Proper glueing techniques for joints

[Burkhardt]

Maybe I am showing my non-professionalism here...but I am more of a technologist than a skilled wood worker. Although I have done many wood projects since I was a kid (my dad was a high school shop class teacher) and got some pretty projects, I believe none of them qualifies as "fine woodworking" artistry.

Anyway, as you may have seen in other posts I have been interested in the CNC aspects of joinery, like my dovetail software or tricky box joint software I am working on lately. One thing that bothers me is that I still don't have a satisfactory technique for actually glueing such joints.

Here is the problem: I can get very strong joints with ample application of the common Titebond 1/2/3 glues. I really don't like Titebond 3 because of the dark brown appearance. Titebond 1 and 2 are kind of O.K. Lately I have been using more the Canadian Weldbond brand white glue because it is really strong and dries up to an almost glass clear. It is thick and does not run but it is hard to sand and smears due to the rubbery consistency. All of these glues are difficult to clean. If wiped off with water they may still seal the surface and leave blemishes when finishing. I find it almost impossible to avoid glue squeeze-out when pushing the parts together.

So, is there some good advice how to do this better? Something else like hide glue maybe easier to deal with?

Thanks for any advice!

[Simops]

One technique is to dry fit and use blue painters tape around the joint edges....separate and then glue. After glue dries remove tape.
Laborious in a way but effective.

Another method is to use less glue strategically placed to reduce squeeze out.....over glueing doesn't necessarily mean stronger glue joint.

Another glue...polyurethanes....tend foam out of joint but when dry are easily removed with sharp chisel leaving little if any residue on adjoining surface....as long as you let it bubble out and not disturb it until hard dry....

Cheers

[catbourger]

Still another technique is to paste wax the joint around (but of course not on) the gluing area where the glue is likely to appear. After the joint has dried, the wax will come right off with mineral spirits or paint thinner. Be careful not to use paste wax that contains silicones, however.
There was an article several issues ago about this in Fine Woodworking.

Karl

[dlcw]

I use a glue called Woodweld (two-part plastic resin glue) for complex glue ups. It has an open working time of around 45 to 50 minutes and is MUCH stronger then any of the yellow, brown or white glues. You have to be very careful when using tools on it when dry as it is hard as glass and will tear up planer and jointer knives.

On fine furniture, I use Gorilla White wood glue. Dries clear and is strong. For cabinetry I use yellow glue that is more moisture resistant.

As Scott said, spot glue in strategic places to minimize squeeze out. When I glue the edges of two boards together I have a squeeze out bead of no more then 1mm. After about 30 minutes I use a carbide tipped scrapper to remove the tiny beads. They just pop right off. I am a minimalist when it comes to gluing. Over the years I've learned how much glue to apply to make sure the joint is not glue starved but still has enough to be strong. You don't need glue dripping all over the place to ensure a good joint. That 1mm bead I talked about earlier indicates that both surfaces of both of the boards is completely coated with glue, otherwise if I don't get that tiny bead, I know I've staved the joint.

The one joint I break my rule on is 5-piece doors. I want to have more squeeze out to ensure I have really good coverage on the joints as these are all there is to hold the door together. But, I let it dry for about 45 minutes and remove the squeeze out. This way I don't get the smearing of glue, but also don't need to take a jackhammer to it to get the hardened glue off.

Another thing to make sure of is that there is enough "slop" in the joint to ensure there is room for the glue. For a loose joint you will need epoxy with fillers. For super tight joints, the joint will be glue staved creating a week joint. I normally use about a .007" slop on the CNC when creating joints. For non CNC joinery, I like a loose friction fit.


Just takes time and experience to figure out how much glue is "enough but not too much".

[jTr]

To address the specific glue up you are referring to:
- When you dry-fit the dovetailed drawers, leave them together.
- If there are any irregularities- slightly proud pins or tails, go ahead and sand them as if the box were glued. If need be, use a few clamps to hold firm.
- Head to the finish room with the boxes dry assembled and apply your finish. This is best if spraying, as the finish is not as likely to seep into joints as may be the case with a heavily applied oil coat - just be careful around joints if you're doing this.

Once finishing is complete, dis-assemble and glue up. Glue will squeeze out, but can be wiped off with a damp cloth. You may also wait until it is partially cured (less smearing) or even fully cured - glue should pop right off. If you have a trouble-spot, such as a joint that did not level completely during glue up, you can simply scuff and re-finish that side of the drawer box.

Honestly, my last batch of dovetailed drawers was simply glued up, glue squeeze was sanded off as joints were finessed with sanding, then finished - they turned out great. Bear in mind, I do this for a living, so I must deliver prime quality in the most efficient manner - these are simply half-blind dovetails cut on the 'bot using Gary C's dovetail system.

I very much admire the joinery methodology you've come up with - perhaps one of these strategies will be useful in producing a finish that is consummate for that level of craft and artistry.

jeff

[Burkhardt]

Thanks all for the advice! There are some good tricks I will try.

The problem with box joints and dovetails is obviously the convoluted surface that does not lend itself to even and sparing glue application like a dado slot.

I guess I just need to practice patience when applying and not go with the more/merrier approach. I any case, the pre-finish , waxing or taping should help, especially on the inside

[Brian Harnett]

Epoxy is an option once cured it is easy to sand without gumming up.