Joining Pieces for Top and Back

I've seen a technique online for joining the two halves of the top and side. Lay the pieces side by side and run a piece of tape down the joint to hold them together. Fold them together and stand them up and apply glue to the joint.

My question is, does the tape go on the good side or the side that will be inside the uke? The videos I've seen are high speed, with no commentary.

Sounds like the “tent” method...I’m not an expert on that one.

It does not matter. You may get some glue squeeze out to clean up on the tape side.

I'm not sure of purpose of the tape, to join or to keep one side clean, either way it is not the complete way to join halves. For joining and gluing you need to apply lateral pressure pressing the joint together to make it tight and hopefully invisible. As far as keeping it clean, you can put the show side up when gluing and wipe off the excess glue after joining. I also use a cabinet scraper to remove the glue residue when dry or firmly set. Depending on the type of wood and type of tape, the tape can also pull up wood fibers while removing the tape which does more damage than good in that case.

Kelali Kev said:

I'm not sure of purpose of the tape, to join or to keep one side clean, either way it is not the complete way to join halves. For joining and gluing you need to apply lateral pressure pressing the joint together to make it tight and hopefully invisible. As far as keeping it clean, you can put the show side up when gluing and wipe off the excess glue after joining. I also use a cabinet scraper to remove the glue residue when dry or firmly set. Depending on the type of wood and type of tape, the tape can also pull up wood fibers while removing the tape which does more damage than good in that case.

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Just guessing, but I think the purpose of the tape is to keep the pieces together so they can be "tented," as Timbuck mentioned, and also to keep the glue from bleeding through. The videos I've seen have also used pressure from the sides to hold them together. They used blue painter's tape for easy removal, and this was before any sanding or finishing.

I thought it was odd that one guy used two pieces of wood for each side piece, so the sides were double-thick.

Here's one using the tenting - https://www.youtube.com/watch?v=6O41Ar9sAJs&t=1128s

And a real beauty - https://www.youtube.com/watch?v=CdT6C4sn9pI

Reply from one of the builders -

"I can't really remember but it doesn't really matter as I'm scraping both sides afterwards. It's not for clamping purposes it's just more practical when the 2 thin pieces of mahogany don't fly around the shop as I'm gluing them for the clamping, the mdf stripes do all the job. I don't show it in the video but there's a method for good clamping pressure : just put a 2-3 mm thick material (I used a ruler) underneath the gluing area, and clamp your "fences" to the workbench in that position. It gives consistent clamping pressure along the whole joint area. Some people also use lateral wedges but these boards are very very thin (1,75 mm). Hope I answered the question and thanks for watching!"

This is the method I use to join the two top plates and it works perfectly - no elaborate clamping jigs required. The plate are folded (after sanding the edges of course) at a 45 degree angle, tape is applied and stretched (using a stretchy type auto tape). When the plates are then laid flat the tape pulls the two pieces together very tightly, clean up the excess squeeze out and put a weight on the joined plates and let dry over night. I get perfect joins with no visible seam whatsoever. In effect the tape acts as a clamp. Simple and effective.

As Ken said it is called the tent method and the purpose of the tape is to supply some clamping pressure to the joint. It is best used when you are using HHG, Rick Turner is a big advocate of this method. To preserve the accuracy of the book matching, the tape is applied to the back of the joint, with the edges held together at an angle. The big advantage of this is after the pieces have been taped, it only takes a couple of seconds to apply the glue and clamp them flat, very important with the limited open time of HHG.
Brad

I've used the tent method, quite like It. If you are using a glue that dries through evaporation e.g. titebond there is another way. Although your brain will tell you it doesn't work, it does, but you have to get your joint perfect. Lay them down flat next to each other with wax paper underneath. Leave a small gap between the two halves. Apply a bead of glue along the edge of one side so it trickles into the gap. Push together and slide back and forth an inch or so. Leave them. No weights, no clamps. As the water in the glue evaporates it pulls them right together. If you are left with a gap, you didn't get them planed true in the first place.

Essentially glueing without stress. If you have to force the joint together, it will forever more be trying to separate. Ever wondered why so many tops split at the joint?

Right I will sit back and wait for the onslaught

I've only ever used the tape tent method and have built over 500 instruments. It works with either HHG or Titebond type glues.

It's fast and easy with no need for any other equipment.

Allen said:

I've only ever used the tape tent method and have built over 500 instruments. It works with either HHG or Titebond type glues.

It's fast and easy with no need for any other equipment.

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What is HHG?

You think planing is the best way to get a perfectly flat edge?

I glues the pieces together with clamped boards applying pressure from the side and weights on top. So far, so good.

HHG= Hot hide glue. Good stuff.

Planing- see Robbie O'Brien's video on the LMI youtube channel on using a shooting board to joint.

hoji said:

HHG= Hot hide glue. Good stuff.

Planing- see Robbie O'Brien's video on the LMI youtube channel on using a shooting board to joint.

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I don't mean to be funny, but does that mean hide glue that is heated? I do have some hide glue.

Jerryc41 said:

I don't mean to be funny, but does that mean hide glue that is heated? I do have some hide glue.

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Yes, roughly 140 F.

If you're interested in HHG, I think the info from Frank Ford on frets.com is arguably the authoritative source on how to use it for luthiery.

Edit- lots of masters use titebond, too. I just find a certain fun in the hhg process. (and I'm far from mastery).

Red Cliff said:

I've used the tent method, quite like It. If you are using a glue that dries through evaporation e.g. titebond there is another way. Although your brain will tell you it doesn't work, it does, but you have to get your joint perfect. Lay them down flat next to each other with wax paper underneath. Leave a small gap between the two halves. Apply a bead of glue along the edge of one side so it trickles into the gap. Push together and slide back and forth an inch or so. Leave them. No weights, no clamps. As the water in the glue evaporates it pulls them right together. If you are left with a gap, you didn't get them planed true in the first place.

Essentially glueing without stress. If you have to force the joint together, it will forever more be trying to separate. Ever wondered why so many tops split at the joint?

Right I will sit back and wait for the onslaught

Click to expand...

I use the rub method to glue bridges on ukes since I have no clamps that reach through the soundhole. There is really no room to rub since the bridge sits so nicely into the clean spot in the finish, but fore and aft pressure until the glue grabs works fine. Since my tops have the slightest dome I clamp a flat board near the bridge area to press out the dome temporarily.

I always use the tape method to glue plates together, but I don't see why the rub method wouldn't work. The advantage of the tape is that I can immediately pick up the glued plate and move it out of the way. I often join a dozen plates (or more) at a time and I always seem to work on the deck of my table saw, so stacking the glued plates out of the way is the way to go. Jointing and gluing plates is big fun.