Table tops and glue

[STEVE BARRY]

Been messing around with some 3D designs for small table tops. I did them in end grain because it's just easier to work with. I'm on my third top. First one was okay and I'll probably hang it on my wall, given my lack of pictures and too many little holidays in the piece that it's not something I would sell.

Second one came out a little better, thought I had the angles nailed, but I didn't and it turned out to be a real pain in the ass. This one turned out better. Unfortunately I framed it out in jatobo, because I had some laying around. Thought I could find something to match it for the base because that stuff is heavier than lead. Not sure how it'll end up, but I'm going to keep it. Still not happy with some of the things going on with it, so no sale.

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Working on this last piece and overall very pleased. The second piece I glued up the design into a single piece about 3/8" thick. Glued down one corner of the frame onto some baltic birch. Glued up the back of the design and it sprung up like one of those square minnow nets. A real nightmare wrestling with it to get it down on the birch.

This last piece, I just glued the substrate and laid down the 3 pieces, which were six of those triangles glued up like a parallelogram. Figured they wouldn't curl quite as badly like that, but they did. So I preglued each row, three of those parallelograms with CA glue and then glued them to the birch. Easier to control two long pieces than six short ones.

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My question is this, I'm using titebond 2, but for gluing the design to the substrate would epoxy get soaked up into the grain like the titebond and cause it to curl as badly. I think I've got a reasonably good system worked out, but if I could keep the wood from bowing while I'm doing it , that would make things a lot easier

[John TenEyck]

Epoxy has no water, so it won't cause the wood to bow like TB or any other glue made with water. That said, I would not glue 3/8" thick stuff onto a stable substrate like Baltic birch plywood. Any solid wood thicker than 1/4", and even less in my mind, is going to have seasonal expansion/contraction problems when glued down to a stable substrate. I would make those parts 3/16", if possible, and I would add something equally thick on the back side of the plywood to end up with a seasonally stable piece.

John

[Richard Coers]

John is exactly right. I was taught to not glue any solid hardwood over 3/32 to a substrate. At that thickness is has the characteristic of veneer. Anything over that and it acts like hardwood. That means seasonal wood movement.

[Maurice Mcmurry]

Good advice in the previous 2 responses. I think Titebond will be fine as long as your finished product is balanced. Meaning from the center out each layer is the same or very similar regarding thickness and and wood type. So for something like your very cool 3 D design, I would glue a similar structure made of similar wood to the back of the plywood as well as the front.

[STEVE BARRY]

Good advice in the previous 2 responses. I think Titebond will be fine as long as your finished product is balanced. Meaning from the center out each layer is the same or very similar regarding thickness and and wood type. So for something like your very cool 3 D design, I would glue a similar structure made of similar wood to the back of the plywood as well as the front.

I don't have a problem with the titebond other than causing the wood to bow. I almost need three hands to glue it down. Having a flashback to some old comedy or cartoon where something keeps getting tucked in and pops out in another place. The epoxy might help in that regard

[STEVE BARRY]

Epoxy has no water, so it won't cause the wood to bow like TB or any other glue made with water. That said, I would not glue 3/8" thick stuff onto a stable substrate like Baltic birch plywood. Any solid wood thicker than 1/4", and even less in my mind, is going to have seasonal expansion/contraction problems when glued down to a stable substrate. I would make those parts 3/16", if possible, and I would add something equally thick on the back side of the plywood to end up with a seasonally stable piece.

John

Thank you. Might try the epoxy next time, might simplify that part of the build. Appreciate your thoughts on the thickness. This one started out a 5/16". One piece bowed up in the middle, I might have forgotten to tighten down one of the cauls? So right now I'm probably a little under 1/4" after rough sanding. So would 1/4 maple end grain work for the back. It's the least expensive hardwood I've got in the piece.

[John TenEyck]

Thank you. Might try the epoxy next time, might simplify that part of the build. Appreciate your thoughts on the thickness. This one started out a 5/16". One piece bowed up in the middle, I might have forgotten to tighten down one of the cauls? So right now I'm probably a little under 1/4" after rough sanding. So would 1/4 maple end grain work for the back. It's the least expensive hardwood I've got in the piece.

Yes, 1/4" maple should be fine. I'm not even sure it would need to be end grain but using it would eliminate any concerns as to grain orientation. Sand them to the same thickness, and something no more than 3/16" thickness and it likely will be stable over the long haul.

John

[Pat Germain]

Escher would approve.

[Kevin Jenness]

I agree with the comments on thickness and balancing. Epoxy will not swell the pieces but it will wick up through endgrain. You may want to parge the surface with more epoxy, and definitely wax your caul thoroughly. If the faces are pre-assembled and you are using a press and working expeditiously you should be able to use pva glue but epoxy will give more working time and a stiffer glueline, plus it is good at filling gaps if that is an issue.

Nice design by the way.

[STEVE BARRY]

I agree with the comments on thickness and balancing. Epoxy will not swell the pieces but it will wick up through endgrain. You may want to parge the surface with more epoxy, and definitely wax your caul thoroughly. If the faces are pre-assembled and you are using a press and working expeditiously you should be able to use pva glue but epoxy will give more working time and a stiffer glueline, plus it is good at filling gaps if that is an issue.

Nice design by the way.

Being how I'm a hack when it comes to woodworking, I will heed the advice given here when it comes to thickness. Might just take this one down a little more rather than mess with a backing. What I might do in the future with any of the three D stuff is cut around half inch pieces, glue up the lengths then slice them in half on the bandsaw. give me two for the price of one. Ive got some scraps I can work with to see just how thin I can go. Would the glue soak through enough that it would show up when sanded down. If it does I'll go with backing

[STEVE BARRY]

Escher would approve.

Gotta laugh, I never heard of the guy till a friend mentioned him, then my sister in law. Always liked geometric designs as a kid, but art wasn't my thing. JHS art teacher told my mom she should take me to a psychiatrist. I said to my mom did you ask her why. She told me it was because I painted my face green when I did my self portrait. I told her I didn't need a shrink, I just hated that witch. Now I find myself thinking about contrast and color palettes. Go figure

[Bob Cooper]

Steve, how are you cutting your parts to get such crisp edges?

[al ladd]

I did some similar work about 30 years ago, some of which I've kept or stayed in the family so I've been able to see how it stands the test of time. Large end grain constructions are apt to crack. Here thinness isn't really your friend. Very thick, like butcher block (3-6") will slow down or limit the seasonal movement extremes, especialiy with something like an epoxy or parafin finish. That makes large pieces prohibitively expensive to make, except commission work for rich people.The piece with the face grain frame will almost certainly push the frame open next summer, and reveal a big gap this winter. I used to make the end grain panels about 1" thick, and bevel them thinner at the periphery, and contain them within a frame that allowed for wood movement.So the frame sort of floated on the panel. Had some success with thinner panels adhered with silicone (allowing movement) to a plywood backer, again contained within a frame that allowed like 1/4" of movement for a 24" square panel . Calculate the wood movement that will occur and you might be shocked. Some laminations will crack from normal wood movement if the stresses get too large., even with no influence from a backer or frame. Scale and the extremes of ambient moisture it will be exposed to (and a moisture retention finish)are the determining factors.
I don't think the usual advice about balancing really applies here. Etsy and amateur woodworkig sites are full of end grain constructions that will almost certainly fail in most temperate environments.

[STEVE BARRY]

I did some similar work about 30 years ago, some of which I've kept or stayed in the family so I've been able to see how it stands the test of time. Large end grain constructions are apt to crack. Here thinness isn't really your friend. Very thick, like butcher block (3-6") will slow down or limit the seasonal movement extremes, especialiy with something like an epoxy or parafin finish. That makes large pieces prohibitively expensive to make, except commission work for rich people.The piece with the face grain frame will almost certainly push the frame open next summer, and reveal a big gap this winter. I used to make the end grain panels about 1" thick, and bevel them thinner at the periphery, and contain them within a frame that allowed for wood movement.So the frame sort of floated on the panel. Had some success with thinner panels adhered with silicone (allowing movement) to a plywood backer, again contained within a frame that allowed like 1/4" of movement for a 24" square panel . Calculate the wood movement that will occur and you might be shocked. Some laminations will crack from normal wood movement if the stresses get too large., even with no influence from a backer or frame. Scale and the extremes of ambient moisture it will be exposed to (and a moisture retention finish)are the determining factors.
I don't think the usual advice about balancing really applies here. Etsy and amateur woodworkig sites are full of end grain constructions that will almost certainly fail in most temperate environments.

I'm finding that out. I've been gifting some cutting boards to family and friends. Small boards maybe a foot square and three quarters thick. Couple of my cousins had boards that started splitting. The boards are pretty and most of the wives threaten their husbands with castration, so they're more decorative than anything else. I'm guessing a big reason s that to get some of the colors and contrast, I'll mix in edge grain, mostly yellow heart, sometimes walnut when it has a brindle pattern look. I've been reluctant to sell stuff, but even more so now with a few of the failures. I'm not doing this to make money, paying for a little lumber would be nice, but I'd like to give people something that will hold up. I've got some pieces laying around for awhile, but my house is pretty much a constant 74 and humidity in the mid to high fifties if I'm to believe the gauges.

[STEVE BARRY]

Steve, how are you cutting your parts to get such crisp edges?

On these tops, I plane all the boards to the same thickness and cut them to the same widths. My table saw is a saw stop. I bought some dado inserts because they're solid in the front and don't dip when you're pushing narrow pieces through. Also pieces don't hang up. I use a digital gauge for the angles, but I started cutting pieces, trapezoids and gluing them together with CA glue to check for accuracy. Digital gauge measures in tenths so I started gluing up test pieces because the final product was off and didn't work. Once I set the angles I cut the center triangles. If I start with two inch wide pieces, I cut the angles in all the ends, when I'm done I flip them, figure the fence setting and cut all of them through. Basically the same for the trapezoids around the center piece, but those are the fence side pieces I keep. I run all of them through, step one then step two. I just bought some poplar to make some test pieces. Cut them the same size as the other then trim them to fit the triangles. If I screw it up I try again till I get it right. I've been using Amana industrial blades, full kerf. Cleaner cut than the diablo blades. The solid insert helps a lot, because the one that comes with the saw dips on the narrow pieces and I think that contributes to saw marks. I made a jig for glue ups. I used maple, glued up some eight quarter, cut in the angles with the same setting. Once I have the angle set I never touch it throughout the cuts. Does that make sense? If not maybe I can dig up some pictures

I'm still experimenting with some things