All This Talk of Gluing Edges: Practical Illustration

All this talk of edge glue joints and glue starvation and clamping pressure and blah, blah, blah.... SWMBO had a request so I needed to do a quick panel glue-up. Just two 7" poplar boards edge joined for some little side table thingie that wimenfolk like. I don't know, I just make sawdust.

So anyway, I just wanted to put in the very minimum effort to show how just a table saw can do what you need. Also, to show how little glue is needed (I actually STILL used too much) and how little clamping pressure and time are needed with modern PVA glues.

The first 2 pictures shows *one* technique (I have several that use the TS) for putting a straight edge on a rough-sawn board. Once you have one straight edge-- flip and repeat and you have parallel straight edges.

3rd pic shows a thin covering of glue on each edge. Again, I still think I used to much as can be seen in the squeeze-out in the following 2 pics.

The next 2 pics show how strong a glue joint is after only a couple hours in the clamps. Spoiler alert! The wood breaks, not the glue.

The last pic shows the stained panel and how tight and imperceptible the joint is.

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Reply to
-MIKE-
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Thanks for that. I'd agree, too much glue.

Nice simple jig for creating a straight edge. Is that a Diablo blade? Which style?

I switched out my freshly sharpened 24 tooth rip blade for a freshly sharpened 40 tooth Diablo general purpose and got a much smoother rip. I'll save the 24 tooth for rough stuff.

Reply to
DerbyDad03

You know, Jerry, the inventor of the Dubby sled uses masking tape to clamp the sides of small boxes together while the glue dries. If your Slye edges are true you do not need a lot of pressure.

Reply to
Leon

*Full* kerf, Freud Glue Line Rip blade.

I'm one to make sure there's an even coat of glue across the surface of the wood to be joined. Some guys just squirt a thin line and let the glue spread out and cover when the two pieces are pushed together. Not sure that always works, but hey it's still probably enough.

When you spread out glue on an edge, it's almost impossible to *not* get too much glue in the joint. I've seen a LOT more squeeze-out in other guys' projects, including my out.

I guess my goal is to get some perceivable squeeze-out with no bubbles. If you can't get that, then next best is no dripping. With this glue-up, I got bubbles without drips.

Reply to
-MIKE-

If you don't spread the glue to completely cover the surface, the entire surface might not get covered when clamped, THAT is glue starvation. I use one of those silicone brushes that WoodCraft sells, Rockler too, to spread the bead on the surface. They clean easily and if you forget to clean the glue off you can pull it off after the glue dries.

If yo simply squirt and go you really never learn how much is enough. If you brush the bead you get really good at knowing how much to apply.

Reply to
Leon

It's all very interesting to me and always has been a topic that piques my interest. I still don't know if I've ever seen a scientific guide to clamping pressure. You'd think it's been done and is out there, but I haven't seen it.

The masking tape thing really has me curious. At some point, with masking tape, you have enough PSI on a small enough section to be as effective as a screw clamp.

I used masking tape to glue plyboo edging on this cabinet.

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Those "bandy clamps" from Rockler certainly provide enough pressure.

There comes a point with screw clamps where you have enough pressure for a properly glued joint and anything more is just compressing the wood or distorting it. I would argue that point is much sooner than most of us would believe.

I think I may do a similar "experiment" with several glue-ups using the same wood but with less and less glue and less and less clamping pressure.

Reply to
-MIKE-

I almost always use a small, soft brayer with PVA. It's quick, effective a nd rinses right off easily. You sort of get the hang of how thick a bead t o lay down for proper coverage depending on thickness and material.

JP

Reply to
JayPique

Totally agree.

I have those brushes and paddles, too, but I always end up just using my finger. I've just gotten very good and fast at swiping down an edge using my find, on the side with a little bend at the last knuckle. It acts like a plow and I can direct the flow of the glue. It also keeps the excess glue collected in a puddle in front of my finger, so any excess is picked up pretty clean at the end of the swipe.

The still use the brushes and paddles for dados and rabbets.

Reply to
-MIKE-

Good idea. I may have to try that sometime.

Reply to
-MIKE-

Yeah, I got tired of cleaning glue off of my fingers and hands some time ago.. LOL

Reply to
Leon

FWIW long glues ups usually have imperfect straight surfaces. There is some degree of bend that you may not actually see. Easier to see if you bring the long pieces together before applying glue and you see a gap anywhere along the joint. Those type glue ups need the extra pressure to squeeze the glue out. And I have never had one of those fail either. The shorter, smaller, and flatter the surface the less pressure you need to bring the surfaces together.

Reply to
Leon

HANDS!? Now, I *know* you're using too much glue. :-p Half a paper towel does it me.

Reply to
-MIKE-

That is very true. Another thing to consider and a big reason it always seems to require more clamping pressure for longer panels. Good point.

Reply to
-MIKE-

Hell, if I had a paper towels handy it would be stuck to me somewhere and likely look like a piece of toilet paper stuck to my back side. ;~)

Reply to
Leon

You forgot to mention the oxidized edge vs. the fresh edge; spring joints vs. flat; jointer edge vs. sawn edge vs. hand-planed edge vs. sanded edge; hide glue vs. poly... you get the idea! LOL

Reply to
John Grossbohlin

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