah
Wah-wah-wah-wah
Wah

Had a friend with the same problem. His was caused by a dirty plane sole which didn't look at all dirty. Cleaning it with lacquer thinner revealed the problem. Hope your issue is as easy to solve.

Steve

I suspect your joint was not as nice as you thought. It appears to be fairly tight at the ends with more of a gap in the middle. This was not caused by either of the glues simply looks like a joint that could have been fit better.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

The only upside is, some of the joint will be hidden under the neck ,bridge, pups, strings and a pick guard, if you use one. It looks like the joint is ok behind the bridge.

_________________
http://www.cushmanguitars.com/.

A man who carries a cat by the tail learns something he can learn in no other way.
Mark Twain

Yeah,
It should look fine.

_________________
wah
Wah-wah-wah-wah
Wah

I've always had trouble "shooting" that joint so the last few I've simply clamped the two pieces together and clamped a very straight piece of aluminum flat stock to them (you could use a straight level). I've just run the router with a flush cut bit and the joints have been darn near perfect. You might want to practice on some scrap but at least for now that's the way I'll be doing it.

Good idea!
Thanks Freeman.
Dan

_________________
wah
Wah-wah-wah-wah
Wah

I'm assuming the maple top is around 3/8" when I say that it is a lot harder to make a good joint than with a 3/16" top. Archtop guitars and mandolins are even worse with 3/4-7/8" thick tops and backs.

OOPS, DOUBLE POST!

The seam is definately a poor joint.
I have a good technical knowledge of guitar making, but my woodworking skills are not so great.
I'm trying to use mainly hand cutting tools, but I need to rethink and use whatever tools will produce the best results.
Thanks for the feedback, you fellows are the best!
Dan

_________________
wah
Wah-wah-wah-wah
Wah

Seams sometimes are hard to come by. Nice ones anyway. Practice helps


Sent from my iPhone using Tapatalk

I use sandpaper glued to an aluminum straightedge,1" x 2",
put a 1/4" piece of something under the top,
and carefully sand away,
checking the joint with light behind it.
The sun works well for the light source!
After you put all the pickups, bridge, and whatever else,
nobody but you, or another luthier will notice.
Alan

Did you use a shooting board? If so, and you want to continue to use this method, shoot them together, one on top of the other with the top of each facing inward. A slight angle will show up as a visible glue line if you do them separate, but if you do it this way any angles created will be supplementary angles, so you'll get a nice joint.

Brian mentioned above it looks like the top and bottom are fine, but the middle is there is a gap. Which should be theoretically impossible with a shooting boards. Some people construct their boards at a angle to the plane, like the link below. This is done so that you aren't just using a small portion of the plane iron, and you have even ware on the plane. If you are shooting, and you are using that style of a board, then it's possible it's cause by plane setup.

Also, I like Freeman's idea. I may give that a shot.
http://www.breseplane.com/olive1.jpg

I do this type of thing all the time...

though I use a top bearing flush cut bit (read as pattern bit) and always climb cut first then go back again traditionally cutting to clean things up...one very big concern is that the router bit must be perfectly square to the base...this problem can be mitigated by doing what has already been suggest...clamp the 2 pieces together (assuming your bit is long enough to trim both at once) in a bookmatched fashion (e.g. to be seen faces touching) as this will result in any angle off of square to be reflexive (read that as when pieces are oriented to be joined and doing so any error will still result in a flat glue up)

Well, I'm pretty sure the gap was caused by humidity changes.
The gap is no longer visible at normal humidity levels.
I'm working on a hollow body and have really noticed wood movement.
I cannot afford to control my garage environment.
We had 30 straight days of rain, then 30 straight days of drought.
Now the humidity levels are around 50%.
This was a good learning experience for me.
Thanks,
Dan

_________________
wah
Wah-wah-wah-wah
Wah

Can I ask why you used epoxy for the bookmatching.

Sent from my SGH-T599 using Tapatalk

_________________
Another day, another dollar.

Michael,
My reasoning was to water-proof the joint.
I applied a water based dye to the top and I was worried about water softening the joint.
Also, if I ended up with a gap, I would be able to sand the epoxy better than I could sand Titebond.
I'm gluing tops with slow-set epoxy these days. I've had veneers and 1/4" tops crack while drying using Titebond, probably because of the wood shrinking, and from applying too much clamping pressure not allowing it to move. Also, the epoxy has a much longer working time to spread out an even coat.

I still use Titebond for everything else.
Dan

_________________
wah
Wah-wah-wah-wah
Wah

Okay I have never experienced problems with titebond on tops. But then again I don't use waterbased dyes. I wouldn't have thought it would have an effect like that.

Sent from my SGH-T599 using Tapatalk

_________________
Another day, another dollar.

I had a problem which *looks* similar when joining an acoustic back with Titebond. After a couple of days the edges of the seam curled up and out slightly, leaving me with small ridges with a dip in between. Unfortunately this was on the face side, which I'd lined up so well that I hadn't had to take it down in any significant way (on the inside I'd removed material to achieve final thickness, and the joint was fine on that side). My guess is that the swelling and shrinking during glueing produced this effect, and if only I'd left the thicknessing another couple of days I could have removed the offending parts. Maybe in your case enough moisture seeped through from the Titebond to produce the same effect? If so, I think the answer is to leave a little extra wood on and then remove it once the joint has fully cured.

If it's a poor-fitting joint, you might try the technique of a friend of mine (though we both make ukes, which are much smaller - this might not work for guitars). He simply clamps his jointer plane upside down in a vice, holds the plates together, and then passes them along the plane. I tried that recently and got a very well-fitting joint with far less effort than normal.

Very true! It will also melt the cells in your macula very efficiently unfortunately. Not a good idea for the long term performance of your eyes even with quality sun specs on!

Epoxy is aggressive and WILL seep into Maple. Maple is actually fairly porous. I use epoxy for everything EXCEPT panel edge gluing on light colored facings. For that I use Tightbond.

Still....I suspect it's the edge joining rather than having used epoxy that is causing your problem.

I use a cnc machine to provide a perfect edge to my plates. I also made a gluing jig that provides a LOT of edge pressure when gluing. This always creates a fantastic seam.

Although it's harder with more conventional tools....I can say with certainty that the better you join those edges...and the more pressure you use when gluing....the better the result.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Dan we see a lot of small Luthier built instruments and when I can see a center seam it's often because the maker used sand paper to refine the joint. The contamination from the abrasives if not totally removed can darken a joint enough to make it show.

Rule one in our shop for repairing cracks to be invisible is to wash our hands because even the dirt on our fingers likes to go on the move once we are poking and prodding with wet glue.

Thanks for the advice fellows.
I bought a Freud rip blade for my table saw.
It is advertised as producing a jointed surface.
I have tried a couple of different woods, and the joints look better than what I have been getting by hand jointing. The surface it leaves is smooth and clean.
On my next top, I'll rip saw the jointed side before I saw the board into two plates.
I'll rig up a proper clamp to apply pressure while gluing.
Dan

_________________
wah
Wah-wah-wah-wah
Wah