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fiddlerjer

Tack gluing?

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Pretty soon I am going to be ready to trim the edges of my top and bottom plates and mark the purfling. I want to glue the top and bottom to the rib assembly but I'm not sure what I should do to ensure the glue joint will come apart easily once I'm ready to hollow out the plates. Should the glue be thinner than usual? Do I only put glue on a small portion of the gluing surface?

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Yes, the ribs are on the mold. I have not made any provision for alignment pins, I reckon I could add them. Then I could trim the edges and mark the purfling without gluing up?

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My only experience is to align the plate to the ribs, clamp, drill through the plate into the top and bottom blocks. You can insert drill bits as pins and scribe the outline.

P.s. 

I'm no expert,

Pete

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17 minutes ago, duane88 said:

in slc we tacked the plates on with a dot-a small dot-of white glue for doing the outline and purfling.

Thanks, that sounds workable. Was the dot on one of the blocks? Or rather I guess it would have to be two or more of the blocks. To separate the pieces when you're done, did you just pry them apart with a chisel?

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8 minutes ago, fiddlerjer said:

Thanks, that sounds workable. Was the dot on one of the blocks? Or rather I guess it would have to be two or more of the blocks. To separate the pieces when you're done, did you just pry them apart with a chisel?

I'm gonna take a wild guess and say that each block had a small dot of glue. I would imagine that the plates would be released with a simple opening knife, or small hammer and a block, but Duane can correct me if I'm wrong on this. 

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We put a small dot on the inner most part of the corner blocka and a small dot on the insdie corners of the end blocks. The blocks are still full and when you shape the blocks the spot where you glued will hopefully be carved away. Mike Scoggins used to bitch at me for putting too big of a dot. You do want it to pop off when you want to get it off. He used the tip of a wooden match to place the micro-dot. We left the plates spot glued to the rib structure for much of the work of the outline, purfling and working the arch down with finger planes.

p.s. pop the plates off with your opening knife. If you need a chisel, you used too much glue.

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2 hours ago, fiddlerjer said:

Pretty soon I am going to be ready to trim the edges of my top and bottom plates and mark the purfling. I want to glue the top and bottom to the rib assembly but I'm not sure what I should do to ensure the glue joint will come apart easily once I'm ready to hollow out the plates. Should the glue be thinner than usual? Do I only put glue on a small portion of the gluing surface?

Since the rib is still on the mold,  I would put thin glue on the blocks ,  and only in the place where the wood will eventually be trimmed off.  

To separate the pieces you can use a pallet knife for oil painters.  Pallet knifes are thin and have dull edges.  You insert the pallet knife in between the pieces, sliding along to the glue joint and it will pop open.   In the cases where there is already an open seam, it's much easier and safer to separate the pieces. At least you won't poke into the wood instead of the joint.

I did it several times myself when I wanted to evaluate the edge overhang before purfling . 

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5 hours ago, duane88 said:

We put a small dot on the inner most part of the corner block and a small dot on the ins[ide] corners of the end blocks....

You could do this but add a paper separator at each block -- a glue dot on the block followed by a small piece of paper followed by another glue dot and then the top.

Edit:  Help.  How can I edit to remove the strike-throughs?

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20 minutes ago, Brad Dorsey said:

You could do this but add a paper separator at each block -- a glue dot on the block followed by a small piece of paper followed by another glue dot and then the top.

Edit:  Help.  How can I edit to remove the strike-throughs?

You could, but the rib structure is already flattened on the back and should be near if not the finished height so adding a paper separator would require re-flattening the rib structure. No reason to do that twice.

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Alignment pins are Truth, Fact, Judge and Jury.

No guess work, no doubt, no shadow cast, no run out.

If I'm about to be charged with a crime, guilt is only implied with out the presence of law, the establishment of the standard of righteousness.

With the pins, I start out confidently that this is exactly the right position of the plate, and any stretching and pulling to get the over hang even, is in the right starting place. At times a pin might need to be left out of the final gluing. But it will be close to the pin spot,,, just no cigar.

That way I won't spend a lot of time tugging around, only to find out later, that the entire plate is shifted.

I glue size the plate and ribs, then I let the glue dry and clamp the ribs to the plate.

Then when it looks right I remove a few clamps at a time and glue that section. I move around the entire plate that way.

To not use pins automatically introduces a variable in the methodology that will always be a possible source of inconsistencies.

This becomes more evident as one ages and the workmanship starts to lose it's youthful vigor.

At that point it can take on a relaxed softness, and that can start looking a bit a bit unnecessarily sloppy, but using pins eliminate a certain aspect of that.

Things can be a wee bit out of shape, but with pins the out of shapeliness has a form of balance.

 

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11 hours ago, Pete Moss said:

My only experience is to align the plate to the ribs, clamp, drill through the plate into the top and bottom blocks. You can insert drill bits as pins and scribe the outline.

This is the only way  I have done it too.

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13 hours ago, duane88 said:

We put a small dot on the inner most part of the corner blocka and a small dot on the insdie corners of the end blocks. The blocks are still full and when you shape the blocks the spot where you glued will hopefully be carved away. Mike Scoggins used to bitch at me for putting too big of a dot. You do want it to pop off when you want to get it off. He used the tip of a wooden match to place the micro-dot. We left the plates spot glued to the rib structure for much of the work of the outline, purfling and working the arch down with finger planes.

p.s. pop the plates off with your opening knife. If you need a chisel, you used too much glue.

I can understand purfling the plates after assembly but why do all this other stuff while the plates are on the ribs and then have to remove and realign them?

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5 hours ago, nathan slobodkin said:

I can understand purfling the plates after assembly but why do all this other stuff while the plates are on the ribs and then have to remove and realign them?

You don't have to realign them. We used pins, but they hold the ends and when doing the outline and purfling the corners need to be secured somehow, and they chose to tack them down with a dot of white glue. Mike's method was as we were taught at school, since he was also a teacher at the school, and the inside template was derived from the outside template, then the outline was derived from the rib structure. We did use both at school, making the rib structure from the inside template and the outline from the outside template, but as a student, you didn't have a very even overhang, partly because of lack of skill at that point.

Everyone has their own method(s) that they learned or arrived at. Sometimes we change things that we learned, sometimes we stick with what we were taught.  He asked a question, I answered. That's what I do.

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I asked because I was interested, not to criticize anyone. For me  the outline and arching would both be more difficult than having the plate flat on the bench for filing and planing and I am wondering why you and a whole bunch of Germans prefer to do them on the ribs. (I didn't realize until just now that this method arched the plates while on the ribs as well as finalizing the outline.) I'm sure whatever you are used to is the easiest for you.

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Well, Peter Prier taught Mike, I went to the school, and then studied with Mike, so that is what I ended up with, for better or for worse. 

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      I  also use full length alignment pins (toothpicks  ~ 2mm) that are drilled right through the blocks and then when the back's outline is almost finished to around 3 mm overhang I temporarily attach the back with double sided tape on the blocks.  Occasionally I might add a dot of hide glue in the middle of the rib section if there is a gap.  Then the outline is finished to 2.5 to 2.7 mm overhang.   The back is removed and then purfled. Then the garland is removed,  and trimmed completely to about 55 gm on average.  The back is fully clamped and glued by removing a few at a time. 

      After the back is glued I then draw the outline for the top and follow the same method.  I used to do both top and back at the same time when I first started making but after gluing the back very often (always) there was some distortion in the rib outline (never completely perpendicular)  which makes for an uneven overhang.  I use metal alignment pins to transfer the hole location to the top afterwards...  see pictures

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